Total Motion Release Seminars
Where Miracles Happen Everyday

You can thank Bill Jones, PT for this extensive amount of research. He was incredibly skeptical during his first TMR workshop and went home and pulled any article he could find that related to the subject matter. The earliest research he could find was from the 1890s. All this material helped him better wrap his mind around the underlying concept of TMR.

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At-home resistance tubing strength training increases shoulder
strength in the trained and untrained limb

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Here is a editorial JOSPT on Regional Interdependence from

www.jospt.org/members/getfile.asp?id=2959 (it will automatically download)

ROBERT S. WAINNER, PT, PhD, ECS, OCS, FAAOMPT1
JULIE M. WHITMAN, PT, DSc, OCS, FAAOMPT2
JOSHUA A. CLELAND, PT, DPT, PhD, OCS, FAAOMPT3
TIMOTHY W. FLYNN, PT, PhD, ECS, OCS, FAAOMPT4
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Br J Sports Med. 2012 Nov 28. [Epub ahead of print]

Unilateral surgical treatment for patients with midportion Achilles tendinopathy may result in bilateral recovery.

Alfredson H, Spang C, Forsgren S.

Source

Department of Surgical and Perioperative Sciences, Sports Medicine, Umeå University, Umeå, Sweden.

Abstract

BACKGROUND:

Bilateral midportion Achilles tendinopathy/tendinosis is not unusual, and treatment of both sides is often carried out. Experiments in animals suggest of the potential involvement of central neuronal mechanisms in Achilles tendinosis.

OBJECTIVES:

To evaluate the outcome of surgery for Achilles tendinopathy.

METHODS:

This observational study included 13 patients (7 men and 6 women, mean age 53 years) with a long duration (6-120 months) of chronic painful bilateral midportion Achilles tendinopathy. The most painful side at the time for investigation was selected to be operated on first. Treatment was ultrasound-guided and Doppler-guided scraping procedure outside the ventral part of the tendon under local anaesthetic. The patients started walking on the first day after surgery. Follow-ups were conducted and the primary outcome was pain by visual analogue scale. In an additional part of the study, specimens from Achilles and plantaris tendons in three patients with bilateral Achilles tendinosis were examined.

RESULTS:

Short-term follow-ups showed postoperative improvement on the non-operated side as well as the operated side in 11 of 13 patients. Final follow-up after 37 (mean) months showed significant pain relief and patient satisfaction on both sides for these 11 patients. In 2 of 13 patients operation on the other, initially non-operated side, was instituted due to persisting pain. Morphologically, it was found that there were similar morphological effects, and immunohistochemical patterns of enzyme involved in signal substance production, bilaterally.

CONCLUSION:

Unilateral treatment with a scraping operation can have benefits contralaterally; the clinical implication is that unilateral surgery may be a logical first treatment in cases of bilateral Achilles tendinopathy.

Phantom limb pain: relief by application of TENS to contralateral extremity.

Carabelli RA, Kellerman WC. Arch Phys Med Rehabil. 1985 Jul;66(7):466-7.

Abstract

Three adult patients with below-knee amputation of various etiologies were treated at Norristown's Sacred Heart Hospital and Rehabilitation Center in the fall of 1983. The patients ranged in age from 48 to 64 years and two were men.

All three had complaints of phantom limb pain originating from various anatomic sites of the amputated extremity. In all three cases the phantom limb pain was severe and hampered prosthetic training.

The patients were treated solely by application of the TENS unit to the contralateral extremity at the sites where the phantom pain originated on the amputated limb.

All three patients responded to treatment and were able to continue their prosthetic training. A six-month follow-up showed no pain recurrence of phantom limb pain in all three cases.

Contralateral reflexes

Etymology: L, contra, against, latus, side, reflectere, to bend back

an overflow phenomenon of the nervous system in which a reflex is elicited on one side of the body by a stimulus to the opposite side.

Contralateral reflex arcs involve sensory receptors and neurons on one side of the body and motor neurons and effectors on the opposite side.

Allen, Connie, and Valerie Harper. Anatomy and Physiology Binder Ready Version. 3rd ed. Danvers: John Wiley & Sons, 2008.

"Under normal conditions, the pupils of both eyes respond identically to a light stimulus, regardless of which eye is being stimulated. Light entering one eye produces a constriction of the pupil of that eye, the direct response, as well as a constriction of the pupil of the unstimulated eye, the consensual response."

http://en.wikipedia.org/wiki/Pupillary_light_reflex

Cross education and immobilisation: Mechanisms and implications for injury rehabilitation. J Sci Med Sport. 2012 Mar;15(2):94-101.Epub 2011 Sep 15. Hendy AM, Spittle M, Kidgell DJ.

Abstract

OBJECTIVES:

Unilateral strength training produces an increase in strength of the contralateral homologous muscle group. This process of strength transfer, known as cross education, is generally attributed to neural adaptations. It has been suggested that unilateral strength training of the free limb may assist in maintaining the functional capacity of an immobilised limb via cross education of strength, potentially enhancing recovery outcomes following injury. Therefore, the purpose of this review is to examine the impact of immobilisation, the mechanisms that may contribute to cross education, and possible implications for the application of unilateral training to maintain strength during immobilisation.

RESULTS:

Immobilisation is well known for its detrimental effects on muscular function. Early reductions in strength outweigh atrophy, suggesting a neural contribution to strength loss, however direct evidence for the role of the central nervous system in this process is limited. Similarly, the precise neural mechanisms responsible for cross education strength transfer remain somewhat unknown. Two recent studies demonstrated that unilateral training of the free limb successfully maintained strength in the contralateral immobilised limb, although the role of the nervous system in this process was not quantified.

CONCLUSIONS:

Cross education provides a unique opportunity for enhancing rehabilitation following injury.By gaining an understanding of the neural adaptations occurring during immobilisation and cross education, future research can utilise the application of unilateral training in clinical musculoskeletal injury rehabilitation.

Cross-education of muscle strength: cross-training effects are not confined to untrained contralateral homologous muscle.Scand J Med Sci Sports. 2011 Dec;21(6):e359-64. doi: 10.1111/j.1600-0838.2011.01311.x. Epub 2011 Apr 18.

Sariyildiz M, Karacan I, Rezvani A, Ergin O, Cidem M.

Abstract

The aim of this study was to evaluate whether electrical muscle stimulation (EMS) on dominant wrist flexors causes an increase in the muscle strength of the contralateral wrist extensors. Twenty-three healthy, young, adult men were included in this prospective, double-blind, controlled study. Participants were randomly allocated to the EMS group or Control group. Electrodes were placed over the flexor aspect of the right forearm in both groups. In the EMS group, passive wrist extension and (EMS) that caused powerful muscle contraction were simultaneously applied. In the Control group, a conventional mode of transcutaneous electrical nerve stimulation was applied without causing any contraction. A group effect (P=0.0001) and group-by-time interaction were found (P=0.0001) for both the wrist flexor and extensor muscles, but not group-by-time-by-arm interactions. This implies that the effect of the interventions was similar in both arms, but that the response was significantly larger in the EMS than in the Control group. The results of the current study suggest that cross-education is not confined to the untrained contralateral wrist flexors and that the strength increase may also be observed in the contralateral wrist extensors.

Neuro-physiological adaptations associated with cross-education of strength.

Farthing JP, Borowsky R, Chilibeck PD, Binsted G, Sarty GE.

Brain Topogr. 2007 Winter;20(2):77-88. Epub 2007 Oct 12.

Abstract

Cross-education of strength is the increase in strength of the untrained contralateral limb after unilateral training of the opposite homologous limb. We investigated central and peripheral neural adaptations associated with cross-education of strength. Twenty-three right-handed females were randomized into a unilateral training group or an imagery group. A sub-sample of eight subjects (four training, four imagery) was assessed with functional magnetic resonance imaging (fMRI) for patterns of cortical activation during exercise. Strength training was 6 weeks of maximal isometric ulnar deviation of the right arm, four times per week. Peak torque, muscle thickness (ultrasound), agonist-antagonist electromyography (EMG), and fMRI were assessed before and after training. Strength training was highly effective for increasing strength in trained (45.3%; P < 0.01) and untrained (47.1%; P < 0.01) limbs. The imagery group showed no increase in strength for either arm. Muscle thickness increased only in the trained arm of the training group (8.4%; P < 0.001). After training, there was an enlarged region of activation in contralateral sensorimotor cortex and left temporal lobe during muscle contractions with the untrained left arm (P < 0.001). Training was associated with a significantly greater change in agonist muscle EMG pooled over both limbs, compared to the imagery group (P < 0.05). These results suggest that cross-education of strength may be partly controlled by adaptations within sensorimotor cortex, consistent with previous studies of motor learning. However, this research demonstrates the involvement of temporal lobe regions that subserve semantic memory for movement, which has not been previously studied in this context. We argue that temporal lobe regions might play a significant role in the cross-education of strength.

Strength gains by motor imagery with different ratios of physical to mental practice. Reiser M, Büsch D, Munzert J. Front Psychol. 2011;2:194. Epub 2011 Aug 19.

The purpose of this training study was to determine the magnitude of strength gains following a high-intensity resistance training (i.e., improvement of neuromuscular coordination) that can be achieved by imagery of the respective muscle contraction imagined maximal isometric contraction (IMC training). Prior to the experimental intervention, subjects completed a 4-week standardized strength training program. 3 groups with different combinations of real maximum voluntary contraction (MVC) and mental (IMC) strength training (M75, M50, M25; numbers indicate percentages of mental trials) were compared to a MVC-only training group (M0) and a control condition without strength training (CO). Training sessions (altogether 12) consisted of four sets of two maximal 5-s isometric contractions with 10 s rest between sets of either MVC or IMC training. Task-specific effects of IMC training were tested in four strength exercises commonly used in practical settings (bench pressing, leg pressing, triceps extension, and calf raising). Maximum isometric voluntary contraction force (MVC) was measured before and after the experimental training intervention and again 1 week after cessation of the program. IMC groups (M25, M50, M75) showed slightly smaller increases in MVC (3.0% to 4.2%) than M0 (5.1%), but significantly stronger improvements than CO (-0.2%). Compared to further strength gains in M0 after 1 week (9.4% altogether), IMC groups showed no "delayed" improvement, but the attained training effects remained stable. It is concluded that high-intensity strength training sessions can be partly replaced by IMC training sessions without any considerable reduction of strength gains.

Benefits of motor imagery training on muscle strength.

Lebon F, Collet C, Guillot A. J Strength Cond Res. 2010 Jun;24(6):1680-7.

Abstract

It is well established that motor imagery (MI) improves motor performance and motor learning efficiently.Previous studies provided evidence that muscle strength may benefit from MI training, mainly when movements are under the control of large cortical areas in the primary motor cortex. The purpose of this experiment is to assess whether MI might improve upper and lower limbs' strength through an ecological approach and validation, with complex and multijoint exercises. Nine participants were included in the MI group and 10 in the control (CTRL) group. The 2 groups performed identical bench press and leg press exercises. The MI group was instructed to visualize and feel the correspondent contractions during the rest period, whereas the CTRL group carried out a neutral task. The maximal voluntary contraction (MVC) and the maximal number of repetitions (MR) using 80% of the pre-test MVC weight were measured. Although both MI and CTRL groups enhanced their strength through the training sessions, the leg press MVC was significantly higher in the MI group than in the CTRL group (p<0.05). The interaction between the leg press MR and the group was marginally significant (p=0.076). However, we did not find any difference between the MI and CTRL groups, both in the bench press MVC and MR. MI-related training may contribute to the improvement of lower limbs performance by enhancing the technical execution of the movement, and the individual intrinsic motivation. From an applied and practical perspective, we state that athletes may perform imagined muscles contractions, most especially during the rest periods of their physical training, to contribute to the enhancement of concentric strength.

The ipsilateral motor cortex contributes to cross-limb transfer of performance gains after ballistic motor practice. Lee M, Hinder MR, Gandevia SC, Carroll TJ. J Physiol. 2010 Jan 1;588(Pt 1):201-12. Epub 2009 Nov 16

Abstract

Although it has long been known that practicing a motor task with one limb can improve performance with the limb opposite, the mechanisms remain poorly understood.Here we tested the hypothesis that improved performance with the untrained limb on a fastest possible (i.e. ballistic) movement task depends partly on cortical circuits located ipsilateral to the trained limb. The idea that crossed effects, which are important for the learning process, might occur in the 'untrained' hemisphere following ballistic training is based on the observation that tasks requiring strong descending drive generate extensive bilateral cortical activity. Twenty-one volunteers practiced a ballistic index finger abduction task with their right hand, and corticospinal excitability was assessed in two hand muscles (first dorsal interosseus, FDI; adductor digiti minimi, ADM). Eight control subjects did not train. After training, repetitive transcranial magnetic stimulation (rTMS; 15 min at 1 Hz) was applied to the left (trained) or right (untrained) motor cortex to induce a 'virtual lesion'. A third training group received sham rTMS, and control subjects received rTMS to the right motor cortex. Performance and corticospinal excitability (for FDI) increased in both hands for training but not control subjects. rTMS of the left, trained motor cortex specifically reduced training-induced gains in motor performance for the right, trained hand, and rTMS of the right, untrained motor cortex specifically reduced performance gains for the left, untrained hand. Thus, cortical processes within the untrained hemisphere, ipsilateral to the trained hand, contribute to early retention of ballistic performance gains for the untrained limb.

Effects of cross-education on the muscle after a period of unilateral limb immobilization using a shoulder sling and swathe. Magnus CR, Barss TS, Lanovaz JL, Farthing JP.

J Appl Physiol. 2010 Dec;109(6):1887-94. Epub 2010 Oct 21.

Abstract

The purpose of this study was to apply cross-education during 4 wk of unilateral limb immobilization using a shoulder sling and swathe to investigate the effects on muscle strength, muscle size, and muscle activation.Twenty-five right-handed participants were assigned to one of three groups as follows: the Immob + Train group wore a sling and swathe and strength trained (n = 8), the Immob group wore a sling and swathe and did not strength train (n = 8), and the Control group received no treatment (n = 9). Immobilization was applied to the nondominant (left) arm. Strength training consisted of maximal isometric elbow flexion and extension of the dominant (right) arm 3 days/wk. Torque (dynamometer), muscle thickness (ultrasound), maximal voluntary activation (interpolated twitch), and electromyography (EMG) were measured. The change in right biceps and triceps brachii muscle thickness [7.0 ± 1.9 and 7.1 ± 2.2% (SE), respectively] was greater for Immob + Train than Immob (0.4 ± 1.2 and -1.9 ± 1.7%) and Control (0.8 ± 0.5 and 0.0 ± 1.1%, P < 0.05). Left biceps and triceps brachii muscle thickness for Immob + Train (2.2 ± 0.7 and 3.4 ± 2.1%, respectively) was significantly different from Immob (-2.8 ± 1.1 and -5.2 ± 2.7%, respectively, P < 0.05). Right elbow flexion strength for Immob + Train (18.9 ± 5.5%) was significantly different from Immob (-1.6 ± 4.0%, P < 0.05). Right and left elbow extension strength for Immob + Train (68.1 ± 25.9 and 32.2 ± 9.0%, respectively) was significantly different from the respective limb of Immob (1.3 ± 7.7 and -6.1 ± 7.8%) and Control (4.7 ± 4.7 and -0.2 ± 4.5%, P < 0.05). Immobilization in a sling and swathe decreased strength and muscle size but had no effect on maximal voluntary activation or EMG. The cross-education effect on the immobilized limb was greater after elbow extension training. This study suggests that strength training the nonimmobilized limb benefits the immobilized limb for muscle size and strength.

Corticospinal adaptations and strength maintenance in the immobilized arm following 3 weeks unilateral strength training.Pearce AJ, Hendy A, Bowen WA, Kidgell DJ. Scand J Med Sci Sports. 2012 Mar 19. doi: 10.1111/j.1600-0838.2012.01453.x. [Epub ahead of print]

Abstract

Cross-education strength training has being shown to retain strength and muscle thickness in the immobilized contralateral limb. Corticospinal mechanisms have been proposed to underpin this phenomenon; however, no transcranial magnetic stimulation (TMS) data has yet been presented. This study used TMS to measure corticospinal responses following 3 weeks of unilateral arm training on the contralateral, immobilize arm. Participants (n = 28) were randomly divided into either immobilized strength training (Immob + train) immobilized no training (Immob) or control. Participants in the immobilized groups had their nondominant arm rested in a sling, 15 h/day for 3 weeks. The Immob + train group completed unilateral arm curl strength training, while the Immob and control groups did not undertake training. All participants were tested for corticospinal excitability, strength, and muscle thickness of both arms. Immobilization resulted in a group x time significant reduction in strength, muscle thickness and corticospinal excitability for the untrained limb of the Immob group.Conversely, no significant change in strength, muscle thickness, or corticospinal excitability occurred in the untrained limb of the Immob + train group. These results provide the first evidence of corticospinal mechanisms, assessed by TMS, underpinning the use of unilateral strength training to retain strength and muscle thickness following immobilization of the contralateral limb.

Changes in functional magnetic resonance imaging cortical activation with cross education to an immobilized limb. Farthing JP, Krentz JR, Magnus CR, Barss TS, Lanovaz JL, Cummine J, Esopenko C, Sarty GE, Borowsky R. Med Sci Sports Exerc. 2011 Aug;43(8):1394-405.

Abstract

PURPOSE:

The purpose of this study was to assess cortical activation associated with the cross-education effect to an immobilized limb, using functional magnetic resonance imaging.

METHODS:

Fourteen right-handed participants were assigned to two groups. One group (n = 7) wore a cast and strength trained the free arm (CAST-TRAIN). The second group (n = 7) wore a cast and did not strength train (CAST). Casts were applied to the nondominant (left) wrist and hand. Strength training was maximal isometric handgrip contractions (right hand) 5 d·wk(-1). Peak force (handgrip dynamometer), muscle thickness (ultrasound), EMG, and cortical activation (functional magnetic resonance imaging) were assessed before and after the intervention.

RESULTS:

CAST-TRAIN improved right handgrip strength by 10.7% (P < 0.01) with no change in muscle thickness. There was a significant group × time interaction for strength of the immobilized arm (P < 0.05). Handgrip strength of the immobilized arm of CAST-TRAIN was maintained, whereas the immobilized arm of CAST significantly decreased by 11% (P < 0.05). Muscle thickness of the immobilized arm decreased by an average of 3.3% (P < 0.05) for all participants and was not different between groups after adjusting for baseline differences. There was a significant group × time interaction for EMG activation (P < 0.05), where CAST-TRAIN showed an increasing trend and CAST showed a decreasing trend, pooled across arms. For the immobilized arm of CAST-TRAIN, there was a significant increase in contralateral motor cortex activation after training (P < 0.05). For the immobilized arm of CAST, there was no change in motor cortex activation.

CONCLUSIONS:

Handgrip strength training of the free limb attenuated strength loss during unilateral immobilization. The maintenance of strength in the immobilized limb via the cross-education effect may be associated with increased motor cortex activation.

The effect of contralateral training: Influence of unilateral isokinetic exercise on one-legged standing balance of the contralateral lower extremity in adults.Gait Posture. 2011 May;34(1):103-6. Epub 2011 May 4. Kim K, Cha YJ, Fell DW.

Abstract

PURPOSE:

To investigate the effects of unilateral isokinetic exercises on the one-legged standing balance of the contralateral lower extremity.

SUBJECTS:

A volunteer sample of 32 healthy adults (12 men and 20 women) was randomized to training and control groups.

METHODS:

The training group received unilateral hip isokinetic exercises of the dominant leg for two weeks. Contralateral single-limb balance was measured before and after intervention, including three stability index scores of balance using Biodex Stability System: Anterior-Posterior Stability Index (APSI), Medio-lateral Stability Index (MLSI), and Overall Stability Index (OSI) scores.

RESULTS:

Comparison of pre-test and post-test data revealed significant improvements in APSI, MLSI, and OSI scores in the training group (p<0.05), but not in the control group. The gains of stability scores from pre- to post-test, were also significantly greater (p<0.05) in the training group than the control group.

CONCLUSION:

These results suggest that contralateral training with unilateral isokinetic exercises increases the one-legged standing balance of the contralateral limb following a short duration of training.

Unilateral strength training increases voluntary activation of the opposite untrained limb.

Lee M, Gandevia SC, Carroll TJ. Clin Neurophysiol. 2009 Apr;120(4):802-8. Epub 2009 Feb 18

Abstract

OBJECTIVE:

We investigated whether an increase in neural drive from the motor cortex contributes to the cross-limb transfer of strength that can occur after unilateral strength training.

METHODS:

Twitch interpolation was performed with transcranial magnetic stimulation to assess changes in strength and cortical voluntary activation in the untrained left wrist, before and after 4 weeks of unilateral strength-training involving maximal voluntary isometric wrist extension contractions (MVCs) for the right wrist (n=10, control group=10).

RESULTS:

Wrist extension MVC force increased in both the trained (31.5+/-18%, mean+/-SD, p<0.001) and untrained wrist (8.2+/-9.7%, p=0.02), whereas wrist abduction MVC did not change significantly. The amplitude of the superimposed twitches evoked during extension MVCs decreased by 35% (+/-20%, p<0.01), which contributed to a significant increase in voluntary activation (2.9+/-3.5%, p<0.01). Electromyographic responses to cortical and peripheral stimulation were unchanged by training. There were no significant changes for the control group which did not train.

CONCLUSION:

Unilateral strength training increased the capacity of the motor cortex to drive the homologous untrained muscles.

SIGNIFICANCE:

The data show for the first time that an increase in cortical drive contributes to the contralateral strength training effect.

Tenocyte hypercellularity and vascular proliferation in a rabbit model of tendinopathy: contralateral effects suggest the involvement of central neuronal mechanisms

Br J Sports Med 2011;45:399-406 doi:10.1136/bjsm.2009.068122

Gustav Andersson, Sture Forsgren, Alexander Scott, James Edmund, Gaida, Johanna Elgestad Stjernfeldt, Ronny Lorentzon, Håkan Alfredson, Clas Backman, Patrik Danielson

Abstract

Objective:

To determine whether there are objective findings of tendinosis in a rabbit tendinopathy model on exercised and contralateral (non-exercised) Achilles tendons.

Design:

Four groups of six New Zealand white rabbits per group were used. The animals of one (control) group were not subjected to exercise/stimulation.

Interventions:

Animals were subjected to a protocol of electrical stimulation and passive flexion–extension of the right triceps surae muscle every second day for 1, 3 or 6 weeks.

Main Outcome Measures:

Tenocyte number and vascular density were calculated. Morphological evaluations were also performed as well as in-situ hybridisation for vascular endothelial growth factor (VEGF) messenger RNA.

Results:

There was a significant increase in the tenocyte number after 3 and 6 weeks of exercise, but not after 1 week, in comparison with the control group. This was seen in the Achilles tendons of both legs in experimental animals, including the unexercised limb. The pattern of vascularity showed an increase in the number of tendon blood vessels in rabbits that had exercised for 3 weeks or more, compared with those who had exercised for 1 week or not at all. VEGF-mRNA was detected in the investigated tissue, with the reactions being more clearly detected in the tendon tissue with tendinosis-like changes (6-week rabbits) than in the normal tendon tissue (control rabbits).

Conclusions:

There were bilateral tendinosis-like changes in the Achilles tendons of rabbits in the current model after 3 weeks of training, suggesting that central neuronal mechanisms may be involved and that the contralateral side is not appropriate as a control.

Training with unilateral resistance exercise increases contralateral strength

Joanne Munn, Robert D. Herbert, Mark J. Hancock, and Simon C. Gandevia

Journal of Applied Physiology November 2005 vol. 99 no. 5 1880-1884

Evidence that unilateral training increases contralateral strength is inconsistent, possibly because existing studies have design limitations such as lack of control groups, lack of randomization, and insufficient statistical power. This study sought to determine whether unilateral resistance training increases contralateral strength. Subjects (n = 115) were randomly assigned to a control group or one of the following four training groups that performed supervised elbow flexion contractions: 1) one set at high speed, 2) one set at low speed, 3) three sets at high speed, or 4) three sets at low speed. Training was 3 times/wk for 6 wk with a six- to eight-repetition maximum load. Control subjects attended sessions but did not exercise. Elbow flexor strength was measured with a one-repetition maximum arm curl before and after training. Training with one set at slow speed did not produce an increase in contralateral strength (mean effect of –1% or –0.07 kg; 95% confidence interval: –0.42–0.28 kg; P = 0.68). However, three sets increased strength of the untrained arm by a mean of 7% of initial strength (additional mean effect of 0.41 kg; 95% confidence interval: 0.06–0.75 kg; P = 0.022). There was a tendency for training with fast contractions to produce a greater increase in contralateral strength than slow training (additional mean effect of 5% or 0.31 kg; 95% confidence interval: –0.03–0.66 kg; P = 0.08), but there was no interaction between the number of sets and training speed. We conclude that three sets of unilateral resistance exercise produce small contralateral increases in strength.

Electromyography Results of Exercise Overflow in Hemiplegic Patients

Virginia M Mills and Lee Quintana Physical Therapy July 1985 vol. 65 no. 7 1041-1045

Abstract

The purpose of this study was to determine the effects of exercise overflow in hemiplegic patients.Eleven subjects with a diagnosis of cerebrovascular accident (CVA) performed active exercises with their uninvolved extremities while their involved extremities were monitored with EMG. The muscles monitored were the biceps brachii, triceps brachii, and quadriceps femoris. Active exercise of the comparable uninvolved muscles was performed under three different weight lifting conditions: 1) maximal weight, 2) 50% of the maximal weight, and 3) no weight. Significant (p < .05) overflow to the involved nonexercised extremities was found in all of the exercise conditions. Overflow was frequently found in all three muscle groups when only one muscle group was being exercised. Overflow always occurred in the contralateral homologous muscle. Exercise overflow appears to be an effective therapeutic technique to facilitate muscle activity in paretic muscles. This muscle activity may cause desired or undesired muscular effects during therapy in the rehabilitation of patients with CVAs.

Cross-Education After One Session of Unilateral Surface Electrical Stimulation of the Rectus Femoris, Toca-Herrera, José L; Gallach, José E; Gómis, Manuel; González, Luis M, Journal of Strength & Conditioning Research:

March 2008 - Volume 22 - Issue 2 - pp 614-618

Abstract

Thirty-six adult men were randomly assigned to a remote stimulation group (RS; n = 18) or control group (CTL; n = 18). The RS group unilaterally performed a 10-minute surface electrical stimulation program (frequency 100 Hz, impulse 300 μs, 10 seconds on/10 seconds off) on the rectus femoris of the non-dominant leg. The subjects of the CTL group relaxed for 10 minutes without performing any training. Immediately before and after the surface electrical stimulation program, the isometric strength and the electromyographic (EMG) and mechanomyographic (MMG) response of the dominant leg was measured for all subjects. The dominant leg of the RS group showed a significant increase in the isometric force (5.11%; P < 0.001) and EMG activity of the agonist muscle (4.67%; P < 0.05), whereas a decrease in EMG activity of the antagonist muscles was observed (-10.27%; P < 0.05). The MMG activity did not show any alteration. No significant changes were observed for the CTL group. These results indicate that one unilateral surface electrical stimulation session on the rectus femoris improves the efficiency of the inactive leg. At a practical level, the results open a new way to rehabilitate muscle-skeletal injuries, especially weak members that cannot do any physical work. In this case, the muscle strength (and physical efficiency) can be improved by passive electrostimulation training on the healthy member.

Effects of unilateral electromyostimulation superimposed on voluntary training on strength and cross-sectional area, Pedro Bezerra MSc, Shi Zhou PhD, Zachary Crowley BSc, Lyndon Brooks PhD, Andrew Hooper MD; Muscle & Nerve Volume 40, Issue 3, pages 430–437, September 2009

Abstract

In this study we investigate the effects of unilateral voluntary contraction (VC) and electromyostimulation superimposed on VC (EV) training on maximal voluntary (MVC) force and cross-sectional area (CSA), as assessed by magnetic resonance imaging of knee extensors. Thirty young men were randomly assigned to either a control group (CG), VC group (VG), or EV group (EVG). The VG and EVG trained the right leg isometrically three sessions per week for 6 weeks. After training, MVC increased in the right leg in the VG and in both legs in the EVG, and EVG was significantly different from CG (all P < 0.01). Increased CSA was found only in the right leg in the VG and EVG (P < 0.01), and correlated with improvements of MVC (r = 0.49, P = 0.01). It appeared that the EV training was equally effective as VC at increasing MVC and CSA, while having a greater cross-education effect. Increased strength without muscle hypertrophy in the unexercised leg of the EVG indicated that neural adaptation was responsible for the cross-education effect. Muscle Nerve 40: 430–437, 2009

Scroll about 3/4ths down the page for this one.

http://www.neurodynamicsolutions.com/solutions-clinical.php#solutionscontralateraltests

This is an excellent article in Men's Health (no it is not a research article) but really hits some very big concepts that are similar to TMR's. Kind of gives you a good overview of what is happening in the body.

Click Here to read article and Here to Read Another Related Article from Anatomy Trains

If you want to view a research article that does not have a link to it, Google the Title of the Research Article and you should find a link at least to the abstract.

This is from Ed Stiles Website. This IS the what TMR is all about. See Tensegrity Below

What does "Tensegrity" mean?

Tensegrity (or tensional integrity) is an architectural term describing how tension and compression can be balanced and distributed throughout a structure. Load or stress one portion of the structure and the whole structure will give a little to accommodate. Viewing the human body as a tensegrity structure rather than as a compressive structure such as a stack of bricks (or bones) helps to explain why an injury in one region can cause pain elsewhere. Tensegrities allow for flexibility and a resilience to the dynamic stress our bodies deal with throughout the day to run or twist or pull or even walk. But that amazing ability to instantaneously distribute forces throughout the structure also means components can be strained (or injured) far from the site where the force (or problem) originated. For treatment of pain, this makes assessing the whole body, rather than just the painful region, pivotal for treatment to work.

For more information as to tensegrity’s application to the musculoskeletal system see Ed Stiles D.O. [http://www.omtsos.com/] or

Stephen Levin M.D. [http://www.biotensegrity.com/]

For its ramifications at a cellular and disease level, see the work of Harvard professor Donald Ingber M.D. PhD [http://www.childrenshospital.org/research/ingber/].

McClatchie L,Mobilizations of the asymptomatic cervical spine can reduce signs of shoulder dysfunction in adults Manual Therapy 14(4); August 2009; 369-374. Review article at: http://www.musculoskeletalanatomy.org/Papers/McClatchie_2008.pdf

Unilateral practice of a ballistic movement causes bilateral increases in performance and corticospinal excitability J Appl Physiol 104: 1656–1664, 2008.

Review article at: http://jap.physiology.org/cgi/reprint/104/6/1656

Additional References from the above article

M, Byblow WD. Excitability changes in human forearm corticospinal projections and spinal reflex pathways during rhythmic voluntary movement of the opposite limb. J Physiol 560: 929–940, 2004.

Duque J, Mazzocchio R, Stefan K, Hummel F, Olivier E, Cohen LG. Memory formation in the motor cortex ipsilateral to a training hand. CerebCortex: Oct 10, 2007.

Zijdewind I, Butler JE, Gandevia SC, Taylor JL. The origin of activity in the biceps brachii muscle during voluntary contractions of the contralateral elbow flexor muscles. Exp Brain Res 175: 526–535, 2006.

Stefan K, Cohen LG, Duque J, Mazzocchio R, Celnik P, Sawaki L, Ungerleider L, Classen J. Formation of a motor memory by actionobservation. J Neurosci 25: 9339–9346, 2005.

Interesting Video similar to this information at:

http://www.pbs.org/wgbh/nova/sciencenow/3204/01.html

AL Oaklander, JM BrownUnilateral nerve injury produces bilateral loss of distal innervation
Annals of Neurology Volume 55 Issue 5, Pages 639 – 644 Published Online: 12 Apr 2004

Review Abstract at: http://www3.interscience.wiley.com/journal/107639615/abstract

Pain produces mystery nerve loss - Mirror-image pain distresses researchers By William J. Cromie. Harvard News Office

This one is just an article but very interesting: Can be viewed at: http://www.news.harvard.edu/gazette/2004/05.06/01-pain.html (about research being done by Anne Louise Oaklander from Harvard Medical – same researcher from above Bio)

Study Finds Nerve Damage Can Affect Opposite Side Of Body. ScienceDaily. Retrieved October 25, 2008,

Review at: http://www.sciencedaily.com/releases/2004/04/040413003507.htm

Peter G. Martin & Jodie RatteyCentral fatigue explains sex differences in muscle fatigue

and contralateral cross-over effects of maximal contractions. Pflugers Arch - Eur J Physiol (2007) 454:957–969

Review 1^st page of article at: http://www.springerlink.com/content/wuk388384q671j64/fulltext.pdf?page=1

BL Chan, R Witt, AP Charrow, A Magee, R Mirror Therapy for Phantom Limb Pain

The New England Journal of Medicine. Volume 357:2206-2207 November 22, Number 21

Cross Education: Possible Mechanisms for the Contralateral Effects of Unilateral Resistance Training

Van Wingerden, J. P., Vleeming, A., Snijders, C. J., & Stoeckart, R. (1993). A functionalanatomical approach to the spine-pelvis mechanism: interaction between the biceps femoris muscle and the sacrotuberous ligament.

Vleeming, A., Pool-Goudzwaard, A. L., Stoeckart, R., van Wingerden, J. P., Snijders, C. J.,Vleeming, A., et al. (1995). The posterior layer of the thoracolumbar fascia. Its function in load transfer from spine to legs. Spine, 20(7), 753-758.

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Volume 76, Issue 6, Pages 816-819 (June 2011)

Can imagined whole-body rotations improve vestibular compensation?

Received 24 January 2011; accepted 10 February 2011. published online 14 March 2011.

Abstract

Unilateral damage to the labyrinth and the vestibular nerve cause rotational vertigo, postural imbalance, oculomotor disorders and spatial disorientation. Electrophysiological investigations in animals revealed that such deficits are partly due to imbalanced spontaneous activity and sensitivity to motion in neurons located in the ipsilesional and contralesional vestibular nuclei. Neurophysiological reorganizations taking place in the vestibular nuclei are the basis of the decline of the symptoms over time, a phenomenon known as vestibular compensation. Vestibular compensation is facilitated by motor activity and sensory experience, and current rehabilitation programs favor physical activity during the acute stage of a unilateral vestibular loss. Unfortunately, vestibular-defective patients tend to develop strategies in order to avoid movements causing imbalance and nausea (in particular body movements towards the lesioned side), which impedes vestibular compensation. Neuroanatomical evidence suggests a cortical control of postural and oculomotor reflexes based on corticofugal projections to the vestibular nuclei and, therefore, the possibility to manipulate vestibular functions through top-down mechanisms. Based on evidence from neuroimaging studies showing that imagined whole-body movements can activate part of the vestibular cortex, we propose that mental imagery of whole-body rotations to the lesioned and to the healthy side will help rebalancing the activity in the ipsilesional and contralesional vestibular nuclei. Whether imagined whole-body rotations can improve vestibular compensation could be tested in a randomized controlled study in such patients beneficiating, or not, from a mental imagery training. If validated, this hypothesis will help developing a method contributing to reduce postural instability and falls in vestibular-defective patients. Imagined whole-body rotations thus could provide a simple, safe, home-based and self-administered therapeutic method with the potential to overcome the inconvenience related to physical movements.

-------------------------------------------

Authors: Lee, Michael1; Carroll, Timothy J.1

Source: Sports Medicine, Volume 37, Number 1, 2007 , pp. 1-14(14)

Publisher: Adis International

Abstract:

Resistance training can be defined as the act of repeated voluntary muscle contractions against a resistance greater than those normally encountered in activities of daily living. Training of this kind is known to increase strength via adaptations in both the muscular and nervous systems. While the physiology of muscular adaptations following resistance training is well understood, the nature of neural adaptations is less clear. One piece of indirect evidence to indicate that neural adaptations accompany resistance training comes from the phenomenon of `cross education', which describes the strength gain in the opposite, untrained limb following unilateral resistance training. Since its discovery in 1894, subsequent studies have confirmed the existence of cross education in contexts involving voluntary, imagined and electrically stimulated contractions. The cross-education effect is specific to the contralateral homologous muscle but not restricted to particular muscle groups, ages or genders. A recent meta-analysis determined that the magnitude of cross education is 7.8% of the initial strength of the untrained limb. While many features of cross education have been established, the underlying mechanisms are unknown.

This article provides an overview of cross education and presents plausible hypotheses for its mechanisms. Two hypotheses are outlined that represent the most viable explanations for cross education. These hypotheses are distinct but not necessarily mutually exclusive. They are derived from evidence that high-force, unilateral, voluntary contractions can have an acute and potent effect on the efficacy of neural elements controlling the opposite limb. It is possible that with training, long-lasting adaptations may be induced in neural circuits mediating these crossed effects. The first hypothesis suggests that unilateral resistance training may activate neural circuits that chronically modify the efficacy of motor pathways that project to the opposite untrained limb. This may subsequently lead to an increased capacity to drive the untrained muscles and thus result in increased strength. A number of spinal and cortical circuits that exhibit the potential for this type of adaptation are considered. The second hypothesis suggests that unilateral resistance training induces adaptations in motor areas that are primarily involved in the control of movements of the trained limb. The opposite untrained limb may access these modified neural circuits during maximal voluntary contractions in ways that are analogous to motor learning. A better understanding of the mechanisms underlying cross education may potentially contribute to more effective use of resistance training protocols that exploit these cross-limb effects to improve the recovery of patients with movement disorders that predominantly affect one side of the body.

____________________________________________________________________________________

The conclusion here supports the contention that teaching a patient to lift with a "rigid" lumbar posture perhaps needs to be re-thought...sound familiar?

Biomechanics of Changes in Lumbar Posture in Static Lifting.
Biomechanics
Spine. 30(23):2637-2648, December 1, 2005.
Arjmand, Navid MSc; Shirazi-Adl, Aboulfazl PhD

Abstract:
Study Design. In vivo measurements and model studies are combined to investigate the role of lumbar posture in static lifting tasks.

Objectives. Identification of the role of changes in the lumbar posture on muscle forces, internal loads, and system stability in static lifting tasks with and without load in hands.

Summary of Background Data. Despite the recognition of the causal role of lifting in spinal injuries, the advantages of preservation or flattening of the lumbar lordosis while performing lifting tasks is not yet clear.

Methods. Kinematics of the spine and surface EMG activity of selected muscles were measured in 15 healthy subjects under different forward trunk flexion angles and load cases. Apart from the freestyle lumbar posture, subjects were instructed to take either lordotic or kyphotic posture as well. A kinematics-based method along with a nonlinear finite element model were interactively used to compute muscle forces, internal loads and system stability margin under postures, and loads considered in in vivo investigations.

Results. In comparison with the kyphotic postures, the lordotic postures increased the pelvic rotation, active component of extensor muscle forces, segmental axial compression and shear forces at L5-S1, and spinal stability margin while decreasing the passive muscle forces and segmental flexion moments.

Conclusion. Alterations in the lumbar lordosis in lifting resulted in significant changes in the muscle forces and internal spinal loads. Spinal shear forces at different segmental levels were influenced by changes in both the disc inclinations and extensor muscle lines of action as the posture altered. Considering internal spinal loads and active-passive muscle forces, the current study supports the freestyle posture or a posture with moderate flexion as the posture of choice in static lifting tasks

Contralateral effects of unilateral strength training : evidence and possible mechanisms

CARROLL Timothy J. (1) ; HERBERT Robert D. (2) ; MUNN Joanne (2) ; LEE Michael (1) ; GANDEVIA Simon C. (3) ;

Author(s) Affiliation(s)

(1) Health and Exercise Science, School of Medical Sciences, University of New South Wales, AUSTRALIE

(2) School of Physiotherapy, University of Sydney, AUSTRALIE

(3) Prince of Wales Medical Research Institute, University of New South Wales, Sydney, New South Wales, AUSTRALIE

Abstract

If exercises are performed to increase muscle strength on one side of the body, voluntary strength can increase on the contralateral side. This effect, termed the contralateral strength training effect, is usually measured in homologous muscles. Although known for over a century, most studies have not been designed well enough to show a definitive transfer of strength that could not be explained by factors such as familiarity with the testing. However, an updated meta-analysis of 16 properly controlled studies (range 15-48 training sessions) shows that the size of the contralateral strength training effect is ∼8% of initial strength or about half the increase in strength of the trained side. This estimate is similar to results of a large, randomized controlled study of training for the elbow flexors (contralateral effect of 7% initial strength or one-quarter of the effect on the trained side). This is likely to reflect increased motoneuron output rather than muscular adaptations, although most methods are insufficiently sensitive to detect small muscle contributions. Two classes of central mechanism are identified. One involves a "spillover" to the control system for the contralateral limb, and the other involves adaptations in the control system for the trained limb that can be accessed by the untrained limb. Cortical, subcortical and spinal levels are all likely to be involved in the "transfer," and none can be excluded with current data. Although the size of the effect is small and may not be clinically significant, study of the phenomenon provides insight into neural mechanisms associated with exercise and training.

Journal Title

Journal of applied physiology ISSN 8750-7587 CODEN JAPHEV

Source

2006, vol. 101, no5, pp. 1514-1522 [9 page(s) (article)] (90 ref.)

Contralateral effects of unilateral resistance training: a meta-analysis

Auteur(s) / Author(s)

MUNN J. ; HERBERT R. D. ; GANDEVIA S. C. ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

School of Physiotherapy, The University of Sydney, Prince of Wales Medical Research Institute and The University of New South Wales, Sydney 2052, AUSTRALIE

Abstract

It is often claimed that strength training of one limb increases the strength of the contralateral limb, but this has not been demonstrated consistently, particularly in well-controlled studies. The aim was to quantitatively combine the results of other studies on the effects of unilateral training on contralateral strength in humans to provide an answer to this physiological question. We analyzed all randomized controlled studies of voluntary unilateral resistance training that used training intensities of at least 50% of maximal voluntary strength for a minimum of 2 wk. Studies were identified by computerized and hand searches of the literature. Data on changes in strength of contralateral and control limbs were extracted and statistically pooled in a meta-analysis. This approach allows conclusions to be based on a statistically meaningful sample size, which might be difficult to achieve in other ways. Seventeen studies met the inclusion criteria, and 13 provided enough data for statistical pooling. The contralateral effects of strength training reported in individual studies varied from -2.7 to 21.6% of initial strength. The pooled estimate of the effect of unilateral resistance training on the maximal voluntary strength of the contralateral limb was 7.8% (95% confidence interval: 4.1-11.6%). This was 35.1% (95% confidence interval: 20.9-49.3%) of the effect on the trained limb. Pooling of all available data shows that unilateral strength training produces modest increases in contralateral strength.

Journal Title

Journal of applied physiology ISSN 8750-7587 CODEN JAPHEV

Source

2004, vol. 96, no5, pp. 1861-1866 [6 page(s) (article)] (44 ref.)

Unilateral arm strength training improves contralateral peak force and rate of force development

Adamson, M. and MacQuaide, N. and Helgerud, J. and Hoff, J. and Kemi, O.J. (2008) Unilateral arm strength training improves contralateral peak force and rate of force development. European Journal Of Applied Physiology 103(5):pp. 553-559.

Abstract

Neural adaptation following maximal strength training improves the ability to rapidly develop force. Unilateral strength training also leads to contralateral strength improvement, due to cross-over effects. However, adaptations in the rate of force development and peak force in the contralateral untrained arm after one-arm training have not been determined. Therefore, we aimed to detect contralateral effects of unilateral maximal strength training on rate of force development and peak force. Ten adult females enrolled in a 2-month strength training program focusing of maximal mobilization of force against near-maximal load in one arm, by attempting to move the given load as fast as possible. The other arm remained untrained. The training program did not induce any observable hypertrophy of any arms, as measured by anthropometry. Nevertheless, rate of force development improved in the trained arm during contractions against both submaximal and maximal loads by 40-60%. The untrained arm also improved rate of force development by the same magnitude. Peak force only improved during a maximal isometric contraction by 37% in the trained arm and 35% in the untrained arm. One repetition maximum improved by 79% in the trained arm and 9% in the untrained arm. Therefore, one-arm maximal strength training focusing on maximal mobilization of force increased rapid force development and one repetition maximal strength in the contralateral untrained arm. This suggests an increased central drive that also crosses over to the contralateral side.

The contralateral effect after a single-leg coordinative training program

K. Oehlert - Universitätsklinikum Schleswig-Holstein, Campus Kiel, Klinik für Orthopädie, Kiel

J. Heine - Kiel

H. Krause - Kiel

D. Varoga - Kiel

H. Rieckert - Kiel

J. Hassenpflug - Kiel

Introduction

Motor coordination, especially balance abilities, is essential for joint stability and movement patterns. Recent studies have shown positive effects on the contralateral untrained side after unilateral strength training. The role of unilateral coordinative training programs has not yet been determined. The aim of the study was to evaluate the contralateral effect of a single-leg coordinative training program on the untrained side.

Material and Methods

61 healthy subjects participated in this prospective intervention study. 32 of them accomplished a four-week long comprehensive coordinative training program on the dominant leg. Training instruments were half sphere ankle discs and the Thera-Band®Stability Trainer. The remaining 29 subjects served as a control group. The coordinative abilities were tested with the Biodex Stability System®.

Results

The coordinative abilities of both the trained and untrained leg increased after the coordinative training. The increase in coordination was significant for both legs of the exercise group as measured by the Biodex Stability System®.

Discussion

Our results indicate that single-leg coordinative training has both an effect on the trained leg and the contralateral leg. It seems as though that patients practice with their non-affected leg coordinative exercises and their affected leg profits indirectly. If the results of the study were confirmed in injured individuals, patients could circumvent the negative effects of immobilization or limited weight-bearing after an injury.

Cross-training effects of a proprioceptive neuromuscular facilitation exercise programme on knee musculature

Nikolaos D. Kofotolisa and Eleftherios Kellis, a,

aLaboratory of Neuromuscular Control and Therapeutic Exercise, Department of Physical Education and Sport Science at Serres, Aristotle University of Thessaloniki, TEFAA Serres, Agios Ioannis, 62110 Serres, Greece

Twenty-three males were assigned to a PNF group (n=12) or a control group (n=11).

Interventions

The PNF program included training of the knee extensor and flexor muscles for a period of 8 weeks, exercising three times a week. PNF training included performance of knee movements through range of motion against manual resistance.

Main outcome measures

Isokinetic torque and fatigue of the knee flexors and extensors at 60, 180 and 300° s−1 were assessed prior to and immediately after the training period.

Results

Analysis of variance designs indicated that the PNF group demonstrated significant gains (9.9%) in knee extension torque of the contralateral leg. In contrast, no cross-training effects on peak flexion torque was observed.

Conclusions

Cross-training effects after PNF exercise were restricted to the knee extensor muscles. Such effects may be important when the aim of a rehabilitation program is to improve the knee extensor muscle function of an immobilized contralateral leg.

The Benefit of a Single-Leg Strength Training Program For the Muscles Around the Untrained Ankle

A Prospective, Randomized, Controlled Study

Benjamin S. Uh, MD, Bruce D. Beynnon, PhD*, Bryce V. Helie, Denise M. Alosa, MS, ATC and Per A. Renstrom, MD, PhD

McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, Vermont

* Address correspondence and reprint requests to Bruce D. Beynnon, PhD, The University of Vermont McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, Robert T. Stafford Hall, Burlington, VT 05405-0084

Severe ankle injuries can require extended periods of immobilization that adversely affect the strength of the ankle muscles. We have investigated a single-leg strength training program of the muscles surrounding the ankle to determine if it produces a crossover benefit for the contralateral ankle muscles. Twenty subjects without any history of ankle injuries were randomly divided into a control and a training group. Both groups underwent isokinetic testing of the ankle muscles at the beginning and end of an 8-week period. The control group maintained normal activities between the tests. Half of the training group trained the dominant leg only and the other half trained the nondominant leg only for the 8-week period, three times per week. The subjects who trained the dominant leg improved peak torque values by 8.5% in the trained leg and 1.5% in the untrained leg. Similarly, the subjects who trained the nondominant leg improved peak torque values by 9.3% in the trained leg and 3.5% in the untrained leg. In contrast, the control group showed no significant change in peak torque, power, or endurance between the initial and final tests. With improvements in peak torque as high as 40% in the trained leg and a crossover benefit of 19% in the untrained leg in eccentric inversion, this strength training technique deserves further investigation in an injured population where the benefits may be more substantial.

The effect of strength training in muscle and nerve is memorized and reinforced by retraining.

Author;OMORI HAJIME(Univ. of Tsukuba, Inst. of Health and Sport Sci.) WATANABE AKIHITO(Univ. of Tsukuba, Graduate School) TSUKUDA FUMIKO(Univ. of Tsukuba, Inst. of Health and Sport Sci.) TAKAHASHI HIDEYUKI(Kokuritsusupotsukagakuse) KUME TOSHIRO(Univ. of Tsukuba, Graduate School) SHIRAKI HITOSHI(Univ. of Tsukuba, Inst. of Health and Sport Sci.) OKADA MORIHIKO(Univ. of Tsukuba, Inst. of Health and Sport Sci.) ITAI YUJI(Univ. of Tsukuba, Inst. of Clin. Med.) KATSUTA SHIGERU(Toa Univ.)

Journal Title;Japanese Journal of Physical Fitness and Sports Medicine

Journal Code:Z0388B

VOL.49;NO.3;PAGE.385-392(2000)

Pub. Country;Japan

Language;Japanese

Abstract;The purpose of this study was to prove the hypothesis that the effect of strength training is memorized and reinforced by retraining. Untrained university-age men participated in this training program. The retraining leg was subjected to 5 weeks of isometric training, 17 weeks of detraining and 5 weeks of retraining in knee extension. The contralateral training leg was subjected to 5 weeks of isometric training during the same period as the retraining phase of the retraining leg. Maximal isometric torque of knee extension increased after the 5-week training and remained at the trained level during the 17-week detraining period. Torque gain by retraining of the retraining leg was 2.6 times greater than that of the contralateral training leg. These changes in isometric torque corresponded with changes in iEMG of the vastus lateralis. The cross-sectional area of the quadriceps femoris muscie did not change with training. Results support the hypothesis that the effect of strength training is memorized and reinforced by retraining. In addition, results show that these adaptations would be explained by recruitment and rate coding of motor units. (author abst.)

“Research on the effects of motor imagery and mental training to motor performance show that repeated motor imagery can lead to increased muscular strength (Yue and Cole 1992), improvements in the learning of new motor skills, (Hall et al 92, Yaguez et al 98), and improved form it's in sports (eg Lejune et al 94). The learning effects are thought to arise at cortical programming levels of the motor system not from neural changes at the execution level.” Sleep and Dreaming Ed. Edward F. Pace-Schott. Page 98

“Yue and Cole (92) found an increase it peak abduction force by 22% when participants were asked to image maximal isometric contractions of the abductor digit minimi muscle on the little finger.” Advances in Sport Psychology ED By Thelma S. Horn, page 302.

“A classic study (well, classic to me, at least) by Yue and Cole in 1992 found that imagined finger abduction regimens increased the subjects’ strength by an average of 22%; actually doing the same regimen physically that the other test group was doing in their imaginations increased strength by an average of 30%. Enoka (1997) outlines some of the long-term neural consequences of repetitive action patterns, including effects at a wide range of levels (cellular to systemic) and locations (such as in the motor cortex, in the muscles themselves, and in related muscles). “ Neuroanthropology.net

Enoka, R. M. 1997. Neural adaptations with chronic physical activity. Journal of Biomechanics 30(5):447-55.

Yue G., and K. J. Cole. 1992. Strength increases from the motor program: comparison of training with maximal voluntary and imagined muscle contractions. Journal of Neurophysiology 67(5): 1114-23.

The effect of short-term strength training on human skeletal muscle: the importance of physiologically elevated hormone levels

Authors: Hansen S.1; Kvorning T.1; Kjær M.2; Sjøgaard G.3

Scandinavian Journal of Medicine & Science in Sports, Volume 11, Number 6, December 2001 , pp. 347-354(8)

Abstract:

The effect of strength training and endogenously elevated hormone levels (plasma testosterone, growth hormone (GH) and cortisol) was studied in 16 young untrained males, divided into an arm only training group, A, and a leg plus arm training group, LA, in order to increase circulating levels of anabolic hormones. Both groups performed the same one-sided arm training for 9 weeks, twice a week. Group A trained only one arm (AT), the contralateral arm serving as control (AC), whereas group LA additionally trained their legs following the training of the one arm (LAT), with the contralateral arm serving as control (LAC). In spite of the attempt to match the two groups, the initial isometric arm strength was 20–25% lower for group LA compared to group A (significant for the arm to be trained). Isometric strength increased significantly in LAT and LAC by 37% and 10%, respectively, while the 9% and 2% increases in AT and AC, respectively, remained insignificant. Isokinetic strength increased at one out of three velocities tested for the trained arm relative to the untrained arm in both group A and group LA (P<0.05). Functional strength increased significantly by 20% in LAT, 18% in LAC, 19% in AT, and 17% in AC. Hormonal responses were monitored during the first and last training sessions. Resting hormone levels remained unchanged for both groups. However, during the first training session plasma testosterone as well as plasma cortisol increased significantly in group LA but not in group A. Plasma GH rose in all exercise tests, except during the last test in group LA, but was significantly higher in group LA than in group A in the first training session. In conclusion, a larger relative increase in isometric strength was found in the group having the highest hormonal response. However, due to the initial difference in isometric strength caution must be taken with the interpretation of this finding, which may only indicate a possible link between anabolic hormones and muscle strength with training.

Neuro-Physiological Adaptations Associated with Cross-Education of Strength Journal Brain Topography

ISSN 0896-0267 (Print) 1573-6792 (Online)

Volume 20, Number 2 / December, 2007, Pages 77-88

Subject Collection Biomedical and Life Sciences

SpringerLink Date Friday, October 12, 2007

Jonathan P. Farthing1 , Ron Borowsky2, Philip D. Chilibeck1, Gord Binsted1 and Gordon E. Sarty2(1) College of Kinesiology, University of Saskatchewan, 87 Campus Drive, Saskatoon, SK, Canada, S7N 5B2

(2) Cognition and Neuroscience Programs, Department of Psychology, College of Arts and Science, University of Saskatchewan, Saskatoon, SK, Canada

Abstract Cross-education of strength is the increase in strength of the untrained contralateral limb after unilateral training of the opposite homologous limb. We investigated central and peripheral neural adaptations associated with cross-education of strength. Twenty-three right-handed females were randomized into a unilateral training group or an imagery group. A sub-sample of eight subjects (four training, four imagery) was assessed with functional magnetic resonance imaging (fMRI) for patterns of cortical activation during exercise. Strength training was 6 weeks of maximal isometric ulnar deviation of the right arm, four times per week. Peak torque, muscle thickness (ultrasound), agonist–antagonist electromyography (EMG), and fMRI were assessed before and after training. Strength training was highly effective for increasing strength in trained (45.3%; P < 0.01) and untrained (47.1%; P < 0.01) limbs. The imagery group showed no increase in strength for either arm. Muscle thickness increased only in the trained arm of the training group (8.4%; P < 0.001). After training, there was an enlarged region of activation in contralateral sensorimotor cortex and left temporal lobe during muscle contractions with the untrained left arm (P < 0.001). Training was associated with a significantly greater change in agonist muscle EMG pooled over both limbs, compared to the imagery group (P < 0.05). These results suggest that cross-education of strength may be partly controlled by adaptations within sensorimotor cortex, consistent with previous studies of motor learning. However, this research demonstrates the involvement of temporal lobe regions that subserve semantic memory for movement, which has not been previously studied in this context. We argue that temporal lobe regions might play a significant role in the cross-education of strength.

Neural mechanisms are the most important determinants of strength adaptations.

Proposition for Debate - by Amanda Broughton

Introduction

This debate addresses factors influencing an increase in muscle strength. This debate can be simply affirmed by the fact that we have all witnessed improvement in performance of a repeated strength test without evidence of muscle hypertrophy. Two definitions to clarify any misunderstandings are:

Strength

"The greatest amount of force that muscles can produce in a single maximal effort" (Lamb, 1984).

Neural mechanisms

"motor unit activation (recruitment, discharge rate), synchronization, and cross education" (Enoka and Fuglevand, 1993).

Literature suggests that physical training causes adaptations in the brain and spinal cord and that the ability of humans to recruit motor units increases with training (Lamb, 1984). Neural factors involved in muscle strength are: activation of motor units (frequency and quantity), involvement of afferent and efferent pathways, synchronization, and cross-education.

In addition to neural factors, we must consider other factors involved in muscle strength. Increased muscle cross sectional area (CSA) has a strong relationship with muscle strength (Lamb, 1984). Muscle length, rate of change of muscle length, and the alignment of the muscle with respect to the axis of joint rotation (Enoka and Fuglevand, 1993) are also involved in determining the strength of a muscle upon testing.

Background Knowledge

Considering all factors influencing muscle strength, it is important to ensure that a standard test procedure is used to evaluate muscle strength. As such, a maximal voluntary isometric contraction (MVIC) is the preferred option (Rutherford and Jones, 1986, cited in Enoka and Fuglevand, 1993). This minimizes the influence of neural components associated with muscle co-ordination, and removes influence from rate of change of a muscle. It also requires that muscle length and joint position are the same for each test. Mechanical and electromyographic (EMG) measurements are taken during the contraction to evaluate changes to the neuromuscular apparatus. EMG measurements are used as an indicator of motor unit activity, which gives an indication of the muscle force generated (Enoka and Fuglevand, 1993. Komi (1986) points out that the EMG recordings do not indicate whether the increased motor unit activity comes from the cortical or reflex sources, or from both.

Lawrence and DeLuca (1983, cited in Enoka and Fuglevand, 1993), suggest that EMG measurements during a MVIC are known to be somewhat unreliable. Howard and Enoka (1991, cited in Enoka and Fuglevand, 1993) found that on three repetitions of a knee extensor MVIC the average EMG varied substantially while the force remained constant. The authors therefore cautioned against using EMG as a direct representation of the activation of motor units of a muscle at high forces such as during an MVIC. The EMG recordings from surface electrodes are a result of summation of randomly occurring action potentials from numerous motor units. According to an unpublished dissertation by Fuglevand (1989, cited in Enoka and Fuglevand, 1993, p222), a motor unit action potential is influenced by:

the number and size of fibers innervated by the motor unit,

the spatial orientation of the fibers relative to the electrode,

the electrode configuration and dimensions,

the conduction velocity of the fiber action potential,

the spatial relationship of the electrode to the innervation zone, and the length of the muscle fibers.

Neural Mechanisms

The motor unit consists of the motor nerve cell (neuron) that originates in the spinal cord (indicated by '3' in figure 1) and all the muscle fibers it supplies. All fibers in a motor neuron are of the same fiber type and are distributed throughout the muscle (Lamb, 1984). Slow twitch fibers are usually recruited first, and once a motor unit is activated, all muscle fibers in that unit are activated equally. To modulate muscle force, motor units change their firing frequency, and the number of active motor units changes. The motor units do not all fire in unison, except under conditions of maximal stimulation. "The CNS remains capable of fully activating all motor units to respond with maximum force under conditions of extreme contractile failure" (Thomas, Woods, and Bigland-Ritchie 1989, p. 1835, cited in Enoka and Fuglevand, 1993).

A motor unit is influenced by reflex pathways, muscle spindle input, input from higher and lower spinal cord levels, and from nerves on the opposite side of the cord as shown in figure 2 (Lamb, 1984). According to Enoka and Fuglevand (1993) many authors suggest that facilitation of the MVIC is due to the descending command being supplemented with afferent feedback. Komi (1986) suggests that training intensity must be periodically varied and/or progressively increased to maintain an increase in maximal neural activation. During detraining, or immobilisation, the neural input is decreased resulting in a decreased force production and muscle atrophy.

Research Findings

Muscle Strength

Significant gains in muscle strength have been shown following short periods of resistance training, which are generally regarded as being too short to elicit morphological changes in the muscle (Moritani and deVries, 1979). It would therefore seem that this strength increase is due to an ability to better activate the muscle. Over time the muscle activation plateaus and CSA increases, suggesting that after a time, hypertrophy is the more significant factor in increased strength. Various suggestions regarding these two factors are explored below. (See Figure 3).

Neural Adaptation

"Neural adaptation after resistance training has been inferred on the basis of several studies reporting increases in muscle strength with little or no change in cross sectional area of the muscle." (Bandy et al, 1990, p.252). Most research into neural adaptations after resistance training looks mainly at motor unit activation by using EMG. It is widely accepted that increases in EMG is a result of increased firing frequency of motor units in combination with an increased recruitment of motor units.

Cross education is evidenced by an increased strength in the contralateral limb and is likely due to cross talk between nerves in the spinal cord from one side to the other. Moritani and deVries (1979) reported an increase in MVIC force of 36% in isometrically trained elbow flexors versus a 25% increase in the contralateral untrained limb. The changes in the untrained limb occurred without changes in CSA or enzyme activities. Butler and Darling (1990, cited in Enoka and Fuglevand, 1993) found an increase in EMG in the contralateral untrained limb. Subjects have exhibited a lower single limb MVIC when both limbs are active simultaneously than when tested in isolation (Howard and Enoka, 1991, cited in Enoka and Fuglevand, 1993). It could be postulated that this is due to cross talk from the contralateral side during a single limb effort that is not present to the same extent during a bilateral task.

Research Update - New Findings

Central Nervous System

Increases in strength have been shown when a subject shouts during exertion, or if a pistol is fired near the subject shortly before the test procedure (Ikai and Steinhaus, 1961, cited in Lamb, 1984). Similar strength changes have also been noted when the subject is given hypnotic suggestions of strength (Morgan, 1972, cited in Lamb, 1984). Yue and Cole (1992, cited in Enoka and Fuglevand, 1993) observed an increase in MVIC and EMG following imagery.

Electrical stimulation

It has been shown that a voluntary contraction is not a strong as a contraction stimulated electrically (Ikai and Yabe, 1969, cited in Lamb, 1984, and Stephens and Taylor, cited in Lamb, 1984).

Electrical stimulation - training

It has been shown that strength development can be achieved through electrical stimulation of a muscle, however the strength gains from this method of training are less than those noted in a voluntary training program (Massey, 1964, cited in Moritani and deVries, 1979, and Nowakowska, 1962, cited in Moritani and deVries, 1979). This is likely due to the lack of involvement of the motor pathways in electrically stimulated training. Lyle and Rutherford (1998) however, found no significant difference between strength gains in adductor pollicis of voluntary versus stimulated contractions. The large gains shown in stimulated training argues against central adaptations as a major contributor to the strength increases following training.

EMG

In most studies, the EMG/force slope initially remained the same as in the pre-trial testing with an increase in muscle activation (EMG values). After a few weeks resistance training the EMG slope started to decrease, indicating muscle hypertrophy gradually becoming integrated in the strength increase and the rapidly increasing muscle activation slowed to a lesser rate.

Disproportionate CSA increase

After a number of weeks of resistance training, an increase in CSA can be measured. This increase is proportionally smaller than the increase in MVIC (Narici et al, 1989, cited in Enoka and Fuglevand, 1993). Nonetheless, CSA is the single best predictor of muscle strength. Larger muscles have a greater amount of actin and myosin, therefore a greater number of cross bridges, which results in a greater potential for force production during contraction.

Motor Unit Synchronisation

Strength training can increase motor unit synchronization. Friedeboldet et al (1957, cited in Komi, 1986) was among the first to suggest that, in particular, the early part of strength training is associated with an increase in motor unit synchronization. Komi goes on to suggest two possible explanations for this increased synchronization.

The dendrites of alpha-motor neurons receive increased input from sensory fibers, and

The higher motor centers increase their descending activity.

Specificity

Rasch and Morehouse (1957, cited in Moritani and deVries, 1979) demonstrated strength gains from a six-week training program in tests where muscles were used in a familiar way, but not when unfamiliar test procedures were involved. This suggests that larger test results were mainly due to skill acquisition.

Muscle Hypertrophy

Muscle hypertrophy seems mostly to result after training periods greater than six weeks, and is predominantly related to fast rather than slow twitch fibers (Bandy et al, 1990). Komi (1986) suggests that the increased alpha-motor neuron activation with motor neuron synchronization may stimulate hypertrophic factors that are expected to result after a period of progressively increasing strength training.

Clinical Implications

When considering a resistance training program, it is important to understand what you are improving at various stages of the program. Initially improvement will be due to neural adaptation. To maximise this potential, the program needs to be modified and/or progressed regularly so that neural adaptation does not plateau too soon. It is also necessary to consider the phenomenon of specificity. The muscle will improve in performing the task it is trained to do, there is minimal crossover to other tasks, and so a variety of contraction modes and joint positions will need to be employed for a more comprehensive program. Ensure that the task that is being trained will have functional relevance for day-to-day living. After a time hypertrophy will become evident. To maintain muscle strength and bulk, the training program needs to continue and be progressed and modified.

The phenomenon of bilateral deficit needs to be considered. A muscle can generate a greater force if worked in isolation. Unilateral training will therefore result in a more rapid strength increase than a bilateral task. Considering specificity, it may be necessary to train both ways.

Conclusion

Initial changes to muscle strength are due to neural factors (motor unit activation, firing frequency, input from the opposite side of the spinal cord, input from muscle spindles and reflexes, input from lower and higher spinal cord levels). Over time, the increased rate of neural activation decreases to a slower rate and muscle hypertrophy commences (this is postulated to be stimulated by the neural system). The muscle CSA increases with continued training. This also results in increased strength. The CSA does not increase to the same extent as the muscle strength. The total strength increase is a combination of increased neural activation and muscle hypertrophy.

References

Bandy WD, Lovelace-Chandler V, and McKitrick-Bandy B (1990)

Adaptation of skeletal muscle to resistancetraining. Journal of Orthopaedic and Sports Physical Therapy 12(6):248-255

Enoka RM and Fuglevand AJ (1993)

Chapter 8: Neuromuscular basis of the maximum voluntary forcecapacity of muscle. In Grabnier MD (Ed): Current issues in Biomechanics.Champaign, IL: Human Kinetics Books.

Komi PV (1986)

Training of muscle strength and power: interaction of neuromotoric, hypertrophic, and mechanical factors. International Journal of Sports Medicine 7:10-15

Lamb DR (1984)

Physiology of Exercise: Responses and Adaptations (2nd ed). New York: MacMillan Publishing Company.

Lyle N and RutherfordOM (1998)

A comparison of voluntary versus stimulated strength training of the human adductor pollicis muscle. Journal of Sports Sciences 16(3):267-270 (Abstract only viewed)

Moritani T and deVries HA (1979)

Neural factors versus hypertrophy in the time course of musclestrength gain. American Journal of Physical Medicine 58(3):115-130

Plowman SA and Smith DL (1997)

Exercise Physiology: For Health, Fitness, and Performance. Boston, MA: Allyn and Bacon.

DeschenesMR, Maresh CM, and Kraemer WJ (1994)

The neuromuscular junction: structure, function, and its role in the excitation of muscle. Journal of Strengthand Conditioning Research 8(2):103-109

Higbie EJ, CuretonKJ, Warren GL, and Prior BM (1996)

Effects of concentric and eccentrictraining on muscle strength, cross-sectional area, and neural activation.Journal of Applied Physiology 81(5):2173-2181

Enoka RM (1988)

Musclestrength and its development. New perspectives. Sports Medicine 6(3):146-168

Seger JY, Arvidsson B, and Thorstensson A (1998)

Specific effects of eccentric and concentric training on muscle strength and morphology in humans. European Journal of Applied Physiology and Occupational Physiology 79(1):49-57

Zhou S (2000)

Chronicneural adaptations to unilateral exercise: mechanisms of cross education. Exerciseand Sports Science Reviews 8(4):177-184

December 9, 2007

Mindful Exercise

By CHRISTOPHER SHEA

Simply by telling 44 hotel maids that what they did each day involved some serious exercise, the Harvard psychologist Ellen Langer and Alia J. Crum, a student, were apparently able to lower the women’s blood pressure, shave pounds off their bodies and improve their body-fat and “waist to hip” ratios. Self-awareness, it seems, was the women’s elliptical trainer.

At the start of the study, Langer and Crum quizzed 84 maids at seven carefully matched hotels about how much exercise they got. Fully a third of the women said they got no exercise at all, while two-thirds said they did not work out regularly. Langer and Crum took several measures of the women’s basic fitness levels, which indicated that they, indeed, had the poor health of basically sedentary people. Then just over half the women were told an unfamiliar truth: cleaning 15 rooms daily — pushing recalcitrant vacuum cleaners, scrubbing tubs, pulling sheets — constitutes more than enough activity to meet the surgeon general’s recommendation of a half-hour of physical activity daily. The researchers even provided specifics: 15 minutes of scrubbing burns 60 calories, 15 minutes of vacuuming burns 50. The basic message and the details were then posted in the maids’ lounges in the hotels where the 44 women worked, to serve as reminders, while a control group was left in the dark.

A month later, Langer and Crum checked back with the women to find, as they reported in the February issue of Psychological Science, remarkable results. The average study-group maid had lost 2 pounds, while her systolic blood pressure had dropped by 10 points; by all measures the 44 women “were significantly healthier.” Yet there were no reported changes in behavior, only in mind-set, with the vast majority of the women now considering themselves regular exercisers. Langer sees the study as a lesson in the importance of mindfulness, long a subject of her research, and which need not involve Buddhism or meditation, she stresses. “It’s about noticing new things; it’s about engagement,” she says.

But for the study’s white-collar readers, a corollary to its results might be dispiriting: Made freshly aware — mindful — of just how sedentary their work lives are in contrast to a housekeeper’s, might they not suffer a corresponding decline in health?

____________________________________________________________________

Healthy mind, healthy body

· Ben Goldacre

· The Guardian,

· Saturday August 23 2008

Belief is half the battle with housework.

What I particularly enjoy is the spectacle of fat people - ideally drinking beer - watching television, while somewhere on the other side of the world citizens of all nations are getting some nice exercise in the Olympics (throwing javelins, jumping over metal bars, climbing lamp-posts with banners, and running away from the water cannon).

These are the people I imagine paying for gyms they never visit, while I am cheerfully cycling to work and carrying the shopping up the stairs.

But can obsessing over sport actually improve your health? Slightly, possibly, if you've got something to work with.

Alia Crum and Ellen Langer from Harvard psychology department took 84 female hotel attendants in seven hotels. They were cleaning an average of 15 rooms a day, each requiring half an hour of walking, bending, pushing, lifting, and carrying. These women were clearly getting a lot of good exercise, but they didn't believe it: 66.6% of them reported not exercising regularly, and 36.8% said they didn't get any exercise at all.

Their health, measured by things such as weight, body fat, body mass index, waist-to-hip ratio and blood pressure, was related to their perceived amount of exercise, rather than the actual amount of exercise they got, and this, so far, isn't very unusual.

A classic study of 7,000 adults found that perceived health is a better predictor of death than actual health, and another looking at elderly people found that those who perceive their health to be poor are six times more likely to die than those who perceive their health to be excellent, regardless of how healthy they actually are. Once again this goes to show the danger of relying on self-report data for health research.

But it gets better. Crum and Langer then divided the hotel workers into two groups (by hotel). One group got a one hour presentation on what a fabulous amount of exercise they were getting, how they were meeting and clearly exceeding recommendations for an active lifestyle.

They were given information sheets, in English and Spanish, showing the calorie burn for activities like vacuuming, or cleaning a bathroom, and the researchers even put notices up in communal areas explaining what excellently healthy exercise their work was. The other group was left alone.

Four weeks later the researchers measured everything again. The group who had been tutored about the health benefits of their work now perceived that they did more exercise than before - unsurprisingly - while the group who were left alone didn't change. Neither group had changed their actual levels of activity.

But amazingly, despite no change in actual exercise levels, in the intervention group, simply being told about the value of what they were already doing caused a significant change for the better on every single one of the objective health measures recorded: weight, body fat, body mass index, waist-to-hip ratio and blood pressure.

It's an outrage. Maybe mindset alone can influence metabolism and the benefits of exercise: perhaps this experiment shows, essentially, the placebo benefits of exercise. Maybe the cleaners changed their behaviour, or their diets, in ways that the researchers didn't pick up, perhaps they had more spring in their step, tipping the scales in their favour. And maybe it doesn't actually matter what caused the change, as long as we can exploit it: because the links between body and mind are far more fascinating than any pill peddler would ever have you believe.

· Ben Goldacre's Radio 4 documentary series Placebo is available online at qurl.com/placebo

Training with unilateral resistance exercise increases contralateral strength

Joanne Munn,1 Robert D. Herbert,1 Mark J. Hancock,1 and Simon C. Gandevia2

1School of Physiotherapy, The University of Sydney, Lidcombe; and 2Prince of Wales Medical Research Institute, University of New South Wales, Randwick, Australia

Submitted 11 May 2005 ; accepted in final form 10 July 2005

Evidence that unilateral training increases contralateral strength is inconsistent, possibly because existing studies have design limitations such as lack of control groups, lack of randomization, and insufficient statistical power. This study sought to determine whether unilateral resistance training increases contralateral strength. Subjects (n = 115) were randomly assigned to a control group or one of the following four training groups that performed supervised elbow flexion contractions: 1) one set at high speed, 2) one set at low speed, 3) three sets at high speed, or 4) three sets at low speed. Training was 3 times/wk for 6 wk with a six- to eight-repetition maximum load. Control subjects attended sessions but did not exercise. Elbow flexor strength was measured with a one-repetition maximum arm curl before and after training. Training with one set at slow speed did not produce an increase in contralateral strength (mean effect of –1% or –0.07 kg; 95% confidence interval: –0.42–0.28 kg; P = 0.68). However, three sets increased strength of the untrained arm by a mean of 7% of initial strength (additional mean effect of 0.41 kg; 95% confidence interval: 0.06–0.75 kg; P = 0.022). There was a tendency for training with fast contractions to produce a greater increase in contralateral strength than slow training (additional mean effect of 5% or 0.31 kg; 95% confidence interval: –0.03–0.66 kg; P = 0.08), but there was no interaction between the number of sets and training speed. We conclude that three sets of unilateral resistance exercise produce small contralateral increases in strength.

The Shocking Nervous System!
by Chad Waterbury

Within the realm of training for greater strength, muscle mass, and endurance lies an area of science that remains relatively untapped: Neuroscience. It's indeed the uncharted waters in the vast ocean of the science and practice of resistance training. That's because so little is known about how the nervous system actually works.

Indeed, neuroscientists have yet to figure out how information in your brain is stored, processed, and retrieved. What exactly does that mean, anyway? It means we're not sure how your brain stores the phone number from that busty fitness bunny you met at the gym.

And when you need to recall her number because your old man left you the keys to his lime green Prius, we don't know how your brain is doing it. A few neuroscientists have a few muddy ideas, but there are still too many unknowns to clean and jerk those neural processes out of ambiguity.

So it's not surprising to learn that little is known about the relationship between the nervous system's control of skeletal muscle and how we can improve its function to build bigger muscles and bigger lifts.

But don't fret yet, Brett. Neurologists have accumulated a pretty respectable sample of studies over the last 50 years that help elucidate just how damn powerful your brain, spinal cord, and associated neurons really are to control and develop your strength and muscles. So I'm here to take you through some landmark neuroscience studies that make me drool like a perv at a peepshow.

I drool, yes I do. I drool because I know the next few decades are going to uncover my postulate that the nervous system is what's holding us back from developing strength and muscle beyond our wildest dreams.

Why I Believe The Nervous System is the Key

1. Nerve Controls Muscle — You have muscles that are classified as fast or slow. These muscles are matched up with nerves that are either fast or slow, too. So, by nature, a fast muscle has a fast nerve, and a slow muscle has a slow nerve.

But what happens when you pull a fast nerve out of its muscle and insert the fast nerve into a slow muscle? The muscle takes on fast characteristics. Voila! This process, known as cross innervation, demonstrates that nerve controls muscle. We can thank Eccles and his colleagues, along with Salmons and Sreter, for these demonstrations because their studies are probably the most significant demonstrations of the power that nerves have over muscles. (1, 2)

It wasn't, however, until 1998 before this concept was taken a step further. Before I get to the next study and what it demonstrated, I want to give you a brief lesson in the physiology of muscle hypertrophy.

New proteins that cause hypertrophy are produced in the nucleus of your muscle cells. The intent of resistance training is to break down muscle proteins so your body will send a signal to create more proteins. Over the course of months, this creation and insertion of new proteins in your muscles is what causes visible muscle growth. And what enters the nucleus to signal new protein formation is known as a transcription factor.

In 1998, Chin et al demonstrated that the rate of nerve firing into the muscle determined whether fast or slow muscle proteins were formed. During periods of slow nerve activity, a specific transcription factor (NFAT) enters the nucleus and induces slow fiber formation. (3) My iteration is this: when NFAT enters the nucleus of a muscle, slow fibers are formed.

In a fast muscle, its fast nerve activity keeps this same transcription factor (NFAT) from entering the nucleus. The result? Slow muscle fibers aren't formed and the fast muscle can keep making more fast muscle fibers. That's good because fast muscles can produce more force, and they're thought to grow larger than slow muscles.

In essence, the Chin et al study demonstrated why slow nerves and slow muscles go together, and why fast nerves and fast muscles go together (their nerve activity is correlated with their specific muscle fiber formation). But as a philosopher, trainer, and lifter, I want to know what I can do with this information to build bigger, stronger muscles.

And this, my friends, is where I take an enormous leap of faith.

You see, I preach the importance of fast muscle contractions for a variety of reasons. One of the reasons is because of a study by Desmedt and Godaux. They demonstrated that fast muscle contractions activated motor units earlier; and fast contractions activated approximately three times as many motor units as slow contractions.(4) But I'm also taking what I learned from the previous studies and apply it to strength and hypertrophy training.

Here's What I'm Hoping the Future Will Show: Fast muscle actions cause more fast muscle fibers to be formed by blocking slow muscle fiber formation in the nucleus, thus allowing us quicker strength and muscle gains.

Early Intermission

Up to this point, I attempted to explain what happens when you switch nerves and muscles. And I touched on what type of muscle proteins are formed in response to slow or fast nerve activity. Those are direct correlations between nerve and muscle.

This next section, however, touches on the relationship between strength gains that occur in muscles that aren't even stimulated by their associated nerves. In other words, if you really want to see some amazing demonstrations for the power of your brain, the power of your neighboring muscles, and the power of your central nervous system, keep reading.

2. Our Brain Makes our Muscles Stronger — My all-time favorite neuroscience study was performed by Yue and Cole in 1992. I carry this study around with me like Ben Affleck must carry around his Oscar from Good Will Hunting. When I'm feeling hungry or lonely, I suckle on the page corners like a newborn pig suckles on his mama's tit. And once while in a state of inebriation, I put a wig on it and... .okay, I better stop there.

What's so mesmerizing, alluring, and radical about the Yue and Cole study? Well, they had two groups of people "perform" a strength training protocol. The first group trained their left hand muscles for 5 sessions per week for four weeks. Like any reputable study on strength enhancement, the movement had to be isolated and simple to eliminate other complex variables that occur with larger motor tasks. Basically, they abducted their left pinky finger against resistance.

Powerful pinky!

The other group? They imagined doing the same movement with the same effort and frequency. Yes, you read that right: they simply thought about the exercise, but didn't move a muscle. And just to make sure that they didn't move a muscle, the researchers hooked them up to an EMG to make sure they weren't producing any force whatsoever.

Now, for the shocking part: At the end of the study, the group that actually performed the contractions against resistance increased their strength by 30%. But the "imagined contraction" group increased their strength by 22%! (5)

I still get chills when I think about what that study demonstrates.

This is about as close to a holy grail as a neurophysiologist like me will ever find. I mean, think about that protocol and its implications. It means that we can significantly improve our strength without even contracting our muscles!

How does this happen? We really don't know. Remember what I said in the beginning, there's so much we don't know about even the most common neural tasks such as storing and recalling memories. But it's likely that by thinking about a specific movement, we're priming our descending pathways so our muscles at the end of the pathway will receive more stimulation (greater motor unit recruitment) once we actually perform the movement.

Then again, the adaptation could be limited to our higher brain centers. A committee of brain areas work together before sending a signal down your spinal cord and out to your muscles. That "committee" might get stronger when we think about a movement on a regular basis. We really don't know, but we know that our mind can improve our strength.

How To Apply This Information: It probably goes without saying, but you should make an effort to think... I mean, really think through the lifts you're trying to improve the most. When you're not in the gym, think about your squat, deadlift, bench press, and clean and jerk form. Think about the form for whatever movements you need to improve the most. And I'd be willing to take another leap of faith and say that by imagining your movements outside of the gym in a quiet room, it might help you add mass.

Want bigger calves? Train them hard, fast, and heavy in the gym. And when you're not in the gym, take time during the day to really concentrate on the calf movements you perform. With your mind focused, feel the burn in your calves, imagine the load on your calves, and picture your calves growing. The greatest bodybuilders and trainers often point to the power of the mind for building bigger, stronger muscles. These imagined contractions could very well be one of the keys. I believe that such imagined contractions will augment your results in the gym.

3. You Can Get Significantly Stronger without Getting Bigger — We all want to be big and strong. Some of us are genetically blessed with lots of muscle mass, and others (including this writer) must cuss, scream, and bleed their way to every ounce of new muscle. But one thing's for certain: we all know we can get much stronger without getting bigger. And this is an important key to understanding the nervous system.

One of the top neuroscientists in the field of motor unit recruitment and strength adaptations is Dr. Roger Enoka. Here's what he had to say about the relationship between strength and muscle size:

"Although the maximal force which a muscle can exert is directly related to its cross-sectional area, there is a poor correlation between increases in strength and muscle size." (6)

Here's how I translate what he said: If you take two, untrained 25 year-old males and test their maximal strength, it's likely that the guy who has naturally bigger quadriceps will be able to produce more force in a leg extension test. But if you compare the size of the quadriceps between two, highly-trained 25 year-old males, their size won't determine who's stronger.

That's because strength is a complex entity that's affected by neural, mechanical and muscular factors. In other words, out of the three factors that can increase strength, only one is dependent on hypertrophy, and even that's debatable. It appears you can augment muscular factors that increase strength but aren't necessarily dependent on hypertrophy. What I'm referring to are proteins that attach your contractile proteins to the Z-disc of your muscle's sarcomere.

How to Apply this Information: My position is that you should always strive to improve your performance in the gym. If you're not providing a new, challenging stress by attempting to add more weight, lift faster, and/or increase the training volume, you won't build bigger and stronger muscles.

Training for maximal strength is a great way to add more muscle, but you must provide your muscles with enough training volume to elicit a hypertrophy response. After all, that's why I mentioned that there's a poor correlation between size and strength. In my view, the studies that didn't show a correlation between the two simply didn't use a high enough training volume, intensity, or frequency.

Merely getting stronger will not make you bigger. If you're training to get stronger, but you're not getting bigger, you need to eat more calories, increase your training frequency, and/or increase your training volume. I've compiled the guidelines for sufficient training volumes in my Set-Rep Bible article.

4. We Have Brakes on our Muscles — After studying the nervous system's role in human strength and performance, I've come to this conclusion: Our nervous system has the brakes set on our muscles' capabilities. Think of a high-performance sports car: if the emergency brake is partially on, it won't be able to perform at its maximum potential. The same is true with your nervous system's control over your muscles.

Why is this so? The answer is undoubtedly more complex than any team of neuroscientists could ever uncover, but the simplest answer is probably because of protective mechanisms. Our body doesn't want to be damaged or hurt in any way, shape or form. That's why we can't help but squint and flinch when an unexpected object comes flying at our precious eyeballs. And that's why we damn near piss ourselves when someone unleashes an air horn behind us while we're reading a book. Both of those actions mimic life-threatening situations that our ancestors had to survive — actions such as dodging an oncoming raptor or running from the vicious roar of a hungry beast.

In other words, we have thousands of year's worth of survival reflex mechanisms hard-wired into our nervous system. Building bigger biceps wasn't important for survival, and neither was squatting triple your body weight. So what we must do is find ways to release the brake that our nervous system is putting on our muscles. If we do, we can tap into motor units and contractile proteins that will accelerate our size and strength beyond belief. But this "unbraking" must be gradually systematic — if it's not, we'll tear our muscles and joints to shreds.

Case in point: If your son, daughter, or mistress was trapped underneath your car, you could immediately release this brake that I'm referring to. Yep, you could probably lift up the back end of the car even though you couldn't ordinarily deadlift 600 pounds. Your brain is the commander of your nervous system, and if your brain decides that you must deadlift 600 pounds of Chevrolet to untrap your daughter, you'll be able to do it. (It's likely, however, that your lower back will remind you over the course of 3 months while you're in physical therapy.) So as I said, we must release the brake slowly.

How to Apply This Information: The first step is to find whatever motivates you to build a bigger, stronger body and constantly remind yourself of whatever it is. Studies have demonstrated that motivation causes people to immediately increase their maximal strength.(7) In other words, being motivated will help release the brake.

The next steps take place in the gym. There are two techniques that work well to ease the brake off your muscles by tricking your nervous system. The first, and one that I've discussed many times, is the supramaximal hold that causes postactivation potentiation. Check out my Primed For Muscle article for more information.

The second option, heavy 1/4 reps, works through a similar neural mechanism. This is as simple as it sounds: lift the heaviest load you can handle for the strongest 1/4 of any movement. Keep in mind, the 1/4 portion that's naturally strongest will differ depending on what movement you're performing. Examples are the last 1/4 before lockout for the squat, deadlift, military press, dip, and bench press. For exercises such as curls, pull-ups and rows, you'll only be moving the load through the first 1/4 of flexion.

The advantage of 1/4 reps is that they allow massive loads that force your nervous system to recruit more motor units. However, no bragging rights will ever be won by doing heavy 1/4 reps for every workout. Limit 1/4 reps to one workout each week. Here's a total body routine that works great to help release the brake on your muscles.

Sets: 3

Reps: 3 reps for 1/4 of the movement

Load: The heaviest weight you can handle

Rest: 90s between movement pairings (A1, rest 90s, A2, rest 90s, A1, rest 90s, A2, etc.)

A1. 1/4 Squat

A2. 1/4 Leg Curl

B1. 1/4 Dip

B2. 1/4 Chin-up

C1. 1/4 Seated Military Press

C2. 1/4 Incline Hammer Curl

D1. 1/4 Standing Calf Raise

D2. 1/4 Romanian Deadlift

Conclusion

That's it for now. I encourage you to read through this article a few times and really think about how the nervous system controls your muscles. If you open up your mind a little and think about the studies I referenced, you'll develop a greater appreciation for the elusive nervous system and all its wonders.

1. Buller AJ, Eccles JC, Eccles RM. J Physiol (Lond) 150:419, 1960.

2. Salmons S, Sreter FA. Nature 263:30-34, 1976.

3. Chin et al. Genes Dev12:2499-2509, 1998.

4. Desmedt JE, Godaux E. J Physiol 264:673-693, 1977.

5. Yue G, Cole KJ. J Neurophysiol 67(5):1114-1123, 1992.

6. Enoka R. Sports Med6:146-168, 1988.

7. Bigland-Ritchie B. Clinics in Chest Medicine 5:21-34, 1984.

November 2003

Strength in Practice By Rhonda Kotarinos, PT

Urinary incontinence is one of the most common health problems affecting women in America. It is estimated that 30% to 50% of community-dwelling older women experience urinary incontinence.1,2 In women age 18 and older, the prevalence of incontinence is estimated to be 8.5% to 47%.3 Treatment options to be considered for managing urinary incontinence should initially be the least invasive, with the fewest possible adverse complications, and should be individualized for the patient.4 This specifically refers to behavioral techniques for treating urinary incontinence.

Behavioral techniques include assisted toileting, bladder retraining, and pelvic floor muscle rehabilitation, which includes pelvic muscle exercise, biofeedback, and pelvic floor electrical stimulation. Randomized controlled trials of behavioral management have indicated that stress and/or urge incontinent episodes can be reduced by 50% to 80% through these methods of therapy.5-8

For physical therapists, behavioral management of urinary incontinence can be divided into two approaches: pelvic floor and musculoskeletal management (see Figures 1 and 2, pages 38 and 39).

Pelvic Floor Management

The pelvic floor algorithm for behavioral management is self-explanatory. It is understood that a thorough history should be taken, followed by a thorough evaluation. Evaluation of the pelvic floor is extremely important. Simplified, the physical therapist needs to determine if the patient can actively contract the pelvic floor. Once this is determined, the therapist can then develop the appropriate treatment plan.

If there is an adequate isolated active contraction, the therapist has several treatment options, which will depend on the strength of the isolated active contraction. If the pelvic floor contraction is of a trace or poor grade, the therapist may utilize facilitation, active assistive exercise, overflow, or biofeedback.

Neurophysio-logical facilitation techniques that could be used include quick stretch, tapping, and/or proprioceptive neuromuscular facilitation (PNF).

Resistance to the PNF diagonal of extension, adduction, and external rotation neurophysiologically facilitates a pelvic floor contraction. To see this normal function in action, look at the local playground where children can be seen standing with their legs crossed at the ankles in an isometric contraction of extension, adduction, and external rotation in hopes of getting the pelvic floor to send a stronger signal to the bladder.

Physical therapists are quite familiar with the theory of therapeutic exercise. When treating a muscle that is below a fair grade of strength, they utilize positions of gravity eliminated or assisted to exercise a muscle of poor or trace strength, respectively. When the pelvic floor is strong enough, progressive resistive exercise would follow. Progressive resistive exercises would be accomplished with vaginal weights or a perineometer. Progressive strengthening could lead to performing various functional activities, such as stair climbing, laundry, and sports (ie, tennis, golf), with vaginal weights in place.

Cross transfer of training is another technique the physical therapist can use to enhance the strengthening process of a weakened pelvic floor. Hellebrandt described cross transfer of training more than 50 years ago.10 Hellebrandt demonstrated that strengthening exercises to a limb will increase the strength in the unexercised contralateral limb. Kannus et al not only found a transfer of muscle strength, but also discovered a transfer of power and endurance.11 Clinically, this means that the physical therapist can establish a progressive resistive, low repetition strengthening program for the hip girdle musculature and facilitate the strengthening of the pelvic floor. Initiating the strengthening process in this manner allows minimal isolated active contractions to develop without excessive inappropriate recruitment.

Once a minimal isolated contraction is present, biofeedback can be utilized to continue the strengthening process. When the pelvic floor strength is at a fair grade, treatment would continue with progressive strengthening exercises.

Electrical Stimulation

When there is no palpable active contraction, besides utilizing neurophysiological facilitation and cross transfer of training, the therapist may choose to treat with electrical stimulation. Electrical stimulation has been used to treat gynecologic disorders for well over 100 years.12 The mechanism of action in treating urinary incontinence is not well understood, but two mechanisms are described. When there is an intact neural pathway, electrical stimulation can neurally inhibit inappropriate detrusor contractions. This is the basis for utilizing electrical stimulation to treat urge incontinence. Brubaker et al, in a randomized blinded controlled study, found that electrical stimulation at a frequency of 20 Hz with a 2 second/4 second work rest cycle and a pulse width of 0.1 second cured detrusor instability (urge incontinence/urgency) in 49% of the subjects.13

The second mechanism, which addresses stress incontinence, involves electrical stimulation of neurally intact muscle, which can promote hypertrophy of the pelvic floor musculature. Increased pelvic floor strength is associated with decreased leakage and an increased ability to inhibit inappropriate detrusor contractions. Uncontrolled studies indicate that the improvement rate is 60%.

Physical therapists have the appropriate background to be more holistic in the behavioral management of urinary incontinence. There are several aspects of musculoskeletal dysfunction that can affect the treatment of urinary incontinence. They are postural dysfunction, abdominal dysfunction and generalized weakness, specifically pelvic girdle weakness. Facilitating pelvic floor strengthening with cross transfer of training by strengthening the pelvic girdle muscles has already been described.

Postural Dysfunction

Postural dysfunction has been considered a factor in pelvic floor dysfunction for almost 100 years. Goldthwaite describes in great detail how postural dysfunctions of a flat back and increased lordosis contribute to pelvic organ prolapse, which may be a factor in urinary incontinence. Goldthwaite states that “the physician has a higher function than the mere treatment of local conditions . . . . It means at once that our work must be judged upon the basis of the ultimate cure of general efficiency rather than simply the immediate relief of some local lesion. It means that in the treatment of disturbances or displacements of the pelvic organs, it is only half doing the work if the condition is simply treated locally, while an imperfect posture which may have been largely responsible for the trouble is allowed to go uncorrected.”15

In a retrospective case-control study, Lind et al found that thoracic kyphosis was associated with uterine prolapse.16 An individualized postural corrective exercise program should be developed to address the postural dysfunction noted on evaluation.

The basic tenet of the physical therapy approach to behavioral management of urinary incontinence is to improve the function of the pelvic floor through strengthening or decreasing the tone of the pelvic floor. As already described, this can include pelvic floor exercises, biofeedback, and electrical stimulation.

Other Musculoskeletal Dysfunctions

Why do only 25% to 50% of the conservatively managed patients achieve near dryness? 5-8 There are two musculoskeletal dysfunctions that can significantly impact the pelvic floor that are frequently overlooked and not treated by many health care practitioners. They are diastasis recti and the contracture of the pelvic floor. Diastasis recti is a separation of the rectus abdominis muscles at the linea alba. A weakened abdominal wall with or without a diastasis recti is an important factor in pelvic organ support. Historically, this has been referred to as the retentive power of the abdomen wall.17 Abdominal wall strength must be maintained for it to function properly in supporting the abdominal and pelvic organs. If a diastasis is present, it must be corrected before progressive abdominal strengthening is initiated. More recent research also shows that addressing the abdominal wall facilitates pelvic floor muscle coordination, support, strength, and endurance.18

The gold standard of pelvic floor exercise to treat incontinence is a Kegel or concentric exercise of the pelvic floor. Unfortunately, this may not be the most appropriate exercise for all patients with incontinence. Optimal skeletal muscle function is dependent on a length-tension relationship. The force of a muscle contraction decreases if the muscle is too long or too short.19

The goal of therapy in treating hypertonic muscles is to decrease the excessive electrical activity that is holding the pelvic floor in a shortened state. Hypertonic pelvic floor muscles can develop through protective guarding with pain or with constant recruitment to inhibit urge. In time, the elevated EMG activity will stop, leaving the pelvic floor in a new shortened position.20 In this shortened state, the pelvic floor is no longer at its optimal length-tension relationship to adequately function to inhibit urge with resulting urge incontinence, urgency-frequency syndrome, or interstitial cystitis. The shortened pelvic floor can also be a factor in stress incontinence if it cannot reflexively contract and compress the urethra when there is increased intra-abdominal pressure.

Management of the shortened pelvic floor is multifactoral. Trigger points that may be present need to be released with or without injections. Stretching is appropriate to manage trigger points as well as contractures.

Lengthening a shortened muscle is the initiation of a strengthening program. Proprioceptive neuromuscular facilitation can be utilized to assist in lengthening the shortened pelvic floor through neurological inhibition. As the pelvic floor lengthens, the patient’s proprioception improves and the patient can actively lengthen their pelvic floor from a resting position. Because of tissue memory, it may be prudent for patients who have had pelvic floor contractures to precede their concentric (Kegel) contraction with a lengthening contraction. Success rates of behavioral approaches to incontinence might improve if physical therapists consider addressing diastasis recti and pelvic floor contracture. Much more research is needed to prove that either of these two conditions has an impact on the management of urinary incontinence. Physical therapists must be made aware at least of the possibility that the association exists so that they can begin to consider the conditions in their treatment plans.

Rhonda Kotarinos, PT, is president of Rhonda Kotarinos Ltd, Oak Brook Terrace, Ill.

References

Diokno A, Brock B, Brown M, Herzog AR. Prevalence of urinary incontinence and other urological symptoms in the non-institutionalized elderly. J Urol.1986;136:1022-5.

Thom D. Variation in estimates of urinary incontinence prevalence in the community: effects of differences in definition, population characteristics and study type. J Am Geriatr Soc. 1998;46:473-80.

Herzog AR, Fultz NH. Prevalence and incidence of urinary incontinence in community-dwelling populations. J Am Geriatr Soc. 1990;38:273-81.

Clinical Practice Guideline: Urinary Incontinence in Adults: Acute and Chronic Management. Rockville, Md: US Department of Health and Human Services, Public Health Service; 1996. Agency for Health Care Policy and Research No. 96 - 0682.

Burgio KL, Locher JL, Goode PS, et al. Behavioral vs drug treatment for urge urinary incontinence in elder women: a randomized controlled trial. JAMA. 1998;280:1985-2000.

Fantl JA, Wyman JF, McClish DK, Harkins SW, Elswick RK, Taylor JR. Efficacy of bladder training in older women with urinary incontinence. JAMA. 1991;265:609-13.

Largo-Janssen TL, Debruyne PM, Smits AJ, van Weil C. Controlled trial of pelvic floor exercises in the treatment of urinary stress incontinence in general practice. Br J Gen Pract. 1991;41:445-449.

Subak LL, Quesenberry CP, Posner SF, Cattolica E, Soghikian K. The effect of behavioral therapy on urinary incontinence: a randomized controlled trial. Obstet Gynecol. 2002;100:72-78.

Knott M, Voss DE. Proprioceptive Neuromuscular Facilitation. New York: Harper & Row; 1968.

Hellebrandt FA. Cross education: ipsilateral and contralateral effects of unilateral training. J Appl Physiology. 1951;4:136.

Kannus P, Alosa D, Cook L, et al. Effects of one-legged exercise on strength, power and endurance using isometric and concentric isokinetic training. Eur J Appl Physiol. 1992;64:117-126.

Massey GB. Conservative Gynecology and Electo-Therapeutics. Philadelphia: F.A. Davis Company; 1889.

Brubaker LT, Benson JT, Bent A, Clark A, Shott S. Transvaginal electrical stimulation for female urinary incontinence. Am J Obstet Gynecol. 1997;177:536-540.

Fall M, Lindstrom S. Electrical stimulation: a physiological approach to the treatment of urinary incontinence. Urol Clin North Am. 1991;18:383-407.

Goldthwaite JE. The relation of posture to human efficiency and the influence of poise upon the support and function of the viscera. Boston Medical and Surgical Journal. 1909;161:839-848.

Lind LR, Lucente V, Kohn N. Thoracic kyphosis and the prevalence of advanced uterine prolapse. Obstet Gynecol. 1996;87:605-9.

Penrose CB. Textbook of Diseases of Women. Philadelphia: WB Saunders; 1907.

Sapsford RR, Hodges PW. Contraction of the pelvic floor during abdominal maneuvers. Arch Phys Med Rehabil. 2001;82:1081-88.

Jones DA, Round JM. Skeletal Muscle in Health and Disease. Manchester, England: Manchester University Press; 1990:21.

Exploratory and analytical survey of therapeutic exercise. Northwestern University Special Therapeutic Exercise Project. Am J Phys Med. 1967;46:1-1135.

Unilateral arm strength training improves contralateral peak force and rate of force development Journal European Journal of Applied Physiology

ISSN 1439-6319 (Print) 1439-6327 (Online)Issue Volume 103, Number 5 / July, 2008

Pages 553-559SpringerLink Date Tuesday, April 29, 2008

Michael Adamson1, Niall MacQuaide1, Jan Helgerud2, 3, Jan Hoff2, 4 and Ole Johan Kemi1, 2 (1) Institute of Biomedical and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK

(2) Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway

(3) Hokksund Medical Rehabilitation Center, Hokksund, Norway

(4) Department of Physical Medicine and Rehabilitation, St Olavs Hospital, Trondheim, Norway

Accepted: 16 April 2008 Published online: 29 April 2008

Abstract

Neural adaptation following maximal strength training improves the ability to rapidly develop force. Unilateral strength training also leads to contralateral strength improvement, due to cross-over effects. However, adaptations in the rate of force development and peak force in the contralateral untrained arm after one-arm training have not been determined. Therefore, we aimed to detect contralateral effects of unilateral maximal strength training on rate of force development and peak force. Ten adult females enrolled in a 2-month strength training program focusing of maximal mobilization of force against near-maximal load in one arm, by attempting to move the given load as fast as possible. The other arm remained untrained. The training program did not induce any observable hypertrophy of any arms, as measured by anthropometry. Nevertheless, rate of force development improved in the trained arm during contractions against both submaximal and maximal loads by 40–60%. The untrained arm also improved rate of force development by the same magnitude. Peak force only improved during a maximal isometric contraction by 37% in the trained arm and 35% in the untrained arm. One repetition maximum improved by 79% in the trained arm and 9% in the untrained arm. Therefore, one-arm maximal strength training focusing on maximal mobilization of force increased rapid force development and one repetition maximal strength in the contralateral untrained arm. This suggests an increased central drive that also crosses over to the contralateral side.

Training With Unilateral Resistance Exercise Increases Contralateral Strength

Munn J, Herbert RD, Hancock MJ

J Appl Physiol

vol. 99, 1880 - 1884, 2005

Abstract

Background: A recent meta-analysis of randomized studies found that unilateral training produces a small but statistically significant effect on the strength of the homologous muscles on the contralateral side. However, the studies included in the meta-analysis have several limitations. No consensus exists on the mechanism that produces contralateral strength adaptations, but the magnitude of strength gained on the contralateral side has been suggested to relate to the strength gain on the trained side. The objective of this study was to investigate factors that affect increases in strength of an untrained limb when the contralateral limb is trained.

Methods: Subjects were randomly assigned to a control group of 1 of 4 training groups that performed supervised elbow flexion contractions: 1 set at high speed, 1 set at low speed, 3 sets at high speed, or 3 sets at low speed. Training was conducted 3 times per week for 6 weeks, with a 6- to 8-repetition maximal load. A group of control subjects attended these sessions but did not exercise. Elbow flexor strength was measured with a 1-repetition maximum arm curl before and after training.

Results: Training with 1 set at slow speed did not provide an increase in contralateral strength. However, training with 3 sets increased strength of the untrained arm by a mean of 7% of initial strength. Training with fast contractions tended to produce a greater increase in contralateral strength than that attained with slow training (Table 1). However, the number of sets and training speed did not show any interaction.

Conclusions: Three sets of progressive dynamic resistance exercise produced small contralateral increases in strength, which are graded according to the increases in ipsilateral strength. However, whether this small increase in contralateral strength is functionally important has not been determined.

Original Article

Unilateral nerve injury produces bilateral loss of distal innervation

Anne Louise Oaklander, MD, PhD^*, Jennifer M. Brown, BS

Nerve Injury Unit, Departments of Anesthesiology, Neurology, and Neuropathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA

email: Anne Louise Oaklander (aoaklander@partners.org)

^*Correspondence to Anne Louise Oaklander, Massachusetts General Hospital, 55 Fruit Street, Clinics 3, Boston, MA 02114

Funded by:
NIH, NINDS; Grant Number: R01NS42866
Paul Beeson Scholarship from the American Federation for Aging Research

Abstract

There are no known anatomical connections between neurons that innervate homologous right and left body parts. Nevertheless, some patients develop bilateral abnormalities after unilateral injury, a phenomenon often unrecognized and not yet characterized. Therefore, we examined in rats the effects of ligating and cutting one tibial nerve on sensory function and on density of innervation in hind paws contralaterally as well as ipsilaterally to the injury, at times between 1 day and 5 months after surgery. Punches removed from tibial- or sural-innervated planter paw skin were immunolabeled to quantitate epidermal nerve endings. Naive and sham-operated rats provided controls. Axotomized rats had near-total loss of PGP9.5⁺ innervation within ipsilateral tibial-innervated skin at all time-points. Adjacent ipsilateral sural-innervated skin had persistent hyperalgesia without denervation, and robust axonal sprouting at 5 months after surgery. Contralesional hind paws lost 54% of innervation in tibial-innervated epidermis starting 1 week after surgery and persisting throughout. Contralesional sural-innervated skin had neither neurite loss nor sprouting. These results imply that unilateral nerve injury can cause profound, long lasting, nerve-branch-specific loss of distal innervation contralaterally as well as ipsilaterally. They discredit the practice of using tissues contralateral to an injury to provide normative controls and suggest the possibility of rapid, transmedian postinjury signals between homologous mirror-image neurons.

Pain produces mystery nerve loss: Mirror-image pain distresses researchers

By William J. Cromie
Harvard News Office

People who injure an arm or leg sometimes develop pain, swelling, or other unexpected symptoms in the opposite, uninjured arm or leg. Medical reports of such mirror-image effects go back at least to the Civil War and usually are blamed on overuse of the undamaged arm or leg.

Anne Louise Oaklander, director of the Nerve Injury Unit at Massachusetts General Hospital in Boston, saw the glimmering of another explanation while studying patients with nerve damage from shingles. Caused by the virus that produces chicken pox in children, shingles inflicts adults with a painful rash of crusting blisters. It usually occurs on one side of the body. When the rash is treated, the pain goes away for some people, but lingers in others.

Oaklander, who is also an assistant professor of anesthesiology and neurology at Harvard Medical School, removed pinhead-size skin samples that allowed her to count how many nerves are working in small areas of skin. She found dramatic, long-lasting loss of nerve endings in areas previously affected by shingles. That was expected. But when her team checked skin from unaffected areas directly opposite the shingles outbreak, they were startled to see half the nerve endings had been lost there as well.

What is more, the greater the loss of nerves on the unaffected side, the more pain patients felt on the side previously affected with shingles.

Other researchers assumed that the mirror-image damage was due to spread of the virus, which didn't cause a rash on the other side. But Oaklander and other researchers had found similar mirror-image effects in humans and lab animals who had suffered direct injuries where no viruses were involved. So she decided to investigate further.

Searching for missing nerves

Oaklander and her collaborators carefully cut a branch of the sciatic nerve on one hind paw of a bunch of lab rats. This killed all nerve endings in the cut area. But a few weeks after the surgery they also found that, in the precise spot on the opposite paw, nerves had also died. "That was completely unprecedented," Oaklander comments.

More than half (54 percent) of the nerves died in the same spot on the uninjured limb, a major loss. After five months, a big part of the 2-year life span of rats, no regrowth of those nerve endings occurred.

Oaklander and her student assistant, Jennifer Brown, describe details of these experiments in the May issue of the Annals of Neurology.

Oaklander also has observed this crossover effect in patients with problems other than shingles. "You see it in all kinds of injuries - cut fingers, sprained ankles, broken legs," she notes. "We intend to investigate this effect in a more systematic way, and hope that our work will prompt other researchers to do the same. If further investigation reveals now unknown connections between opposite sides of the body, it will have important implications for surgeons, orthopedists, and others involved in treatment and rehabilitation of one-sided injuries."

Oaklander says of her finding, "For starters, it implies that matching areas on two sides of the body communicate with each other in ways that no one was aware of until now. There are no known pathways connecting matching sensory nerves on opposite sides of the body."

Changing the textbooks

What could this mean for the study of anatomy? "For starters, it implies that matching areas on two sides of the body communicate with each other in ways that no one was aware of until now," Oaklander answers. "There are no known pathways connecting matching sensory nerves on opposite sides of the body." If such pathways are found by further investigation, changes will have to be made in a lot of textbooks.

Another implication concerns the experiments of researchers around the world who take sides to study the effects of injury or disease. They compare what happens on the diseased or injured side to the mirror-image side, which they believe is normal. "Now, these scientists will have to use other sources for these important comparisons, such as uninjured humans or animals," Oaklander points out.

Why wasn't crossover damage found before? "Because scientists and doctors never looked for it," Oaklander answers. "It doesn't fit in with our current understanding of how the body works. You don't see it because you don't look for it."

Right now, doctors can't treat, or lessen, symptoms on the uninjured side because they don't understand what is happening. In this way, crossover pain is like phantom pain, the stabbing, burning sensation people feel in limbs that are no longer there because of amputation. Are they connected? Oaklander doesn't know. You can't examine nerve endings in limbs no longer attached to the body.

One explanation for the yet-to-be-found connections is that they are needed for good health. "It's most likely that connections we find involved in disease and injury exist for normal coordination between both sides of the body," Oaklander says.

"Our research provides a discovery, but it doesn't give us a lot of answers about why things happen the way they do," Oaklander continues. "It does, however, tell us what questions we need to work on."

She excuses herself and heads back into her lab to start that work.

Study Finds Nerve Damage Can Affect Opposite Side Of Body

ScienceDaily (Apr. 13, 2004) — BOSTON - April 2, 2004 - Researchers from Massachusetts General Hospital (MGH) have found physical evidence of a previously unknown communication between nerves on opposite sides of the body. In the May 2004 issue of Annals of Neurology, the scientists describe how cutting a major nerve in one paw of a group of rats resulted in a significant decrease in skin nerve endings in the corresponding area of the opposite limb. The study, released on the journal's website, may have major implications for the care of patients with nerve damage and also calls into question the common practice of using tissues on the opposite side of the body as controls in scientific experiments.

"Patients with pain syndromes related to nerve damage sometimes report symptoms on the side opposite their injury as well, but those reports are usually discounted because there has been no biological framework for the phenomenon," says Anne Louise Oaklander, MD, PhD, director of the MGH Nerve Injury Unit, the report's principal author. "Our evidence means that these reports can no longer be ignored and gives us a new direction for research."

It has been known for more than 100 years that, when a nerve is cut, skin nerve endings in the area supplied by that nerve quickly disappear. This is because nerve cell bodies are actually located near the spinal cord, and nerve fibers called axons extend into the limbs. When axons are severed, downstream nerve endings are cut off from the cell body and die.

Reports of opposite-side sensory effects of injury date back to the American Civil War. However, no connections are known to exist between nerve cells supplying corresponding areas on the left and right sides. In previous research Oaklander and her colleagues examined nerve endings in patients with post-herpetic neuralgia - persistent pain in an area of skin previously affected by shingles, also called herpes zoster. Along with an almost total loss of nerve endings at the site of the shingles outbreak, they also found that almost half the nerve endings on the opposite side skin had been lost, even though patients did not report pain on that side. But since shingles is caused by the varicella zoster virus, which also causes chicken pox, there was a possibility that the damage had been caused by viral spread through the spinal cord.

In the current study, Oaklander and her co-author Jennifer Brown describe their experiment in three groups of rats - an experimental group in which the tibial branch of the sciatic nerve was cut in one hind paw and two control groups, one which had sham surgery and the other had no procedures. Within one week of injury, rats in the experimental group lost almost all skin nerve endings in the part of the paw supplied by the tibial nerve. Surprisingly, they also lost 54 percent of nerve endings in the corresponding area in the opposite paw. No changes were seen in either control group. The researchers also examined the opposite-limb-area supplied by the uncut nearby sural branch of the sciatic nerve and found no change in nerve endings.

"This loss of nerve fibers in the contralateral limb is so precise - being confined to areas innervated by the matching nerve - that the communication is likely to involve nerve cells or the supporting glial cells," says Oaklander, an assistant professor of Anesthesia and Neurology at Harvard Medical School. "We need to look into what regulates this communication and how it may be altered to help treat nerve injury and pain patients."

This study was supported by grants from the National Institutes of Health and a Paul Beeson Award from the American Federation for Aging Research.

Adapted from materials provided by Massachusetts General Hospital.

Trick mirror treatment developed

A treatment using mirrors to trick the brain into healing pain is being developed by researchers.

It is based on a theory where the brain's image of the body becomes faulty, causing pain.

Looking at a reflection of a healthy hand could help people ease symptoms of persistent pain, say the scientists.

The findings by the University of Bath and the Royal National Hospital for Rheumatic Diseases researchers appear in the journal Clinical Medicine.

The researchers asked a number of patients with the debilitating condition called complex regional pain syndrome to carry out routine exercises in front of a mirror.

More than half experienced pain relief during and after the exercise and further investigations showed that even greater improvements could be achieved if the tasks were practiced beforehand.

"By using a mirror reflection of a normal limb to convince the brain that everything is alright, we have found that we can correct this imbalance and help alleviate pain in complex regional pain syndrome," said Dr Candy McCabe who works in the University of Bath's School for Health and the Royal National Hospital for Rheumatic Diseases.

"In most cases normal awareness and experience of our limbs is often based on the predicted state rather than the actual state.

"When the two do not match we think sensations are generated to alert the body that things are not as it thought - rather like an early warning mechanism. If the discrepancy is very large then pain may be experienced, as pain is the body's ultimate warning mechanism.

"We think that this system may be responsible for a range of disorders where patients feel pain for apparently no clinical reason.

"Somehow the brain's image of the body differs from what it senses. When the patient moves their hand, foot or limb, they experience pain as a result."

The research is funded by the Arthritis Research Campaign.

Phantom Limb Pain May Be Reduced By Simple Mirror Treatment

ScienceDaily (Nov. 24, 2007) — Phantom limb pain occurs in at least 90% of limb amputees according to the research. Jack W. Tsao, M.D., D.Phil., assistant professor, Department of Neurology at the Uniformed Services University of the Health Sciences (USU) conducted a sham-controlled trial using mirror and imagery therapy in patients who have had a foot or leg amputated.

Health Sciences (USU) conducted a sham-controlled trial using mirror and imagery therapy in patients who have had a foot or leg amputated.

Twenty-two patients at Walter Reed Army Medical Center in Washington, D.C. were assigned to one of three groups: one that viewed a reflective image of themselves in a mirror (mirror group); on that viewed a covered mirror; and one that was trained in mental visualization.

Eighteen patients completed the study with six in each group, and after one month of treatment 100% of the members in the mirror group reported less phantom pain, while only 17% reported a pain decrease and 50% reported worsening pain in the covered mirror group, and 67% reported worsening pain in the mental visualization group.

The study found that mirror therapy reduced phantom limb pain in patients who had undergone amputation of the lower limbs. Such pain was not reduced by either covered mirror or mental visualization treatments. These results suggest that mirror therapy may be helpful in alleviating phantom pain in lower limbs.

The study, titled “Mirror Therapy for Phantom Limb Pain,” was published in the November 22 edition of the New England Journal of Medicine.

Adapted from materials provided by Uniformed Services University of the Health Sciences, via Newswise.

Uniformed Services University of the Health Sciences (2007, November 24). Phantom Limb Pain May Be Reduced By Simple Mirror Treatment. ScienceDaily. Retrieved October 25, 2008, from http://www.sciencedaily.com/releases/2007/11/071123195218.htm

Brain Advance Access originally published online on June 20, 2008
Brain 2008 131(8):2181-2191; doi:10.1093/brain/awn124
Phantom limb pain, cortical reorganization and the therapeutic effect of mental imagery

K. MacIver¹, D. M. Lloyd², S. Kelly¹, N. Roberts³ and T. Nurmikko¹

¹Pain Research Institute, Unit of Neuroscience, School of Clinical Sciences, Lower Lane, Liverpool, L9 7AL, ²School of Psychological Sciences, Zochonis Building, The University of Manchester, Brunswick Street, Manchester, M13 9PL and ³Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, 2 Abercromby Square, Liverpool, L69 3BX, UK

Correspondence to: Kate MacIver, Pain Research Institute, Unit of Neuroscience, School of Clinical Sciences, Lower Lane, Liverpool, L9 7AL, UK E-mail: kmaciver@liverpool.ac.uk

Using functional MRI (fMRI) we investigated 13 upper limb amputeeswith phantom limb pain (PLP) during hand and lip movement, beforeand after intensive 6-week training in mental imagery. Priorto training, activation elicited during lip purse showed evidenceof cortical reorganization of motor (M1) and somatosensory (S1)cortices, expanding from lip area to hand area, which correlatedwith pain scores. In addition, during imagined movement of thephantom hand, and executed movement of the intact hand, groupmaps demonstrated activation not only in bilateral M1 and S1hand area, but also lip area, showing a two-way process of reorganization.In healthy participants, activation during lip purse and imaginedand executed movement of the non-dominant hand was confinedto the respective cortical representation areas only. Followingtraining, patients reported a significant reduction in intensityand unpleasantness of constant pain and exacerbations, witha corresponding elimination of cortical reorganization. Posthoc analyses showed that intensity of constant pain, but notexacerbations, correlated with reduction in cortical reorganization.The results of this study add to our current understanding ofthe pathophysiology of PLP, underlining the reversibility ofneuroplastic changes in this patient population while offeringa novel, simple method of pain relief.

Key Words: functional magnetic resonance imaging; phantom limb pain; mental imagery; cortical reorganization

Abbreviations: PLP, phantom limb pain; NRS, Numerical rating scale; BOLD, blood oxygenation level-dependent; ACC, anterior cingulate cortex; SMA, supplementary motor area

Received January 16, 2008. Revised May 14, 2008. Accepted May 16, 2008.

Traditional Therapy for Joint Pain - Doing More Harm Than Good?

04.05.2008 16:16

category: HEALTH / MEDICAL > Alternative Medicine

Thousands of dollars spend on joint rehab every year; thousands of work hours lost; days, months, sometimes years of lost quality of life from painful joint injuries that never heal. Dr. Berg, DC from Alexandria VA says traditional therapy has it backwards and the approach can actually prolong or worsen the injury. He explains that there is a simple, non-invasive approach to joint pain relief and recover that is faster, safer and cost significantly less and demonstrates his point weekly in free public seminars.

Alexandria, VA May 4, 2008 -- Just because insurance pays for it, doesn't mean it's the path to full recovery. Realize that the annual cost of injury in the US is almost $600 billion a year. Seniors suffer daily, and are given drugs and joint replacements as their only hope. Some patients endure months of painful stretching and manipulation of an injured limb or joint, and never regain function and range or motion. (More facts on musculoskeletal injuries at http://www.bjiprc.umich.edu/research/quickfacts.html)

Joint pain and dysfunction should never take months to resolve, states Eric Berg, DC of Alexandria, VA, developer of the new technique called Dynamic Joint Recovery. While working on a patient with phantom leg pain (painful feeling in the part of the extremity that has been amputated), Dr. Berg discovered that by treating the nerve circuits in the opposing (uninjured) leg, the 10-year chronic phantom pain was completely eliminated. This prompted Dr. Berg to do further research and he concluded that traditional approaches have it completely backwards.

"Treating the joint that hurts can take two times longer than it should," says Dr. Berg. "That's two to three times the cost, two to three times the lost income, and two to three times the length of poor quality of life," Dr. Berg adds.

Dr. Berg's new discovery and treatment never touches the painful joint but stimulates and stretches the opposing or reciprocal side to facilitate healing. This treatment has resulted in quick, consistent results. Many of his clients see significant increases in range of motion and loss of pain within minutes, even after a single session. The entire program is just a fraction of the cost of traditional therapy.

Dr. Berg's theory is based on research by neurologist Anne Louise Oaklander, MD, PhD, of Massachusetts General Hospital who found physical evidence of communication between nerves on opposite sides of the body. In the May 2004 issue of Annals of Neurology, scientists describe how cutting a major nerve in one paw of a group of rats resulted in a significant decrease in skin nerve endings in the corresponding area of the opposite limb.

According to Dr. Berg, the flaw in the traditional therapy is caused by a lack of understanding in the links between reciprocal or opposing muscles. When one muscle contracts or turns on, the opposing muscle has to relax or turn off. In traditional therapy, when the practitioner is stretching or strengthening a tight injured muscle, nerve stretch receptors get activated and make the muscle even tighter or more painful.

Dr. Berg demonstrates his theory weekly, in his free public seminars in Northern Virginia. To date, he has trained over 1,000 doctors nationwide in his methods, who rapidly and routinely free their patients from debilitating pain and limited movement at a fraction of the time and cost of traditional therapies.

Adaptations in interlimb and intralimb coordination to asymmetrical loading in human walking . Gait & Posture , Volume 23 , Issue 4 , Pages 429 - 434 J . Haddad , R . Emmerik , S . Whittlesey , J . Hamill

The purpose of this study was to examine both the intralimb (within a limb) and interlimb (between the right and left limbs) adaptations that occur in response to a unilaterally applied leg load as subjects walked at their preferred walking speed. It was hypothesized that this adaptation would alter interlimb coordination while intralimb coordination remained invariant. Subjects (n=12) were required to walk on a treadmill at preferred walking speed. Bilateral 3-D kinematic data were collected while a load placed on the leg was increased. Gait adaptations to leg-loading were assessed through changes in coordination patterns between specific limb couplings. Continuous relative phase (CRP) was used to evaluate changes in limb coordination under each experimental load condition compared to a no load baseline condition. Both changes in magnitude of CRP (root-mean-square (RMS) analysis) as well as temporal changes in CRP across the stride cycle (cross-correlation) were assessed. Cross-Correlation values changed with load for all interlimb couplings assessed suggesting alterations in interlimb coordination across the stride cycle. CRP cross-correlation values were close to 1.0 in all the intralimb couplings examined, showing a relative invariance in intralimb coordination. Coordination changes in RMS were also observed for the interlimb couplings. RMS changes were also observed in the intralimb couplings on the loaded side. It appears that gait adaptations to a unilaterally applied leg load appear both at the intralimb and interlimb level. However, the majority of changes did appear at the interlimb level, where CRP as assessed through both cross-correlation and RMS measures changed. This study supports previous results that suggested a tighter coupling exists at the intralimb level, leaving the majority of gait adaptations to occur at the interlimb level. The observed adaptation in differences between interlimb and intralimb coordination may provide insight into gait adaptations in pathological gait.

J Physiol Volume 533, Number 2, 617-625, June 1, 2001

Interlimb co-ordination in human infant stepping

Marco Y. C. Pang and Jaynie F. Yang

Department of Physical Therapy and University Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada T6G 2G4

We held infants (aged 4-12 months) over a treadmill to study how they co-ordinated the two limbs during stepping. We disturbed one limb during the stance or swing phase and recorded the responses (muscle activity and movement) from both lower limbs. Manual disturbances were applied during the stance phase by sliding the foot backward, forcing the limb into the swing phase. Disturbances were also applied in the swing phase by manually extending the hip, interfering with the forward motion of the limb. Additional disturbances were applied to see if both limbs could perform the stance and swing phase synchronously.
When the limb was forced to initiate the swing phase on one side, the contralateral limb either prolonged its contact with the ground or quickly established ground contact. When the forward motion of the limb was interrupted in the swing phase, the swing phase was prolonged on the disturbed side and the stance phase prolonged on the contralateral side. In most cases, one leg maintained ground contact. Moreover, it was easy to elicit bilateral, simultaneous stance phase, whereas it was difficult to elicit simultaneous swing phase. In cases where swing phase in the two limbs was initiated close in time, rhythmic alternate stepping was immediately restored in the following step.
- We conclude that human infants can generate co-ordinated motor responses bilaterally in response to unilateral perturbations, well before the onset of independent walking.

Science 9 March 1979:
Vol. 203. no. 4384, pp. 1029 - 1031
DOI: 10.1126/science.424729

Science, Vol 203, Issue 4384, 1029-1031
Copyright © 1979 by American Association for the Advancement of Science

On the nature of human interlimb coordination

JA Kelso, DL Southard, and D Goodman

Movement time varies as a function of amplitude and requirements for precision, according to Fitts' law, but when subjects perform two-handed movements to targets of widely disparate difficulty they do so simultaneously. The hand moving to an "easy" target moves more slowly to accommodate its "difficult" counterpart, yet both hands reach peak velocity and acceleration synchronously. This result suggests that the brain produces simultaneity of action not by controlling each limb independently, but by organizing functional groupings of muscles that are constrained to act as a single unit.

From: http://www.danzanryu.com/interlimb.html

Safety With Firearms

Inter-Limb Interaction

Of the four Firearms Safety Rules put forth by Advanced Weapons & Tactics, we refer to Rule Three as the Golden Rule: Keep you finger off the trigger until your sights are on the target. The reason we make this a major issue, from the initiation of training, is a phenomenon called inter-limb interaction. This is a term used to describe the involuntary contraction of an individual's hand and finger muscles under stressful conditions. There are three causative factors of which shooting students need to be aware:

1. Sympathetic Squeeze Response

This can occur when the shooting hand is holding the weapon, and the non-shooting hand must be employed in some forceful or violent action. One example is a typical law enforcement situation: A suspect is taken into custody at gunpoint, apparently submits, and then violently resists when the officer attempts to search or make the physical arrest with the weapon still in hand and his/her trigger finger inside the trigger guard. many police agencies have been involved in litigation over incidents caused by this training deficiency.

2. Startle Response

This can occur when one is holding a weapon improperly and a sudden unexpected stimulus occurs. For example, if a homeowner was investigating a suspicious noise in the home while armed, he/she might be suddenly exposed to a loud scream, lights suddenly coming on, or encountering a family pet in the dark. With the finger in the trigger guard, this could easily lead to an unintended shot being fired.

3. Loss of Balance Response

This can occur any time one unexpectedly stumbles or otherwise experiences an unanticipated loss of balance. An example could be the above-mentioned homeowner investigating a suspicious noise and miscounting stair steps or placing a foot on an unseen object on the floor. In each of these situations, the response is a tensing of the hands and other muscle groups in an attempt to recover one's balance. If the finger has been allowed to rest on the trigger a unintended shot is again the likely result.

If you do not see your front sight, you do not feel the trigger with your trigger finger. The solution is as simple as it is critical Teach, Enforce, and Live Rule Three!

Keep you finger off the trigger until your sights are on the target.

Effects of graded levels of exercise on ipsilateral and contralateral post-exercise resting rectus femoris mechanomyography

MCKAY William P. S.⁽¹⁾ ; JACOBSON Perry⁽¹⁾ ; CHILIBECK Philip D.⁽²⁾ ; DAKU Brian L. F.⁽³⁾ ;

⁽¹⁾Department of Anesthesia, University of Saskatchewan, Royal University Hospital, 103 Hospital Drive, Saskatoon, SK S7N 0W8, CANADA
⁽²⁾Department Kinesiology, University of Saskatchewan, 87 Campus Drive, Saskatoon, SK S7N 5B2, CANADA
⁽³⁾Department Electrical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, CANADA

Abstract

Mechanomyography has shown that "resting" muscle is mechanically active, with greater activity after vigorous exercise. This experiment studied the post-exercise resting mechanomyography activity that results from different levels of exercise; the effects of exercise levels on the contralateral non-exercised limb; and the effects of resting muscle length on post-exercise resting mechanomyographic activity. Ten healthy volunteers had mechanomyography recordings over both mid-rectus femoris, at rest, before and after sets (1, 5, 10, 20, and 30 repetitions) of right leg extensions on an isokinetic dynamometer at 60 s^-1. Sets were performed a week apart, after only sedentary activity during the previous two hours. No definite threshold effect was shown. There was a linear correlation between mechanomyography and work done (R = 0.61, P < 0.01). There was a positive correlation of change of activity between the two thighs (R = 0.62, P < 0.01), with the non-exercised thigh demonstrating about half the activity of the exercised thigh. Finally, we observed that mechanomyographic activity was greater when rectus femoris muscle length was shorter (i.e. when the leg was extended versus flexed). We conclude that resting mechanomyography increases with increasing work and that there is a cross-over for increase in mechanomyography in the non-exercised leg, suggesting a neural mechanism. The greater mechanomyographic activity at shorter muscle lengths suggests that muscle that is less stretched could more freely oscillate, producing higher MMG amplitudes. Altered activity of the muscle spindle gamma loop or Golgi tendon apparatus may also play a role in altered activity with different muscle length.

Journal Title

European journal of applied physiology

2006, vol. 98, n^o6, pp. 566-574 [9 page(s) (article)] (26 ref.)

Contralateral Effects of Upper Extremity Proprioceptive

Neuromuscular Facilitation Patterns

MARILYN PINK, MS

Electromyography was used to determine the presence of electrical activity in the nonexercised latissimus dorsi, infraspinatus, and pectoralis major muscles while the contralateral limb underwent the proprioceptive neuromuscular facilitation pattern of flexion, abduction, external rotation with elbow straight and extension, adduction, internal rotation with elbow straight. Activity was present in all of these muscles during both components of the pattern. There was no significant difference in activity for the pectoralis major muscle during the flexor as compared to extensor component. The infraspinatus was more active during the flexor component, while the latissimus dorsi was more active during the extensor component. These results could be used in planning a treatment

program for patients who are unable to exercise one of their upper extremities and who could benefit from the contralateral effects of upper extremity proprioceptive neuromuscular facilitation patterns.

Key Words: Electromyography, Exercise testing, Physical therapy.

This paper was adapted from a presentation at the Fifty-fifth Annual Conference of the American Physical Therapy Association, Atlanta, GA, June 1979.

This article was submitted February 25,1980, and accepted January27, 1981.

Australian Conference of Science and Medicine in Sport 2002:
Sports Medicine and Science at the Extremes

Sunday 13 October - Poster Program

Effect of one-handed exercise on the strength of the contralateral hand

M. Kasbparast* Islamic Azad University Karaj-Iran

In the present research, it is tried to impress on remedy aspect of exercise in such a way that if one of the part of body like hand or foot was injured and the patient has to keep it immovable for a long time, he can prevent the weakness of injured organ of strengthen it by remedy exercise. The way of work in this research was in such away that first of all the range of power of triceps muscle in both tested hands is measured by Electronic dynamometer instrument. Then with a program and by the McQueen method, they just worked on the stronger hand during 1 5 session and then after the second measuring. The range of improvement on both hand are observed and it was proved that the power range increases (20 percent) on the hand which hadn't has any exercise. So if any person has broken organ or dislocation or any fact which limits movement in the upper and lower extremity and based on the results of the research and doing the proper program in spite of any immovement in the injured organ and appearing atrophy, they can not only prevent any atrophy of the injured organ, but also can strengthen the other organ too.

Electromyographic Activity Recorded from an Unexercised Muscle During Maximal Isometric Exercise of the Contralateral Agonists and Antagonists

KATHLEEN L. DEVINE, MS, BARNEY F. LeVEAU, PhD, and H. JOHN YACK, BS

The purpose of this study was to determine if integrated electromyographic activity recorded from an unexercised muscle during contralateral exercise was dependent upon the contralateral muscle (agonist or antagonist) being exercised and upon the position of the unexercised limb. Twenty normal subjects participated in the study. Electromyographic activity was recorded, using surface electrodes, from the right rectus femoris and the right vastus lateralis muscles during four experimental conditions. Statistical analysis revealed that 1) integrated electromyographic activity recorded from the rectus femoris muscle during contralateral, isometric exercise was not significantly influenced by the position of the unexercised knee or the exercised contralateral muscle and 2) integrated electromyographic activity recorded from the vastus lateralis muscle during contralateral, isometric exercise was significantly greater when the unexercised knee was initially positioned in 10 degrees of flexion and the contralateral agonists were exercised. Integrated electromyographic activity recorded during contralateral exercise appeared to be related to the associated movements of the unexercised limb.

Key Words: Muscle contraction, Posture, Neural transmission, Electromyography.

Cross Transfer Effects of Conditioning and Deconditioning on Muscular Strength

Author: Larry G. Shaver ^a

Affiliation:

^a Physical Education Department, State University College at Brockport, Brockport, New York

Published in: Ergonomics, Volume 18, Issue 1 January 1975 , pages 9 - 16

Abstract

The purpose of the investigation was to study the effects of inactivity periods of 1, 4, 6, and 8 weeks on the retention of recently acquired levels of muscular strength in the ipsilateral and contralateral arms. The aubject8 (80 experimental and 20 control) were right-handed mole volunteers, 18 to 22 yr. The experimental subjects participated three times weekly in a 6-week high-intensity, low-repetition strength conditioning programme. Following training, the trained subjects were randomly divided into four experimental groups and stopped training for 1,4, 6, or 8 weeks. Upon completion of the inactivity periods, a retention test was administered to both arms. The data analysis revealed that all experimental groups enhanced their isometric strength levels significantly in both arms during conditioning, thus demonstrating the phenomenon of cross-transfer of isometric strength. No significant differences were found for the control group. It was also found that all experimental groups retained a significant amount of isometric strength acquisition in both arms following the inactivity periods. No significant amount of strength was lost in the conditioned as well as the unconditioned arm despite 1 week of detraining. However, detraining of 4, 6, and 8 weeks resulted in a significant loss in both arms. Finally, no significant differences were found between the 6- and 8-week inactivity groups in the conditioned as well as the unconditioned arm.

Am J Occup Ther. ;55 (3):317-23 11723973 (P,S,G,E,B)

Cross-transfer effects in the upper extremity during an occupationally embedded exercise.

M J Nagel, M S Rice

Department of Occupational Therapy, School of Allied Health, Medical College of Ohio, 3015 Arlington Avenue, Toledo, Ohio 43614-5803, USA.

OBJECTIVE: Cross-transfer effects were investigated during an occupationally embedded task that involved learning a fine motor skill. Cross-transfer is a phenomenon that occurs when an untrained limb receives some of the same benefits in performance from unilateral training that the contralateral limb received. It was hypothesized that cross-transfer would occur after a unilateral training regime using an occupationally embedded task. METHOD: Forty-eight participants (mean age = 24.4 years) volunteered for this repeated-measures study. Participants were randomly assigned to a training or control group and were asked to complete a toy maze with their right and left hands for the pretest and posttest. Whereas participants in the control group did not train, participants in the training group completed a toy maze three times a day for 7 days with their left hands. All participants returned in 1 week to complete the posttest portion of the experiment. Dependent variables included movement time, movement units, force oscillations, and average force. RESULTS: Significant decreases in movement time and force oscillations were found for the untrained limbs (p < .0125) in the training group. No significant differences were found in movement units or average force. The improved movement time and force oscillations in the untrained limb provides evidence suggesting that cross-transfer occurred. CONCLUSION: This study indicates that with a population without impairments, cross-transfer can occur during an occupationally embedded task. This phenomenon may prove useful to the field of occupational therapy to rehabilitate immobilized extremities. Further research is needed to test this phenomenon with special populations.

Effect of one-legged exercise on the strength, power and endurance of the contralateral leg

Journal	European Journal of Applied Physiology
Publisher	Springer Berlin / Heidelberg
ISSN	1439-6319 (Print) 1439-6327 (Online)
Issue	Volume 64, Number 2 / March, 1992

P. Kannus¹, D. Alosa¹, L. Cook¹, R. J. Johnson¹, P. Renström¹, M. Pope¹, B. Beynnon¹, K. Yasuda¹, C. Nichols¹ and M. Kaplan¹

(1)	McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, University of Vermont, 05 405 Burlington, VT, USA

(2)	Tampere Research Station of Sports Medicine, Kaupinpuistonkatu 1, SF-33 500 Tampere, Finland

Accepted: 19 September 1991

Summary The purpose of this investigation was to study the effect of one-legged exercise on the strength, power and endurance of the contralateral leg. The performance of the knee extensor and flexor muscle of 20 healthy young adults (10 men and 10 women) was first tested by Cybex II+ and 340 dynamometers. Then 10 subjects were chosen at random to train using one leg three times a week for 7 weeks whilst the other 10 served as controls. During the 8th week, the tests were repeated. Both quadriceps and hamstring muscles of the trained subjects showed a cross-transfer effect from the trained limb to the untrained side. This concerned the strength and power, as well as endurance characteristics of these muscles. The average change in peak torque of the quadriceps muscle was + 19% (P<0.001) in the trained limb, + 11% (P<0.01) in the untrained limb and 0% in the control limbs. In hamstring muscles the changes were + 14% (P<0.01), + 5% and –1%, respectively. Concerning muscle endurance (work performed during the last 5 contractions in the 25-repetition test) the corresponding changes were + 15% (P<0.01), +7% (P<0.01), and –1% in quadriceps muscle, and + 17% (P<0.05), +7%, and –3% in hamstring muscles. The average strength benefit in the untrained limb was +36% (hamstring muscles) and +58% (quadriceps muscle) of that achieved in the trained limb. Untrained hamstring muscle showed better benefits in the endurance parameters than in strength or power parameters, while in the quadriceps muscle this effect was reversed. A positive relationship was observed between the changes (greater improvement in the trained limb resulted in greater improvement in the untrained limb) (hamstring muscles:r=0.83,P<0.001, quadriceps muscle:r=0.53,P<0.001). In endurance parameters, this relationship was almost linear while in the strength and power parameters the results were more in favour of a curvilinear relationship with limited benefit.

Neural Adaptations to Resistive Exercise: Mechanisms and Recommendations for Training Practices.

Review Article

Sports Medicine. 36(2):133-149, 2006. Gabriel, David A 1; Kamen, Gary 2; Frost, Gail 1

Abstract:
It is generally accepted that neural factors play an important role in muscle strength gains. This article reviews the neural adaptations in strength, with the goal of laying the foundations for practical applications in sports medicine and rehabilitation.

An increase in muscular strength without noticeable hypertrophy is the first line of evidence for neural involvement in acquisition of muscular strength. The use of surface electromyographic (SEMG) techniques reveal that strength gains in the early phase of a training regimen are associated with an increase in the amplitude of SEMG activity. This has been interpreted as an increase in neural drive, which denotes the magnitude of efferent neural output from the CNS to active muscle fibres. However, SEMG activity is a global measure of muscle activity. Underlying alterations in SEMG activity are changes in motor unit firing patterns as measured by indwelling (wire or needle) electrodes. Some studies have reported a transient increase in motor unit firing rate. Training-related increases in the rate of tension development have also been linked with an increased probability of doublet firing in individual motor units. A doublet is a very short interspike interval in a motor unit train, and usually occurs at the onset of a muscular contraction. Motor unit synchronisation is another possible mechanism for increases in muscle strength, but has yet to be definitely demonstrated.

There are several lines of evidence for central control of training-related adaptation to resistive exercise. Mental practice using imagined contractions has been shown to increase the excitability of the cortical areas involved in movement and motion planning. However, training using imagined contractions is unlikely to be as effective as physical training, and it may be more applicable to rehabilitation.

Retention of strength gains after dissipation of physiological effects demonstrates a strong practice effect. Bilateral contractions are associated with lower SEMG and strength compared with unilateral contractions of the same muscle group. SEMG magnitude is lower for eccentric contractions than for concentric contractions. However, resistive training can reverse these trends. The last line of evidence presented involves the notion that unilateral resistive exercise of a specific limb will also result in training effects in the unexercised contralateral limb (cross-transfer or cross-education). Peripheral involvement in training-related strength increases is much more uncertain. Changes in the sensory receptors (i.e. Golgi tendon organs) may lead to disinhibition and an increased expression of muscular force.

Agonist muscle activity results in limb movement in the desired direction, while antagonist activity opposes that motion. Both decreases and increases in co-activation of the antagonist have been demonstrated. A reduction in antagonist co-activation would allow increased expression of agonist muscle force, while an increase in antagonist co-activation is important for maintaining the integrity of the joint. Thus far, it is not clear what the CNS will optimise: force production or joint integrity.

The following recommendations are made by the authors based on the existing literature. Motor learning theory and imagined contractions should be incorporated into strength-training practice. Static contractions at greater muscle lengths will transfer across more joint angles. Submaximal eccentric contractions should be used when there are issues of muscle pain, detraining or limb immobilisation. The reversal of antagonists (antagonist-to-agonist) proprioceptive neuromuscular facilitation contraction pattern would be useful to increase the rate of tension development in older adults, thus serving as an important prophylactic in preventing falls. When evaluating the neural changes induced by strength training using EMG recording, antagonist EMG activity should always be measured and evaluated.

Contralateral Approach to Exercise Rehab, The

Christensen, Kim D

Early physical activity has been found to stimulate healing after injury and decrease disability, even when a patient is in pain. But exercising a recently damaged area too soon can slow the healing process, perpetuate symptoms and even cause continuing problems. The question then arises: How can I start my patient exercising when I'm not sure if they can tolerate it?

One way to provide the stimulus of early exercising to an injured area, while avoiding excessive irritation, is by using contralateral exercise. This neurological phenomenon (also called "cross education" or "cross transfer") has been identified for many years, yet rarely is used by clinicians treating acute injuries. While this procedure is particularly helpful in the treatment of shoulder and ankle injuries, it can be used successfully for many areas of the body.

Doctors, therapists and researchers have found that when a muscle performs resistance exercise, a neurological stimulus crosses the spinal cord and is received in the corresponding muscle group on the other side of the body. When done repeatedly, there is a training effect that produces an adaptation in the nervous system, probably at the level of the spinal cord.1 The best technical description of this phenomenon is "neural integration of interlimb coordination."2 As chiropractors who want to help our patients, it is a very important concept to master, since we can use it to help patients recover more rapidly from an acute injury or from chronically painful movement patterns.

Research Findings

Several studies have updated our basic knowledge of cross education by testing the concept on human volunteers and investigating-the various parameters. In the first investigation, both quadriceps muscles of each study volunteer were tested for strength, and then progressive resistance exercising was performed with the left leg only. At the end of 12 weeks, significant strength gains were measured in the unexercised right legs. Researchers found the most significant improvement and the greatest gains in strength in the group that used lengthening (eccentric) exercises.3

In a more recent study, scientists examined the changes in maximum voluntary isometric contraction (MVC) in the contralateral untrained limb during unilateral resistance training. They found that progressive unilateral resistance training significantly increased the MVC, and also the electromyographic activation in both the trained and contralateral untrained limbs. Their results suggest the mechanisms underlying cross education of muscular strength are explained primarily by the activation of central neural factors during contralateral training.4

The improvements in strength that are gained with contralateral exercising are very comprehensive, as shown by another study. Twenty healthy young adults (10 men and 10 women) were first tested for strength of their quadriceps and hamstring muscles using dynamometers. Then, 10 subjects were chosen at random to train using one leg three times a week for seven weeks, while the other 10 subjects served as controls.

During week eight, the strength tests were repeated on both groups. Both the quadriceps and the hamstring muscles of the trained subjects showed a cross-transfer effect from the trained limb to the untrained side, while there was no change noted in the control group. These researchers reported that unilateral exercising produced increases in the strength, power and endurance characteristics of the contralateral (unexercised) muscles.5

How to Use Contralateral Exercises

Start by identifying the strengthening exercises your patient needs to do for the injured area. Before beginning to exercise the area of injury, the patient should perform the desired exercises on the uninjured side. This can be done while the patient is receiving pain-reducing and anti-inflammatory modalities such as electrotherapy and cooling.

In a significant acute injury (or directly following surgery), specific exercising of only the uninjured region should continue for several days up to two weeks, depending on the extent and severity of the damage. The contralateral exercises can (and should) be done whenever an injured region is immobilized, whether casted or pinned; and also when there is too much pain or inflammation to consider direct exercising.

As the patient begins to respond and healing progresses, they should begin to perform the exercises with the injured region in a careful and controlled manner. Even at this point, the patient should start and finish each session with exercises for the uninjured side. This procedure will allow a more rapid recovery by permitting aggressive exercising without irritating or causing further damage to the injured region.

Take Advantage of Early Exercise

Start your acute-injury patients on an exercise program immediately following injury, but avoid direct exercising of the injured area initially. Recommend contralateral exercises to supply the stimulus necessary to take advantage of the early exercise phenomenon, while avoiding the potential for re-injury of the damaged area. Show the patient which exercises to do, but start the exercises on the opposite side of the body for the first several days. Make sure patients focus on the lengthening (eccentric) part of the exercise movement, in order to make rapid and consistent improvement. As they progress and the injury begins to heal, the symptomatic region can be safely exercised, as long as the "good" side is exercised first and last during each session.

An appropriate and progressive rehab exercise program should be started early in the treatment of patients with injuries. When you incorporate early rehabilitative exercises using these specific procedures, your patients will recognize you are a knowledgeable expert. They will be excited to follow your recommendations and their rapid progress will be a tremendous motivating factor. The result will be more consistent chiropractic results and patients who recognize your expertise and leadership in the field of musculoskeletal problems.

References

1. Zhou S. Chronic neural adaptations to unilateral exercise: mechanisms of cross education. Exerc Sport Sci Rev 2000;28:177-184.

2. Howard JD, Enoka RM. Maximum bilateral contractions are modified by neurally mediated interlimb effects. J Appl Physiol 1991;70:306-316.

3. Hortobagyi T, Lambert NJ, Hill JP. Greater cross education following training with muscle lengthening than shortening. Med Sci Sports Exerc 1997;29:107-112.

4. Shima N, Ishida K, Katayama K, et al. Cross education of muscular strength during unilateral resistance training and detraining. Eur J Appl Physiol 2002;86:287-294.

5. Kannus P, Elosa D, Cook L, et al. Effect of one-legged exercise on the strength, power and endurance of the contralateral leg. A randomized, controlled study using isometric and concentric isokinetic training. Eur J Appl Physiol Occup Physiol 1992;64:117-126.

Kim D. Christensen, DC, DACRB, CCSP, CSCS, directs the chiropractic rehabilitation and well ness program at PeaceHealth Hospital in Long view, Wash. He can be contacted at kchristensen@peacehealth.org. For more information, including a brief, biography, a printable version of this article and a link to previous articles, please visit Dr. Christensen's columnist page online: www.chiroweb.com/columnist/christensen.

Effect of resistance training on muscle use during exercise

L. L. Ploutz, P. A. Tesch, R. L. Biro and G. A. Dudley
Department of Biological Sciences, Ohio University, Athens 45701.

This study examined the effect of resistance training on exercise-inducedcontrast shift in magnetic resonance (MR) images. It was hypothesized thata given load could be lifted after training with less muscle showingcontrast shift, thereby suggesting less muscle was used to perform theexercise. Nine males trained the left quadriceps femoris (QF) muscle 2days/wk for 9 wk using 3-6 sets of 12 knee extensions each day. The rightQF served as a "control." Exercise-induced contrast shifts in MR imagesevoked by each of three bouts of exercise (5 sets of 10 knee extensionswith a load equal to 50, 75, and 100% of the maximum pretraining load thatcould be lifted for 5 sets of 10 repetitions) were quantified pre- andposttraining. MR image contrast shift was quantified by determining QFcross-sectional area (CSA) showing increased spin-spin relaxation time. Onerepetition maximum increased 14% in the left trained QF and 7% in the rightuntrained QF. Left QF CSA increased 5%, with no change in right QF CSA.Left QF CSA showing contrast shift was less after each bout of the exercisetest posttraining. This was also true, to a lesser extent, for the right QFat the higher two loads. The results suggest that short-term resistancetraining reduces MR image contrast shift evoked by a given effort, therebyreflecting the use of less muscle to lift the load. Because this responsewas evident in both trained and contralateral untrained muscle, neuralfactors are suggested to be responsible.

Cross Education: Possible Mechanisms for the Contralateral Effects of Unilateral Resistance Training.

Sports Medicine. 37(1):1-14, 2007. Lee, Michael; Carroll, Timothy J

Abstract:
Resistance training can be defined as the act of repeated voluntary muscle contractions against a resistance greater than those normally encountered in activities of daily living. Training of this kind is known to increase strength via adaptations in both the muscular and nervous systems. While the physiology of muscular adaptations following resistance training is well understood, the nature of neural adaptations is less clear. One piece of indirect evidence to indicate that neural adaptations accompany resistance training comes from the phenomenon of 'cross education', which describes the strength gain in the opposite, untrained limb following unilateral resistance training. Since its discovery in 1894, subsequent studies have confirmed the existence of cross education in contexts involving voluntary, imagined and electrically stimulated contractions. The cross-education effect is specific to the contralateral homologous muscle but not restricted to particular muscle groups, ages or genders. A recent meta-analysis determined that the magnitude of cross education is [almost equal or equal to]7.8% of the initial strength of the untrained limb. While many features of cross education have been established, the underlying mechanisms are unknown.

1. Spinal Manipulation to the Good Side: http://www.totalmotionrelease.citymax.com/research.htm l
2. Acupuncture to the Opposite Side: Scroll down to bottom of 830 thru page 832 http://books.google.com/books?id=iNZ9kiyPPUwC&pg=PA833&lpg=PA833&dq=opposite+side+treatment&source=web&ots=uBwavHp8-j&sig=3lur4sPd3gcTXgNhfdmIp1-1as0&hl=en&sa=X&oi=book_result&resnum=3&ct=result#PPA830,M1
3. Researchers from Massachusetts General Hospital (MGH) have found physical evidence of a previously unknown communication between nerves on opposite sides of the body. http://news.bio-medicine.org/medicine-news-2/Study-finds-nerve-damage-can-affect-opposite-side-of-body-3566-1/
http://www.sciencentral.com/articles/view.php3?type=article&article_id=218392543
4. Mirror Therapy for Phantom Limb Pain http://content.nejm.org/cgi/content/full/357/21/2206
5. Very interesting philosophy by Ed Stiles DO about tensegrity. http://www.omtsos.com/index.php?page=philosophy
6. A Barrett Dorko Article http://www.barrettdorko.com/articles/asking_why.htm

7. Treatment of Frozen Shoulder Using Chinese Medicine - to opposite side: http://www.itmonline.org/arts/frozenshoulder.htm

Phys Ther. 1979 Nov;59(11):1366-73.

Ipsilateral and contralateral effects of proprioceptive neuromuscular facilitation techniques on hip motion and electromyographic activity.

Markos PD.

The effects of two proprioceptive neuromuscular facilitation techniques on increasing the range of hip flexion during active straight leg raising were compared in 30 normal women. Subjects were randomly assigned into contract-relax, hold-relax, or control groups and were tested with the pelvis stabilized. An exercise technique was applied to the right lower extremity in two diagonal patterns while electrical activity was monitored from the contralateral rectus femoris, vastus medialis, semimembranosus, and biceps femoris muscles. Comparison of pretest and posttest measurements of the angle of straight leg raising of both lower extremities indicated that the increase in range of motion of the right lower extremity in subjects in the contract-relax group was significantly greater than that in the hold-relax and control groups. For the unexercised extremity, the increase in motion in subjects in the contract-relax group was significantly greater than that in the control group. Of the 30 subjects, 29 showed evidence of electrical activity in the contralateral limb when the right lower extremity was contracting against resistance.

Kokkonen, J., Nelson, A. G., Marcello, B., & Driscoll, N. (2007).

Stretching one leg increases the range of motion of the contralateral unstretched leg. ACSM Annual Meeting New Orleans, Presentation Number, 2044.

This study was designed to determine if passive static stretch of one leg would alter the range of motion of the contralateral unstretched leg. College students (N = 39) performed a one leg sit-and-reach test before and after four thirty-second bouts of right hamstring stretch held at the limit of toleration. The left leg was also tested before and after stretching of the right hamstring. After one week, Ss returned and repeated the right and left one leg sit-and-reach tests before and after stretching the right leg. Right hamstring stretching significantly increased the sit-and reach scores for both the right and left leg.

Implication: Stretching one leg can increase the range of motion of the contralateral unstretched leg. This has particular relevance to injury recovery on one limb.

Contralateral and long latency effects of human biceps brachii stretch reflex conditioning

Journal	Experimental Brain Research


Issue	Volume 107, Number 1 / November, 1995

Steven L. Wolf^{1, 2, 3}, Richard L. Segal^{1, 3}, Nancy D. Heter³ and Pamela A. Catlin³

(1)	Department of Anatomy and Cell Biology, Emory University School of Medicine, 30322 Atlanta, GA, USA

(2)	Center for Rehabilitation Medicine, 1441 Clifton Road, 30322 NE, Atlanta, GA, USA

(3)	Department of Rehabilitation Medicine and Division of Physical Therapy, Emory University School of Medicine, 30322 Atlanta, GA, USA

Abstract Results from previous studies on monkeys and human subjects have demonstrated that the biceps brachii spinal stretch reflex (SSR) can be operantly conditioned. The extent to which conditioning paradigms influence contralateral SSRs or longer latency responses in the same limb has not been examined. Nine subjects were given 10 training sessions to either increase or decrease the size of their biceps brachii SSR. Group changes were compared to the mean of six baseline (control) sessions. Both groups showed progressive SSR changes over the training sessions. Up-trained subjects increased their SSR responses by an average of 135.3% above baseline, with the last three sessions showing a 237.5% increase, while down-trained subjects reduced their average SSR responses by 43.4%, with a 52.7% reduction over the last three sessions. Ipsilateral longer latency responses showed average changes of 68.9% and-68.7% for up- and down-trainers, respectively. As in the case of SSRs, these responses changed progressively over sessions, with a 131.5% increase seen in the last three up-training sessions and an 82.4% reduction over the same period for down-trainers. Correlation coefficients between SSR and longer latency responses were high (R=0.90, up-trainers; R=0.87, down-trainers). Contralateral SSR and longer latency responses, measured in the absence of feedback and at least 10 min after ipsilateral conditioning, showed directional changes that were similar to the trained side, but their magnitudes were not as profound. Collectively, these data suggest that unilateral SSR conditioning affects spinal circuits controlling contralateral SSRs and influences longer latency responses.

PHYS THER
Vol. 86, No. 12, December 2006, pp. 1641-1650

Lengthening the Hamstring Muscles Without Stretching Using "Awareness Through Movement"

James Stephens, Joshua Davidson, Joseph DeRosa, Michael Kriz and Nicole Saltzman

Background and Purpose. Passive stretching is widely used toincrease muscle flexibility, but it has been shown that thisprocess does not produce long-term changes in the viscoelasticproperties of muscle as originally thought. The authors testeda method of lengthening hamstring muscles called "AwarenessThrough Movement" (ATM) that does not use passive stretching.Subjects. Thirty-three subjects who were randomly assigned toATM and control groups met the screening criteria and completedthe intervention phase of the study. Methods. The ATM groupwent through a process of learning complex active movementsdesigned to increase length in the hamstring muscles. Hamstringmuscle length was measured before and after intervention usingthe Active Knee Extension Test. Results. The ATM group gainedsignificantly more hamstring muscle length (+7.04°) comparedwith the control group (+1.15°). Discussion and Conclusions.The results suggest that muscle length can be increased througha process of active movement that does not involve stretching.Further research is needed to investigate this finding.

J. Physiol. (I959) I45, I93-203

EFFECTS OF MUSCLE STRETCH ON EXCITABILITY OF CONTRALATERAL MOTONEURONES

E. R. PERL

From the Department of Physiology, Upstate Medical Center, Syracuse 10,

New York, and the Department of Physiology, University of Utah

Collegeof Medicine, Salt Lake City 12, Utah*, U.S.A.

Sherrington (1909) showed that, in both the lengthening and shortening reactions of vastocrureus, sense organs within the muscle may initiate reflex changes in the contralateral vastocrureus; however, his experiments did not determine the receptors responsible for these reflexes. The relation between ipsilateral lengthening and contralateral contraction in the knee extensors (Phillipson's reflex) has been used to identify the muscle tendon organ as the source of the crossed effect (Mountcastle, 1956). On the other hand, there is no direct evidence that the ipsilateral and contralateral responses are evoked by the same receptor. In addition, this type of deductive analysis is made difficult by the demonstration that impulses in muscle afferent fibres produce a variety of excitability changes in contralateral motoneurones (Perl, 1958). Of particular pertinence to the reflexes mentioned above, a volley of impulses in Group I afferent fibres from a knee flexor or extensor muscle was shown to produce dual effects on motoneurones of the contralateral equivalent muscle an initial inhibition with a very brief central latency, followed by a more prominent facilitation. The inhibitory and facilitatory effects could be dissociated by varying the number of Group I fibres activated, suggesting that each effect was mediated by a different group of fibres, possibly originating from different sensory structures. The origin of Group I fibres from the two known stretch receptors of muscle, the muscle spindle and Golgi tendon organ, is clearly established (Hunt & Kuffier, 1951; Hunt, 1954). On the average, the muscle spindle and Golgi tendon organ have different thresholds to externally applied muscle tension, and in addition the Golgi tendon organ can be stimulated preferentially by muscle contraction (Matthews, 1933; Hunt & Kuffler, 1951; Hunt, 1954). Consequently it seemed possible, by means of appropriate stimulation, to study the relationship between activation of particular sense organs and the Group I induced excitability changes. If crossed effects could be attributed to activation of specific muscle stretch receptors, a more complete view of the reflexes originated by these receptors would be obtained. The experiments to be described show that the receptors which evoke the myotatic reflex inhibit the contralateral equivalent muscle, while the receptors responsible for autogenetic inhibition and other features of the inverse myotatic reflex (LaPorte & Lloyd, 1952) facilitate the contralateral equivalent muscle.

Medicine & Science in Sports & Exercise:Volume 34(5) Supplement 1May 2002p S287

A TEN WEEK STRETCHING PROGRAM INCREASES STRENGTH IN THE CONTRALATERAL MUSCLE.

[H17K FREE COMMUNICATION/POSTER MUSCLE STRENGTH TRAINING]

Nelson, A G.¹; Kokkonen, J¹; Arnall, D A. FACSM¹; Kalani, W¹; Peterson, K¹; Kenly, M¹

¹Louisiana State Univ, Baton Rouge, LA; Brigham Young Univ-Hawaii, Laie, HI; Northern Arizona Univ, Flagstaff, AZ.

It is well established that unilateral strength exercise will also improve the strength of the contralateral muscle group. This cross training phenomenom is most prevalent when the strength training program consists of eccentric exercises.

PURPOSE:

Since eccentric work also includes a significant stretching componentand long term stretching programs can also improve strength, it was questioned whether a unilateral stretching program would induced a cross trining effect in the contralateral muscle.

METHODS:

To test this, 7 males and 6 females participated in a 10 week program of right calf stretching. The right calf muscle was stretched 4 times for 30 s, with a 30 s rest between stretches, 4 days per week for the 10 weeks. Strength was measured before and after the stretching program using a one repetition maximum (1RM) unilateral standing toe raise.

RESULTS:

The 1RM results (mean kg ± s.d.) are as follows: Pre-Right = 36 ± 8; Post-Right = 46 ± 9†‡ Pre-Left = 36 ± 7; Post-Left = 40 ± 10†. Where † denotes post > pre (p < 0.05), and ‡ denotes right > left (p < 0.05).

CONCLUSION:

This indicates that 10 weeks of stretching the right calf only will significantly increase the strength of both calves. Hence, stretching can also induce a crosstraining effect. Since stretching can activate spinal reflexes, the above finding supports the hypothesis that the cross training mechanisms reside in the spinal column.

The Nervous System In Action

Michael D. Mann, Ph.D.

The crossed-extension reflex

If protection of the limb requires it to be elevated, then the rest of the body is imperiled by removal of the support the limb normally provided, unless some compensation is made. The reflex contraction of flexor muscles on one side of the body is always accompanied by contraction of the extensor muscles of the contralateral limb. This gives increased antigravity support on the contralateral side to hold the body upright and is called the crossed-extension reflex.The flexor reflex afferent fibers also synapse on interneurons that decussate (cross the midline) and terminate on contralateral extensor alpha-motoneurons. This pathway is polysynaptic and purely excitatory. In addition, there is the usual reciprocal inhibitory effect on the contralateral flexor alpha-motoneurons.

Electromyography Results of Exercise Overflow in Hemiplegic Patients

VIRGINIA M. MILLS and LEE QUINTANA

The purpose of this study was to determine the effects of exercise overflow in

hemiplegic patients. Eleven subjects with a diagnosis of cerebrovascular accident

(CVA) performed active exercises with their uninvolved extremities while their

involved extremities were monitored with EMG. The muscles monitored were the

biceps brachii, triceps brachii, and quadriceps femoris. Active exercise of the

comparable uninvolved muscles was performed under three different weight

lifting conditions: 1) maximal weight, 2) 50% of the maximal weight, and 3) no

weight. Significant (p < .05) overflow to the involved nonexercised extremities

was found in all of the exercise conditions. Overflow was frequently found in all

three muscle groups when only one muscle group was being exercised. Overflow

always occurred in the contralateral homologous muscle. Exercise overflow

appears to be an effective therapeutic technique to facilitate muscle activity in

paretic muscles. This muscle activity may cause desired or undesired muscular

effects during therapy in the rehabilitation of patients with CVAs.

This paper was presented at the Annual Conference of the Academy and Congress of Physical Medicine and Rehabilitation, Los Angeles, CA, November 1983. This article was submitted November 17, 1983; was with the authors for revision 31 weeks; and was accepted December 28, 1984.

Volume 65 / Number 7, July 1985

Muscle-specific variations in use-dependent crossed-facilitation of corticospinal pathways mediated by transcranial direct current (DC) stimulation

Richard G. Carson^a^,^,, Niamh C. Kennedy^a, Mark A. Linden^b and Lisa Britton^a

^aSchool of Psychology, Queen's University Belfast, UK ^bSchool of Nursing and Midwifery, Queen's University Belfast, UK

Neuroscience Letters
Volume 441, Issue 2, 22 August 2008, Pages 153-157 Received 4 April 2008; revised 11 June 2008; accepted 14 June 2008.

The tendency for contractions of muscles in the upper limb to give rise to increases in the excitability of corticospinal projections to the homologous muscles of the opposite limb is well known. Although the suppression of this tendency is integral to tasks of daily living, its exploitation may prove to be critical in the rehabilitation of acquired hemiplegias. Transcranial direct current (DC) stimulation induces changes in cortical excitability that outlast the period of application. We present evidence that changes in the reactivity of the corticospinal pathway induced by DC stimulation of the motor cortex interact systematically with those brought about by contraction of the muscles of the ipsilateral limb. During the application of flexion torques (up to 50% of maximum) applied at the left wrist, motor evoked potentials (MEPs) were evoked in the quiescent muscles of the right arm by magnetic stimulation of the left motor cortex (M1). The MEPs were obtained prior to and following 10 min of anodal, cathodal or sham DC stimulation of left M1. Cathodal stimulation counteracted increases in the crossed-facilitation of projections to the (right) wrist flexors that otherwise occurred as a result of repeated flexion contractions at the left wrist. In addition, cathodal stimulation markedly decreased the excitability of corticospinal projections to the wrist extensors of the right limb. Thus changes in corticospinal excitability induced by DC stimulation can be shaped (i.e. differentiated by muscle group) by focal contractions of muscles in the limb ipsilateral to the site of stimulation.

Central fatigue explains sex differences in muscle fatigue and contralateral cross-over effects of maximal contractions

Journal

Pflügers Archiv European Journal of Physiology

Peter G. Martinand Jodie Rattey

Received: 12 October 2006 Revised: 3 December 2006 Accepted: 21 December 2006 Published online: 7 March 2007

Abstract A sustained voluntary contraction increases central fatigue and produces a ‘cross-over’ of fatigue during a subsequent contraction of the contralateral limb. These studies compared the magnitude of these changes for men and women. Force and electromyographic responses from dominant (study 1; n=8 men, 8 women) or non-dominant (study 2; n=7 men, 8 women) leg extensors to nerve stimulation were recorded at rest and during brief maximal voluntary contractions (MVCs), before and after 100-s sustained MVCs performed with the dominant leg. For the dominant leg, force was reduced more for men (by 24%) than women (by 16%, P<0.05) after the sustained contractions. Similarly, voluntary activation during these contractions was reduced more for men (by 22%) than women (by 9%, P<0.05). Conversely, resting twitches changed similarly for both sexes (P>0.05). For the non-dominant leg, men experienced a reduction in force (by 13%, P<0.001) and had greater deficits in activation than women (9% vs 3%, P<0.05), after sustained contractions of the dominant leg. Therefore, sustained MVCs produce greater central fatigue and a more pronounced ‘cross-over’ of effects to the contralateral limb for men compared to women. These findings demonstrate distinct differences between sexes in the way the nervous system adapts to changes associated with fatigue.

Tohoku J. exp. Med., 1983, 141, 241-242 Short Report

How to Use Bilateral Motions in Facilitation Techniques

RYUICHI NAKAMURAan d TOMIYOSHCI HIDA

Institute of Rehabilitation Medicine, Tohoku University

School of Medicine, Narugo, Miyagi 989-68

NAKAMURA, R. and CHIDA, T. How to Use Bilateral Motions in Facilitation

Techniques. Tohoku J. exp. Med., 1983, 141(2), 241-242

Influence of contralateral finger motions on ipsilateral finger extension was analyzed in order to explore optimal condition of bilateral motions as a facilitation technique, measuring motor times (MTs) of finger extensor muscles in four conditions; homonymous or non-homonymous as for muscle coupling and simultaneous or successive as for timing of motion-initiation. Compared to unilateral motion, MTs shortened only in bilateral motion with preceding sustained contractions of the contralateral homonymous muscle.

Bilateral motions are often used in active-assistive exercises to restore the motor

function of paralysed muscles in hemiplegia (Harris 1978; Nakamura 1977). There still

remain practical questions, i.e., what kinds of muscle coupling, homonymous or nonhomonymous, and timing of movement initiation, simultaneous or successive, are more effective. This study, using reaction time (RT) experiments, analyzed the influence of contralateral finger motions on ipsilateral finger extension in order to explore optimal

condition of bilateral motions as a facilitation technique. RTs, premotor times (PMTS; latency from stimulus to EMG onset) and motor times (MTs; latency from EMG onset to actual motion) of finger extension were examined in 12 healthy right handed adults. The method of ET measurements was already reported in details (Nakamura and Taniguchi 1971). In short, EMGs of the finger extensor muscles and movements of the middle finger were recorded on a memoscope where PMT and MT were measured with a msec scale. The subjects preformed two tasks. In task 1 bilateral simultaneous motions with the homonymous or non-homonymous muscle coupling were administered, and in task 2 a sustained contraction of the contralateral homonymous or non-homonymous muscle was started with a warning signal. The order of the tasks was counterbalanced across the subjects. They were asked to extend rapidly their left or right fingers responding to a tone stimulus presented 2 sec after the warning in three conditions; without motions of the contralateral fingers (control, S), with the contralateral finger flexion (non-homonymous coupling, F), and with the contralateral finger extension (homonymous coupling, E). The half of the subjects performed the trials with the left hand and the others with the right. The three conditions were randomly assigned with each block of six trials, and four blocks of each condition were repeated. The first trial after change of the conditions was discarded and the remaining 20 trials in each condition were used for statistical analysis.

Table 1 shows the means of RTs, PMTS and MTs in tasks 1 and 2. PMTS of both

tasks were longer in F and E than in S (p<0.01). PMTS prolonged in the bilateral motions

regardless of the direction and the timing of motions. This phenomenon would be

attributed to the increased attentional demands of movement organization and execution

but not different in E, and MTs of task 2 were not different in F but short in E (p <0.01).

The shortening of MTs was obtained only in the task with preceding sustained contractions of the contralateral homonymous muscles. Coactivation of homonymous muscles of the contralateral side accompanied with unilateral motions is a common finding in healthy subjects, and its latency varies widely between 50 msec (Kristeva et al. 1979) and more than 500 msec (Hopf et al. 1974). According to Soto et al. (1974), the level of coactivation reached its maximum at 1.64 sec after the subject made a voluntary sustained contraction. These reports and the present results indicate that sustained contraction of the contralateral homonymous muscles should be executed about 2 sec before the initiation of active assistive exercises to facilitate the activity of paretic muscles.

References

1) Harris, F.A. (1978) Facilitation techniques in therapeutic exercise. In: Therapeutic

Exercise. 3rd ed., edited by J.V. Basmajian, Williams & Wilkins, Baltimore, pp.

93-137.

2) Hopf, H.C., Schlegel, H.J. & Lowitzsch, K. (1974) Irradiation of voluntary activity

to the contralateral side in movements of normal subjects and patients with central

motor disturbances. Europ. Neurol., 12, 142-147.

3) Kristeva, R., Keller, E., Deecke, L. & Kornhuber, H.H. (1979) Cerebral potentials

proceding unilateral and simultaneous bilateral finger movements. EEG din.

Neurophysiol., 47, 229-238.

4) Marteniuk, R.G. & Mackenzie, C.L. (1980) Information processing in movement

organization and execution. In: Attention and Performance. VIII, edited by R.S.

Nickerson, Lawrence Erlbaum Associates, New Jersey, pp. 29-57.

5) Nakamura, R. (1977) Physical Therapy of Disorders of Central Nervous System,

Ishiyaku Publ., Tokyo. (Japanese)

6) Nakamura, R. & Taniguchi, R. (1977) Reaction time in patients with cerebral

hemiparesis. Neuropsychology, 15, 845-848.

7) Soto, R.A., Sanz, O.P., Sica, R.E.P. & Chorny, D. (1974) Facilitation of muscle

activity by contralateral homonymous muscle action in man. Medicina, 34, 481-484.

J. Phy8iol. (1978), 277, pp. 359-366 359

BLOOD FLOW IN THE RESTING FOREARM DURING PROLONGED

CONTRALATERAL ISOMETRIC HANDGRIP AT MAXIMAL EFFORT

BY BRITA EKLUND AND LENNART KAIJSER

From the Departments of Clinical Physiology, Karolinska Hospital and

Serafimer Hospital, Stockholm, Sweden

(Received 16 August 1977)

SUMMARY

1. In earlier studies we have shown that muscle contraction performed as handgrip

at constant force, one third of maximal voluntary contraction (MVC), induces

a rapid vasodilation in the resting contralateral forearm which in all probability is

neurogenically mediated, followed by a relative increase in resistance.

2. The maintenance of contraction at one third MVC for 2 min requires continuously

increasing effort because of fatigue, as also evidence by the e.m.g. The

biphasic response of the vascular bed may then be related to the increasing intensity

of somatomotor activation which is needed to maintain contraction force, or,

alternatively, to differences in vasomotor activity on initiation of and continued

muscle activity.

3. To elucidate these two possibilities blood flow in the resting forearm was

measured during contralateral handgrips at constant maximal effort for 6 min (in

which case force will drop) and compared to handgrip at constant force, one third

MVC, for 2 min.

4. The flow reaction during prolonged contraction at maximal effort was similar

to that induced by contraction at constant force with a marked transient lowering

of vascular resistance, although maximal vasodilation tended to be more pronounced

and occur earlier.

5. The results indicate that the rapid decrease in vascular resistance is related

primarily to the initiation of somatomotor activity, whereas continued muscle contraction

produces a relative increase in vasoconstrictor activity irrespective of changes

in contraction effort.

INTRODUCTION

Intense muscle activation is accompanied by pronounced and rapidly occurring

increases in arterial pressure and heart rate, the initial phase being of neurogenic

origin (Tuttle & Horvath, 1957; Lind, Taylor, Humphreys, Kenelly & Donald, 1964;

Freyschuss, 1970; Delius, Hagbarth, Hongell & Wallin, 1972; Eklund, Kaijser &

Knutsson, 1974). Its effect on vascular resistance in a peripheral vascular bed was

analysed by Eklund et al. (1974) by measuring arterial pressure and blood flow in

the resting forearm during contralateral handgrip. Isometric handgrip at one

third of maximal voluntary contraction force (MVC) for 2 min was found to induce

an initial decrease in vascular resistance in the resting forearm, followed by a

return to precontraction level towards the end of the contraction period. The rapid

occurrence of the increase in blood flow suggested neurogenic mediation, and in

a subsequent study it was shown that to a large extent it was mediated by fiadrenergic

mechanisms, since it could be attenuated by regional fl-adrenergic blockade (Eklund & Kaijser, 1976). The gradual increase in resistance towards the end of contraction, which was found, could be abolished by regional a-adrenergic blockade. Thus it seemed to be the result of a continuous increase in a-adrenergic relative to ,8-adrenergic effects.

There are several possible interpretations of this biphasic effect on vascular resistance.

(1) It may be peripheral in origin. Contraction at constant force requires increased effort due to progressive fatigue and the continuous increase in somatomotor activation which is then developed to maintain force (Clarke, Hellon & Lind, 1958) may be paralleled by an increase in activity in sympathetic vasomotor fibres. A 'dose-response' relationship (Brungardt, Swan & Reynolds, 1974) to the effect that with moderately increased activity predominantly f8-receptors whereas with higher activity predominantly a-receptors are stimulated may then explain the biphasic effect on vascular resistance. (2) Alternatively a shift between predominant activity in anatomically distinct ,-adrenergic and ox-adrenergic fibres might occur at C.N.S. level. The shift may then be the result of increased stimulation of the vasomotor centres in parallel with the increasing somatomotor activation, produced by the increasing effort to maintain tension with fatiguing muscle fibres, or it may be related to time so that initiation of somatomotor activity is paralleled by activity in vasodilator f8-adrenergic fibres, while this activity is replaced or dominated by activity in a-adrenergic vasoconstrictor fibres as the muscle contraction is prolonged. In the present investigation the effect on blood flow in the resting forearm of a prolonged maximal voluntary isometric handgrip, where the effort was kept high and constant was compared to the effect of handgrip at constant submaximal force where the effort was continuously increasing, to elucidate whether the dual vascular response is determined mainly by the changing intensity of somatomotor activation or by different vasomotor effects of initiation and continuation of activation. To estimate semiquantitatively to what extent the flow changes occurred in skeletal

muscle oxygen saturation in the deep vein of the forearm under study was followed.

METHODS

Eight healthy male volunteers of average physical fitness were studied. Their ages ranged

between 20 and 40 years. They were carefully informed about the nature and purpose of the experiment before giving their consent to participate. For recording of arterial pressure a brachial artery was catheterized percutaneously with a teflon catheter, outer diameter 1'4 mm. The deep venous system of the resting forearm was catheterized with the same type of catheter, introduced in the distal direction and manipulated into a deep vein so that the tip could not be palpated. The distance it had been introduced, 4-8 cmn, was measured and checked again after the experiment. With the catheter in this position

the blood sampled drains mainly muscle tissue if the circulation of the hand is occluded (Coles, Cooper, Mottram & Occleshaw, 1958; Idbohrn & Wahren, 1964).

Blood flow in the resting forearm was measured by venous occlusion plethysmography with an air-filled plethysmograph (Dohn, 1956; Graf & Westersten, 1959), placed around the thickest part of the forearm. During the recording of inflow curves the circulation of the hand was occluded. Blood flow was calculated in ml. min". 100 ml-' of forearm tissue. Arterial pressure was measured by a capacitive transducer (EMT 34 or 35, Siemens-Elema). Mean pressure was obtained by electrical damping, time constant 3 sec.

Isometric contralateral handgrip was performed with a strain gauge hand-dynamometer. The force developed was displayed to the volunteer on an oscilloscope (to make it possible to maintain contraction at a predetermined force) and recorded on an ink-jet recorder (Siemens-Elema) together with e.c.g., intra-arterial pressure and plethysmographical inflow curves. The subjects were studied in the recumbent position with the resting arm at heart level. For the first part of the experiment they were instructed to maintain a handgrip contraction at maximal effort for 6 min, without activation of other muscle groups than those of the arm and without breathholding or performing a Valsalva manoeuvre. The hand with which the grip was performed rested on a pillow, the elbow slightly flexed. Arterial mean pressure and e.c.g. were recorded continuously before, during and for 3 min after the contraction. Plethysmographic

inflow curves were recorded with shortest possible intervals, for 4-6 min before, during and after the handgrip. Deep venous blood was sampled at rest, at 1, 2, 4 and 6 min of the contralateral handgrip and again 0-5, 1-5 and 3 min after the contraction. After about 45 min rest the subject performed a contralateral handgrip at constant force, one third of MVC, for 2 min. MVC was then taken to be the maximal force developed during the preceding 6 min contraction at maximal effort. Arterial mean pressure, e.c.g. and plethysmographic inflow curve were recorded as during prolonged contraction. Deep venous blood was sampled before and after contraction and at 30, 60, 90 and 120 sec of contraction.

RESULTS

Values in the text are given as mean + S.E. of mean for the group unless otherwise

stated. Significances of differences between experimental situations are calculated

from paired data. Contralateral isometric handgrip at one third of MIVC for 2 min (Fig. 1) Most subjects could maintain contraction at the predetermined force for 2 min but

in some of them force fell below that level during the last 15 sec, suggesting that 2 min

is close to the maximal time for which it is possible to keep one third of MVC with the

equipment and arm position used in the present study. The effects of contralateral isometric contraction at one third of MVC on the resting forearm blood flow, deep venous oxygen saturation, vascular resistance, arterial mean pressure and heart rate were similar to those found in previous series of experiments (Eklund et al. 1974; Eklund & Kaijser, 1976). Forearm blood flow showed a maximal increase of 127 + 25% (P < 0-01) reached at 15-75 sec of contraction, and forearm vascular resistance had decreased by 46 + 4 % at 30-60 see (P < 0.01). Deep venous oxygen saturation increased by about 16 % from 64-7 + 3-7 to 74.6 + 3.4% at 1 min (P < 0.01). Contralateral maximal isometric handgrip for 6 min (Figs. 2 and 3) The maximal force developed, after about 5 sec of contraction, was 440 + 35 N (44.5 + 3-5 kp). It decreased rapidly during the first minute to 168 + 12 N and then more slowly to level off at about 100 N. The time course of decrease in developed force was similar to that earlier described during prolonged contraction at maximal effort (Stephens & Taylor, 1972) indicating that the subjects kept the handgrip maximally. Heart rate rose rapidly to attain a maximal value at 15 see and then decreased slightly to a fairly steady level about 15 beats/min above resting level.

Arterial mean pressure increased rapidly during the first minute to remain unchanged

at about 125 mmHg from the second minute. Forearm blood flow increased significantly during the first 15 sec (P < 0 001) and reached a maximal value at 30-45 sec, the average maximal increase being 182 + 20 %.

Heart rate, arterial mean pressure, and blood flow, regional vascular resistance

and deep venous oxygen saturation in the resting forearm during contralateral handgrip

at one third of maximal voluntary contraction force for 2 min. Mean + s.E. of mean

for eight subjects. The increase in flow at 30 see tended to be greater than that produced by contraction at one third of MVC but the difference did not attain significance (0-05 < P < 0-10). The maximal increase was not significantly greater than that produced by handgrip at one third MVC. The time course, however, was different since the blood flow

decreased signficantly from 15-30 sec to 1 minI min 30 sec (P < 0.01), while it was

unchanged during that period of contraction at one-third MVC. Up to 3 min it

remained at a level significantly above the resting value, but during the rest of the

period it did not differ from that level. Forearm vascular resistance decreased

significantly during the first 15 sec (P < 0-05) and decreased further to an average

lowest value 54+4 % below the value before contraction at 30-45 sec (P < 0-01).

Developed force, heart rate and arterial mean pressure during handgrip

performed at maximal effort for 6 min. Symbols as in Fig. 1. The maximal decrease was not significantly different from that during handgrip at one third MVC. At 1-5-2 min of contraction it had returned to a value not different from that before contraction.

Deep venous oxygen saturation had increased significantly at 1 min (P < 0.01),

and decreased again to attain a level below the initial value at 4 min (P < 0.01). At

6 min it was not significantly different from the resting value.

DISCUSSION

The major finding of this study is the similarity in flow reaction (rapid increase

followed by relative decrease) produced by constant force (i.e. increasing effort) and

constant effort handgrip. Thus the biphasic response in regional vascular resistance

in the resting forearm on muscle activation seems not to be related to the intensity

ofsomatomotor activation to the effect that low grade activity induces predominantly

,8-adrenergic effects, since similar changes occurred with constant effort and increasing

effort contraction. Instead the rapid and transient flow increase at supposedly

constant degree of somatomotor activation seems to indicate that the effect on the

vascular bed is related primarily to time so that the initiation of somatomotor activity

is paralleled by activity in vasodilator 8-adrenergic fibres, which is then replaced

by or counteracted by activity in vasoconstrictor a-adrenergic fibres. Such a link

between somatomotor and vasomotor activity is probably at C.N.S. level although

the possibility of modulation on peripheral receptor level cannot be ruled out. Thus

an initial predominant activation of f-receptors might gradually be inhibited by

decreasing sensitivity to the released transmitter, unmasking a-adrenergic effects.

However, on this issue the experiment only permits speculation.

Although the maximal decrease in resistance during the first 2 min was not significantly

different between the contraction performed at one third MVC and at

maximal effort, it tended to be slightly more pronounced and the maximal change

was reached earlier during contraction at maximal effort. This may indicate that

the intensity of somatomotor activation does also have some influence on vasomotor

activation and the relation between fi- and a-adrenergic effects.

Deep venous oxygen saturation showed similar increases the first minute of both

modes of contraction, confirming that a substantial fraction of the flow increase

occurred in muscle. Like the total forearm blood flow the muscle blood flow, as

judged from the deep venous oxygen saturation, tended to decrease again earlier

during the maximal than the submaximal handgrip, but unlike the total forearm

blood flow it reached a level significantly below initial at 4 min. This would suggest

that the relative resistance increase which followed the transient decrease during

prolonged contraction was more pronounced in muscle than in skin and subcutaneous

tissue. Similarly, decreased blood flow in resting muscle has been found during steady

state dynamic leg work (Blair, Glover & Roddie, 1961) after a transient flow increase

at the onset of work (BevegArd & Shepherd, 1966). Comparing isometric and

dynamic exercise, however, it must be remembered that in the latter case muscle

tension is generally far less and hence the intensity of activity in motor neurones

lower, which in all probability means that a possible 'irradiation' to vasomotor

centres is weaker. Furthermore, in dynamic leg work where a great proportion of the

total body muscle vascular bed is subject to metabolically induced vasodilatation,

other mechanisms than in the case of isometric handgrip, to a great extent reflexogenic,

must operate to adjust the circulation.

While the initial vascular reactions on muscle activation, as discussed previously,

seem to be elicited directly by central nervous mechanisms and mediated neurogenically,

blood pressure and flow during prolonged contraction must be affected to

a great extent by reflexes from, e.g. the baroceptors and also circulating catecholamines,

released from the adrenal medulla. Blood catecholamine concentrations have

been shown to increase continuously throughout prolonged forceful handgrip, but

since heart rate and arterial mean pressure as well as forearm blood flow remained

constant from the third to the sixth min of contraction in the present study, an

influence of circulating catecholamines seems to have been of minor importance. The

levelling off of the mean arterial pressure after about 3 min of contraction could

then suggest an elevated 'set point' of the baroceptors (see Smith, 1974). The

gradual pressure increase followed by levelling off at a higher level is then compatible

with the assumption that an alteration in set point occurs rapidly at the onset of

contraction, but that the new pressure level is attained only slowly due to the competing

effect of the initial centrally mediated vasodilation. However, the exact interplay between central and peripheral effects on vasomotion during prolonged muscle contraction cannot be established by the present study.

REFERENCES

BEVEGXRD, B. S. & SHEPHERD, J. T. (1966). Reaction in man of resistance and capacity vessels in forearm and hand to leg exercise. J. apple. Phyaiol. 21, 37-46.

BLAIR, D. A., GLOVER, W. E. & RODDIE, I. C. (1961). Vasomotor response in the human arm during leg exercise. Circulation Res. 9, 264-274.

BRUNGARDT, J. M., SwAN, K. G. & REYNOLDS, D. G. (1974). Adrenergic mechanisms in canine hindlimb circulation. Cardiovasc. Re8. 8, 423-429.

CiARKE, R. S. J., HELLoN, R. F. & LIND, A. R. (1958). The duration of sustained contraction of the human forearm at different muscle temperatures. J. Phyaiol. 143, 454-473.

CouEs, D. R., COOPER, K. E., MOTrRAM, R. F. & OCCLESHAW, J. V. (1958). The source of blood samples withdrawn from deep forearm veins via catheters passed upstream from the median cubital vein. J. Physiol. 142, 323-328.

DELIUs, W., HAGBARTH, K.-E., HONGELL, A. & WALLiw, B. G. (1972). Manoeuvres affecting sympathetic outflow in human muscle nerves. Acta phy8iol. 8cand. 84, 82-94.

DOHN, K. (1956). Plethysmographs usable during functional states recording volume changes in ml per 100 ml of extremity. Rep. Steno. Ho8p. 6, 147-168.

EKLUND, B. & KAIJSER, L. (1976). Effect of regional a- and ,8-adrenergic blockade on blood flow in the resting forearm during contralateral isometric handgrip. J. Physiol. 262, 39-50.

EKLUND, B., K.AISER, L. & KNUTsSON, E. (1974). Blood flow in resting (contralateral) arm and leg during isometric contraction. J. Phypiol. 240, 111-124.

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IDBOHRN, H. & WAmRRN, J. (1964). The origin of blood withdrawn from deep forearm veins during rhythmic exercise. Acta phy8iol. 8cand. 61, 301-313.

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STEPHENs, J. A. & TAYLOR, A. (1972). Fatigue of maintained voluntary muscle contraction in man. J. Phy8iol. 220, 1-8.

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J Appl Physiol 106: 830-836, 2009. First published January 15, 2009; doi:10.1152/japplphysiol.91331.2008 8750-7587/09

Strength training the free limb attenuates strength loss during unilateral immobilization

Jonathan P. Farthing, Joel R. Krentz, and Charlene R. A. Magnus

College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Submitted 6 October 2008 ; accepted in final form 10 January 2009

The objective was to determine if strength training the freelimb during a 3-wk period of unilateral immobilization attenuatesstrength loss in the immobilized limb through cross-education.Thirty right-handed participants were assigned to three groups.One group (n = 10) wore a cast and trained the free arm (Cast-Train).A second group (n = 10) wore a cast and did not train (Cast).A third group (n = 10) received no treatment (control). Castswere applied to the nondominant (left) wrist and hand by a physician.Strength training was maximal isometric ulnar deviation (righthand) 5 days/wk. Peak torque (dynamometer), electromyography(EMG), and muscle thickness (ultrasound) were assessed in botharms before and after the intervention. Cast-Train improvedright arm strength [14.3 (SD 5.0) to 17.7 (SD 4.8) N·m;P < 0.05] with no significant muscle hypertrophy [3.73 (SD0.43) to 3.84 (SD 0.52) cm; P = 0.09]. The immobilized arm ofCast-Train did not change in strength [13.9 (SD 4.3) to 14.2(SD 4.6) N·m] or muscle thickness [3.61 (SD 0.51) to3.57 (SD 0.43) cm]. The immobilized arm of Cast decreased instrength [12.2 (SD 3.8) to 10.4 (SD 2.5) N·m; P <0.05] and muscle thickness [3.47 (SD 0.59) to 3.32 (SD 0.55)cm; P < 0.05]. Control showed no changes in the right arm[strength: 15.3 (SD 6.1) to 14.3 (SD 5.8) N·m; musclethickness: 3.57 (SD 0.68) to 3.52 (SD 0.75) cm] or left arm[strength: 14.5 (SD 5.3) to 13.7 (SD 6.1) N·m; musclethickness: 3.55 (SD 0.77) to 3.51 (SD 0.70) cm]. Agonist muscleactivation remained unchanged after the intervention for botharms [right: 302 (SD 188) to 314 (SD 176) µV; left: 261(SD 139) to 288 (SD 151) µV] with no group differences.Strength training of the free limb attenuated strength lossin the immobilized limb during unilateral immobilization. Strengthtraining may have prevented muscle atrophy in the immobilizedlimb.

J Appl Physiol 105: 70-82, 2008. First published May 1, 2008; doi:10.1152/japplphysiol.01298.2007
8750-7587/08

Contralateral muscle activity and fatigue in the human first dorsal interosseous muscle

Marijn Post,¹ Sibel Bayrak,² Daniel Kernell,¹ and Inge Zijdewind¹

¹Department of Medical Physiology, University Medical Center Groningen, Groningen, The Netherlands; and ²Department of Physiology, Hacettepe University Faculty of Medicine, Ankara, Turkey

Submitted 7 December 2007 ; accepted in final form 25 April 2008

During effortful unilateral contractions, muscle activationis not limited to the target muscles but activity is also observedin contralateral muscles. The amount of this associated activityis depressed in a fatigued muscle, even after correction forfatigue-related changes in maximal force. In the present experiments,we aimed to compare fatigue-related changes in associated activityvs. parameters that are used as markers for changes in centralnervous system (CNS) excitability. Subjects performed briefmaximal voluntary contractions (MVCs) with the index fingerin abduction direction before and after fatiguing protocols.We followed changes in MVCs, associated activity, motor-evokedpotentials (MEP; transcranial magnetic stimulation), maximalcompound muscle potentials (M waves), and superimposed twitches(double pulse) for 20 min after the fatiguing protocols. Duringthe fatiguing protocols, associated activity increased in contralateralmuscles, whereas afterwards the associated force was reducedin the fatigued muscle. This force reduction was significantlylarger than the decline in MVC. However, associated activity(force and electromyography) remained depressed for only 5–10min, whereas the MVCs stayed depressed for over 20 min. Thesedecreases were accompanied by a reduction in MEP, MVC electromyographyactivity, and voluntary activation in the fatigued muscle. Accordingto these latter markers, the decrease in CNS motor excitabilitylasted much longer than the depression in associated activity.Differential effects of fatigue on (associated) submaximal vs.maximal contractions might contribute to these differences inpostfatigue behavior. However, we cannot exclude differencesin processes that are specific to either voluntary or to associatedcontractions.

J Appl Physiol 104: 1656-1664, 2008. First published April 10, 2008; doi:10.1152/japplphysiol.01351.2007 8750-7587/08

Unilateral practice of a ballistic movement causes bilateral increases in performance and corticospinal excitability

Timothy J. Carroll,^1,2 Michael Lee,¹ Marlene Hsu,¹ and Janel Sayde¹

¹Health and Exercise Science, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, and ²School of Human Movement Studies, University of Queensland, Brisbane, Queensland, Australia

Submitted 20 December 2007 ; accepted in final form 1 April 2008

It has long been known that practicing a task with one limbcan result in performance improvements with the opposite, untrainedlimb. Hypotheses to account for cross-limb transfer of performancestate that the effect is mediated either by neural adaptationsin higher order control centers that are accessible to bothlimbs, or that there is a "spillover" of neural drive to theopposite hemisphere that results in bilateral adaptation. Herewe address these hypotheses by assessing performance and corticospinalexcitability in both hands after unilateral practice of a ballisticfinger movement. Participants (n = 9) completed 300 practicetrials of a ballistic task with the right hand, the aim of whichwas to maximize the peak abduction acceleration of the indexfinger. Practice caused a 140% improvement in right-hand performanceand an 82% improvement for the untrained left hand. There werebilateral increases in the amplitude of responses to transcranialmagnetic stimulation, but increased corticospinal excitabilitywas not correlated with improved performance. There were nosignificant changes in corticospinal excitability or task performancefor a control group that did not train (n = 9), indicating thatperformance testing for the left hand alone did not induce performanceor corticospinal effects. Although the data do not provide conclusiveevidence whether increased corticospinal excitability in theuntrained hand is causally related to the cross-transfer ofballistic performance, the finding that ballistic practice caninduce bilateral corticospinal adaptations may have importantclinical implications for movement rehabilitation.

Brain Topogr. 2007 Winter;20(2):77-88. Epub 2007 Oct 12.

Neuro-physiological adaptations associated with cross-education of strength.

Farthing JP, Borowsky R, Chilibeck PD, Binsted G, Sarty GE.

College of Kinesiology, University of Saskatchewan, 87 Campus Drive, Saskatoon, SK, Canada.

Cross-education of strength is the increase in strength of the untrained contralateral limb after unilateral training of the opposite homologous limb. We investigated central and peripheral neural adaptations associated with cross-education of strength. Twenty-three right-handed females were randomized into a unilateral training group or an imagery group. A sub-sample of eight subjects (four training, four imagery) was assessed with functional magnetic resonance imaging (fMRI) for patterns of cortical activation during exercise. Strength training was 6 weeks of maximal isometric ulnar deviation of the right arm, four times per week. Peak torque, muscle thickness (ultrasound), agonist-antagonist electromyography (EMG), and fMRI were assessed before and after training. Strength training was highly effective for increasing strength in trained (45.3%; P < 0.01) and untrained (47.1%; P < 0.01) limbs. The imagery group showed no increase in strength for either arm. Muscle thickness increased only in the trained arm of the training group (8.4%; P < 0.001). After training, there was an enlarged region of activation in contralateral sensorimotor cortex and left temporal lobe during muscle contractions with the untrained left arm (P < 0.001). Training was associated with a significantly greater change in agonist muscle EMG pooled over both limbs, compared to the imagery group (P < 0.05). These results suggest that cross-education of strength may be partly controlled by adaptations within sensorimotor cortex, consistent with previous studies of motor learning. However, this research demonstrates the involvement of temporal lobe regions that subserve semantic memory for movement, which has not been previously studied in this context. We argue that temporal lobe regions might play a significant role in the cross-education of strength.

Eur J Appl Physiol. 2008 Jul;103(5):553-9. Epub 2008 Apr 29.

Unilateral arm strength training improves contralateral peak force and rate of force development.

Adamson M, Macquaide N, Helgerud J, Hoff J, Kemi OJ.

Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.

Neural adaptation following maximal strength training improves the ability to rapidly develop force. Unilateral strength training also leads to contralateral strength improvement, due to cross-over effects. However, adaptations in the rate of force development and peak force in the contralateral untrained arm after one-arm training have not been determined. Therefore, we aimed to detect contralateral effects of unilateral maximal strength training on rate of force development and peak force. Ten adult females enrolled in a 2-month strength training program focusing of maximal mobilization of force against near-maximal load in one arm, by attempting to move the given load as fast as possible. The other arm remained untrained. The training program did not induce any observable hypertrophy of any arms, as measured by anthropometry. Nevertheless, rate of force development improved in the trained arm during contractions against both submaximal and maximal loads by 40-60%. The untrained arm also improved rate of force development by the same magnitude. Peak force only improved during a maximal isometric contraction by 37% in the trained arm and 35% in the untrained arm. One repetition maximum improved by 79% in the trained arm and 9% in the untrained arm. Therefore, one-arm maximal strength training focusing on maximal mobilization of force increased rapid force development and one repetition maximal strength in the contralateral untrained arm. This suggests an increased central drive that also crosses over to the contralateral side.

Acta Physiol Scand. 1996 Sep;158(1):77-88.

Neuromuscular adaptations during bilateral versus unilateral strength training in middle-aged and elderly men and women.

Häkkinen K, Kallinen M, Linnamo V, Pastinen UM, Newton RU, Kraemer WJ.

Department of Biology of Physical Activity, University of Jyväskylä, Finland.

Twelve middle-aged men and 12 middle-aged women in the 50-year-old age group (M50; range 44-57 years; W50; 43-57), and 12 elderly men and 12 elderly women in the 70-year-old age group (M70; 59-75; W70; 62-75) volunteered as subjects in order to examine effects of 12-week progressive heavy resistance strength training on electromyographic activity (EMG), muscle cross-sectional area (CSA) of the quadriceps femoris and maximal concentric force in a one repetition maximum (1 RM) test of the knee extensor muscles. One half of the subjects in each group performed the knee extension (and flexion) exercises only bilaterally (BIL), while another half performed the exercises only unilaterally (UNIL). None of the subject groups demonstrated statistically significant changes in any of the 1 RM values during the 2 week control period with no training (between week -2 and 0) preceding the actual experimental training. However, the 12-week training resulted in increases (P < 0.05-0.001) in 1 RM values in each group so that the average relative increase of 19 +/- 12% (P < 0.001) in bilateral 1 RM in all BIL trained subjects was greater (P < 0.05) than that of 13 +/- 8% (P < 0.001) recorded for all UNIL trained subjects. The average relative increases of 17 +/- 11% (P < 0.001) and 14 +/- 14% (P < 0.001) in unilateral 1 RM values of the right and left leg in all UNIL trained subjects were greater (P < 0.05) than those of 10 +/- 18% (P < 0.001) and 11 +/- 11% (P < 0.001) recorded for all BIL trained subjects, respectively. The relative average increase of 19 +/- 19% (P < 0.001) observed in the maximum averaged IEMG of both legs during the bilateral actions in all BIL trained subjects was greater (P < 0.05) than that of 10 +/- 17% (P < 0.05) recorded for all UNIL trained subjects. The relative increases of 14 +/- 12% (P < 0.001) and 11 +/- 6% (P < 0.001) recorded for the CSA in all BIL and UNIL trained subjects did not differ significantly from each others. The present findings suggest that progressive heavy resistance strength training leads to great increases in maximal dynamic strength of the trained subjects accompanied by both considerable neural adaptations and muscular hypertrophy not only in middle-aged but also in elderly men and women. Both bilateral and unilateral exercises are effective to produce functional and structural adaptations in the neuromuscular system, although the magnitude of functional strength increase seems to be specific to the type of exercise used, further supporting the principle of specificity in the design of strength programmes.

PMID: 8876751 [PubMed - indexed for MEDLINE]

Clin Neurophysiol. 2009 Feb 18. [Epub ahead of print]

Unilateral strength training increases voluntary activation of the opposite untrained limb.

Lee M, Gandevia SC, Carroll TJ.

Health and Exercise Science, School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, Australia.

OBJECTIVE: We investigated whether an increase in neural drive from the motor cortex contributes to the cross-limb transfer of strength that can occur after unilateral strength training. METHODS: Twitch interpolation was performed with transcranial magnetic stimulation to assess changes in strength and cortical voluntary activation in the untrained left wrist, before and after 4 weeks of unilateral strength-training involving maximal voluntary isometric wrist extension contractions (MVCs) for the right wrist (n=10, control group=10). RESULTS: Wrist extension MVC force increased in both the trained (31.5+/-18%, mean+/-SD, p<0.001) and untrained wrist (8.2+/-9.7%, p=0.02), whereas wrist abduction MVC did not change significantly. The amplitude of the superimposed twitches evoked during extension MVCs decreased by 35% (+/-20%, p<0.01), which contributed to a significant increase in voluntary activation (2.9+/-3.5%, p<0.01). Electromyographic responses to cortical and peripheral stimulation were unchanged by training. There were no significant changes for the control group which did not train. CONCLUSION: Unilateral strength training increased the capacity of the motor cortex to drive the homogolous untrained muscles. SIGNIFICANCE: The data show for the first time that an increase in cortical drive contributes to the contralateral strength training effect.

Med Sci Sports Exerc. 1997 Jan;29(1):107-12.

Greater cross education following training with muscle lengthening than shortening.

Hortobágyi T, Lambert NJ, Hill JP.

Biomechanics Laboratory, East Carolina University, Greenville, NC 27858, USA.

The hypothesis was tested that the magnitude of cross education is greater following training with muscle lengthening than shortening. Changes in contralateral concentric, eccentric, and isometric strength and vastus lateralis and biceps femoris surface electromyographic (EMG) activity were analyzed in groups of young men who exercised the ipsilateral quadriceps with either eccentric (N = 7) or concentric (N = 8) contractions for 36 sessions over 12 wk. Control subjects (N = 6) did not train. Concentric training increased concentric strength 30% and isometric strength 22%, and eccentric training increased eccentric strength 77% and isometric strength 39% (all P < 0.05). Eccentric training improved eccentric strength three times more than the concentric training improved concentric strength (P < 0.05), and eccentric compared with concentric training improved isometric strength about 2 times more (P < 0.05). The eccentric group improved significantly from pre- to mid-training in eccentric and isometric strength (P < 0.05). The control group showed no significant changes (P < 0.05). Surface EMG activity of the vastus lateralis increased 2.2 times (pre- to mid-training), 2.8 (mid- to post-training) and 2.6 more (pre- to post-training) (P < 0.05) in the eccentric than concentric group. No significant changes in EMG activity occurred in the control group (P > 0.05). It was concluded that the greater cross education following training with muscle lengthening is most likely being mediated by both afferent and efferent mechanisms that allow previously sedentary subjects to achieve a greater activation of the untrained limb musculature.

North American Journal of Psychology, 2007, Vol. 9, No. 1 189-200

Mind Over Matter: Mental Training Increases Physical Strength

Erin M. Shackell and Lionel G. Standing

Bishop's University

This study tested whether mental training alone can produce a gain in muscular strength. Thirty male university athletes, including football, basketball and rugby players, were randomly assigned to perform mental training of their hip flexor muscles, to use weight machines to physically exercise their hip flexors, or to form a control group which received neither mental nor physical training. The hip strength of each group was

measured before and after training. Physical strength was increased by 24% through mental practice (p = .008). Strength was also increased through physical training, by 28%, but did not change significantly in the control condition. The strength gain was greatest among the football players given mental training. Mental and physical training produced similar decreases in heart rate, and both yielded a marginal reduction in systolic blood pressure. The results support the related findings of Ranganathan, Siemionow, Liu, Sahgal, and Yue (2004).

doi:10.1016/j.neuropsychologia.2003.11.018

From mental power to muscle power—gaining strength by using the mind

Vinoth K. Ranganathan, Vlodek Siemionow, Jing Z. Liu, Vinod Sahgal and Guang H. Yue

Received 3 February 2003; Revised 17 June 2003; accepted 20 November 2003. Available online 3 February 2004.

Abstract

The purposes of this project were to determine mental training-induced strength gains (without performing physical exercises) in the little finger abductor as well as in the elbow flexor muscles, which are frequently used during daily living, and to quantify cortical signals that mediate maximal voluntary contractions (MVCs) of the two muscle groups. Thirty young, healthy volunteers participated in the study. The first group (N=8) was trained to perform “mental contractions” of little finger abduction (ABD); the second group (N=8) performed mental contractions of elbow (ELB) flexion; and the third group (N=8) was not trained but participated in all measurements and served as a control group. Finally, six volunteers performed training of physical maximal finger abductions. Training lasted for 12 weeks (15 min per day, 5 days per week). At the end of training, we found that the ABD group had increased their finger abduction strength by 35% (P<0.005) and the ELB group augmented their elbow flexion strength by 13.5% (P<0.001). The physical training group increased the finger abduction strength by 53% (P<0.01). The control group showed no significant changes in strength for either finger abduction or elbow flexion tasks. The improvement in muscle strength for trained groups was accompanied by significant increases in electroencephalogram-derived cortical potential, a measure previously shown to be directly related to control of voluntary muscle contractions. We conclude that the mental training employed by this study enhances the cortical output signal, which drives the muscles to a higher activation level and increases strength.

12th Annual Congress of the ECSS, 11–14 July 2007, Jyväskylä, Finland

THE EFFECT OF PETTLEP-BASED IMAGERY ON STRENGTH PERFORMANCE

Wright Caroline, Smith Dave

(University of Chester, United Kingdom)

Neuroscience researchers have found that imaged and actual performance of motor skills share common neurophysiological mechanisms, a phenomenon termed ’functional

equivalence’ (Decety, 1996). Holmes and Collins (2001) developed the PETTLEP model of imagery based on these findings. PETTLEP is an acronym, with each letter standing

for a guideline aimed at producing functionally equivalent imagery interventions. These are Physical, Environment, Task, Timing, Learning, Emotion and Perspective.

The aim of this study was to test the model with a strength task. 50 participants were assigned to five groups: PETTLEP imagery, ’traditional’ imagery, physical practice, PETTLEP imagery combined with physical practice (PETTLEP combination) and control. Pre- and post-tests consisted of one repetition maximum (1 R.M) tests on the Cybex bicep curl machine. The PETTLEP group attended the gym, sat at the bicep curl machine and imaged completing two sets, whilst watching an internal perspective video of themselves performing a set of biceps curls. The ’traditional’ imagery group completed two sets of their imagery at home, in a relaxed position, with eyes closed. The physical practice group physically performed two sets of the task to volitional

fatigue. The combination group physically performed one set and imaged another set. Each intervention was completed twice per week for six weeks. A group x test ANOVA revealed no pre-test differences between the groups, F (4,44) = .33, p>.05, but there were

significant post-test between-group differences, F (4, 44) = 12.60, p<.01. Tukey HSD tests revealed that the PETTLEP imagery, PETTLEP combination and physical practice groups improved significantly from pre-test to post-test (p<.01) whereas the traditional imagery and control groups did not (p>.05). The PETTLEP combination group also improved to a significantly greater degree than the PETTLEP group and marginally more than the physical practice group. There was no significant difference in the magnitude of improvement shown by the PETTLEP imagery group and physical practice groups (p>.05). These results strongly support the use of PETTLEP-based imagery in enhancing strength performance. This contrasts vividly with much previous research, which showed imagery to be relatively ineffective at improving performance of strength-based tasks. However, previous research has often used more traditional ’visualisation’ imagery techniques. Therefore, sports psychologists should use the PETTLEP model in order to maximise the functional equivalence of their imagery interventions and have the greatest

positive effect on performance of strength tasks.

Decety, J. (1996). Do imagined and executed actions share the same neural substrate? Cognitive Brain Research, 3, 87-93.

Holmes, P.S. & Collins, D.J. (2001) The PETTLEP Approach to Motor Imagery: A Functional Equivalence Model for Sport Psychologists. Journal of Applied Sport Psychology, 13 (1) 60-83.

12th Annual Congress of the ECSS, 11–14 July 2007, Jyväskylä, Finland

A KNOCKOUT PSYCHOLOGICAL INTERVENTION: THE EFFECT OF PETTLEP-BASED IMAGERY ON BOXING PERFORMANCE

Smith Dave, Wright Caroline

(University of Chester, United Kingdom)

Holmes and Collins (2001) developed the PETTLEP model to help practitioners produce functionally equivalent imagery. PETTLEP is an acronym, each letter representing

a key issue to consider when implementing imagery interventions: Physical, Environment, Task, Timing, Learning, Emotion and Perspective. Recent studies suggest

that PETTLEP-based imagery interventions are more effective than more traditional interventions (Smith, Wright, Allsopp & Westhead, in press). However, it will not always

be possible to incorporate all the guidelines into imagery interventions, and therefore information regarding the effects of interventions focusing on different PETTLEP components would be useful. Also, the model still needs to be comprehensively tested with various skills. Therefore, this study examined the effects of interventions focused

on the environment and timing components of PETTLEP in boxing. Fifty-two amateur boxers were divided into three groups: An ’environment’ group, a ’timing’ group and a control group. Participants performed pre-tests and post-tests consisting of three commonly-used punch combinations against a defensive boxer using pads. A qualified boxing judge scored the punches. Following the pre-test, imagery participants imaged performing the combinations successfully three times per week for six weeks. The timing group imaged at home whilst listening to an audio recording of them performing successful combinations. This recording acted as a template enabling participants to image in ’real time’ (cf. Smith & Holmes, 2004). The environment group imaged in the boxing ring where testing took place, dressed in their boxing clothing. Controls read boxing literature. A group x test ANOVA for performance scores revealed a significant interaction effect, F (2,45) = 10.67, p<.001. Tukey HSD tests revealed that both imagery groups improved significantly between pre- and post-tests, with the environment group improving to a significantly greater degree than the timing group, but the control group did not improve. These results support the efficacy of interventions focusing on the environment and timing PETTLEP components, and suggest that the environment component is particularly important to obtain optimal results from imagery. Implications for practitioners will be explored, and practical recommendations suggested, regarding the incorporation of these PETTLEP components into imagery interventions.

References:

Holmes, P. S., & Collins, D. J. (2001). The PETTLEP approach to motor imagery: A functional equivalence model for sport psychologists. Journal of Applied Sport Psychology, 13, 60-83.

Smith, D., Wright, C., Allsopp, A., & Westhead, H. (in press). It’s all in the mind: PETTLEP-based imagery and sports performance. Journal of Applied Sport Psychology.

Smith, D., & Holmes, P. (2004). The effect of imagery modality on golf putting performance. Journal of Sport and Exercise Psychology, 26, 385-395.

Journal of Imagery Research in Sport and Physical Activity

Vol. 2 (2007) / Issue 1 / Articles

The Effect of a Short-term PETTLEP Imagery Intervention on a Cognitive Task

Caroline J. Wright, University of Chester
Dave K. Smith, University of Chester

Abstract

Based on neuroscience research, the PETTLEP model was developed by Holmes and Collins (2001). The model provides imagery guidelines which identify seven key factors (physical, environment, task, timing, learning, emotion, perspective) that should be included when developing interventions to maximise functional equivalence. This study explored the effect of a short-term PETTLEP imagery intervention, compared to `traditional' imagery, on a computer game: Need for Speed Underground 2 (EA games). Eighty participants were randomly assigned to one of four groups: PETTLEP imagery group, `traditional' imagery group, physical practice group and control group. After three practice attempts, pre-tests consisted of five attempts at the game. The game involved completing timed laps by manoeuvring a vehicle around a track using the computer's arrow keys. The PETTLEP group completed individualised response training, and then performed imagery sitting in front of the computer screen and repeatedly imaging themselves completing the task. The `traditional' imagery group was sat in a separate room, given individualised stimulus training and instructed to relax and close their eyes during imagery. The physical practice group performed the actual task. Each intervention lasted for forty-five minutes, immediately followed by the post-test, which again consisted of five attempts at the game. A group x test ANOVA showed that the PETTLEP imagery group and physical practice group both improved significantly from pre-test to post-test (p<0.05). However, there was no significant difference in the magnitude of their improvements. The traditional imagery and control groups showed no increase in performance from pre-test to post-test (p>0.05). The results strongly support the use of PETTLEP in enhancing performance on a cognitive task. Contrary to previous studies, PETTLEP was as effective as physical practice. This finding could have important implications for athletes returning from injury, suffering from over-training and for use in pre-performance routines. Therefore, sports psychologists should maximise the functional equivalence of their imagery interventions to have the greatest positive effect on performance on such cognitive tasks, at least in the short term. Future research needs to focus on applying short-term PETTLEP interventions to different tasks, varying in cognitive complexity. Assessing the effectiveness of PETTLEP imagery used in various combinations with physical practice would also be a useful addition to the literature.

J Adv Nurs. 2008 Aug;63(3):259-65.

Effect of PETTLEP imagery training on performance of nursing skills: pilot study.

Wright C, Hogard E, Ellis R, Smith D, Kelly C.

Department of Sport and Exercise Science, University of Chester, UK.

AIM: This article is a report of a study to evaluate the effect of PETTLEP-based imagery training on nursing skill performance. BACKGROUND: Imagery structuring has been demonstrated to facilitate the development of psychomotor skills in sporting performance. A form of imagery structuring known as PETTLEP was employed in this study. PETTLEP (an acronym for its procedures) involves preparation through focussing on physical characteristics, the environment, the task itself, timing, learning, emotion and perspective. METHODS: A pilot study was conducted, using experimental design, and the data were collected in 2005. Participants in the experiment were 56 pre-registration students from one university in the United Kingdom. Half of the students received training for two basic nursing skills using PETTLEP procedures, and scores were compared for two objective structured clinical examinations. RESULTS: Students who received PETTLEP training for blood pressure measurement performed statistically significantly better than those who did not (F = 4.62 P = <0.05). The training did not have a statistically significant effect for aseptic techniques. We suggest that the psychomotor element in aseptic techniques was not as important as that involved in blood pressure measurement. CONCLUSION: PETTLEP imagery should be explored further as a method to help nursing students acquire skills that have a psychomotor component.

Res Q Exerc Sport. 2008 Sep;79(3):385-91.

Beating the bunker: the effect of PETTLEP imagery on golf bunker shot performance.

Smith D, Wright CJ, Cantwell C.

Department of Sport and Exercise Psychology, Manchester Metropolitan University, UK.

The aim of this study was to compare the effects of physical practice with PETTLEP-based (Physical, Environment, Task, Timing, Learning, Emotion and Perspective; Holmes & Collins, 2001) imagery and PETTLEP + physical practice interventions on golf bunker shot performance. Thirty-two male county- or international-level golfers were assigned to one of four groups; PETTLEP imagery, physical practice, PETTLEP + physical practice, or control. The PETTLEP imagery group imaged 15 bunker shots, their interventions incorporating PETTLEP components, such as physical, environment, and emotion, twice a week. The physical practice group physically performed their 15 bunker shots twice per week; the PETTLEP + physical practice group performed PETTLEP imagery once per week and physical practice once per week. Each group performed their respective tasks for 6 weeks. Pre- and posttests consisted of 15 bunker shots, with points awarded according to the ball proximity to the pin. All groups improved significantly (p < .01) from pre- to posttest, and the PETTLEP + physical practice group improved more (p < .05) than the PETTLEP and physical practice groups. However, there was no significant difference between the physical practice and PETTLEP groups (p > .05). Findings, therefore, support the effectiveness of PETTLEP in enhancing golf performance, especially when combined with physical practice.

J Neural Transm. 2007;114(10):1265-78. Epub 2007 Jun 20.

Motor imagery and action observation: cognitive tools for rehabilitation.

Mulder T.

Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands.

Rehabilitation, for a large part may be seen as a learning process where old skills have to be re-acquired and new ones have to be learned on the basis of practice. Active exercising creates a flow of sensory (afferent) information. It is known that motor recovery and motor learning have many aspects in common. Both are largely based on response-produced sensory information. In the present article it is asked whether active physical exercise is always necessary for creating this sensory flow. Numerous studies have indicated that motor imagery may result in the same plastic changes in the motor system as actual physical practice. Motor imagery is the mental execution of a movement without any overt movement or without any peripheral (muscle) activation. It has been shown that motor imagery leads to the activation of the same brain areas as actual movement. The present article discusses the role that motor imagery may play in neurological rehabilitation. Furthermore, it will be discussed to what extent the observation of a movement performed by another subject may play a similar role in learning. It is concluded that, although the clinical evidence is still meager, the use of motor imagery in neurological rehabilitation may be defended on theoretical grounds and on the basis of the results of experimental studies with healthy subjects.

Stroke. 2007 Apr;38(4):1293-7. Epub 2007 Mar 1.

Mental practice in chronic stroke: results of a randomized, placebo-controlled trial.

Page SJ, Levine P, Leonard A.

Department of Physical Medicine and Rehabilitation, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0530.

BACKGROUND AND PURPOSE: Mental practice (MP) of a particular motor skill has repeatedly been shown to activate the same musculature and neural areas as physical practice of the skill. Pilot study results suggest that a rehabilitation program incorporating MP of valued motor skills in chronic stroke patients provides sufficient repetitive practice to increase affected arm use and function. This Phase 2 study compared efficacy of a rehabilitation program incorporating MP of specific arm movements to a placebo condition using randomized controlled methods and an appropriate sample size. Method- Thirty-two chronic stroke patients (mean=3.6 years) with moderate motor deficits received 30-minute therapy sessions occurring 2 days/week for 6 weeks, and emphasizing activities of daily living. Subjects randomly assigned to the experimental condition also received 30-minute MP sessions provided directly after therapy requiring daily MP of the activities of daily living; subjects assigned to the control group received the same amount of therapist interaction as the experimental group, and a sham intervention directly after therapy, consisting of relaxation. Outcomes were evaluated by a blinded rater using the Action Research Arm test and the upper extremity section of the Fugl-Meyer Assessment. RESULTS: No pre-existing group differences were found on any demographic variable or movement scale. Subjects receiving MP showed significant reductions in affected arm impairment and significant increases in daily arm function (both at the P<0.0001 level). Only patients in the group receiving MP exhibited new ability to perform valued activities. CONCLUSIONS: The results support the efficacy of programs incorporating mental practice for rehabilitating affected arm motor function in patients with chronic stroke. These changes are clinically significant.

PHYS THER
Vol. 85, No. 10, October 2005, pp. 1053-1060

Can Mental Practice Increase Ankle Dorsiflexor Torque?

Ben Sidaway and Amy (Robinson) Trzaska

B Sidaway, PT, PhD, is Professor, Department of Physical Therapy, Husson College, One College Cir, Bangor, ME 04401 (USA)
A Trzaska, PT, MPT, is Physical Therapist, Family Practice Center, Portland, Me. She was a student in the Department of Physical Therapy, Husson College, during data collection

Submitted September 27, 2004; Accepted March 22, 2005

Background and Purpose. Mental practice has been shown to beeffective in increasing the force production of the abductordigiti minimi muscle in the hand. The aim of this study wasto determine whether mental practice could produce strengthgains in the larger ankle dorsiflexor muscles, which are importantduring walking. Subjects. Twenty-four subjects were randomlyassigned to a physical practice group, a mental practice group,or a control group (8 subjects per group). Methods. In the practicegroups, subjects either physically or mentally practiced producingmaximal isometric contractions for 3 sets of 10 repetitions,3 times per week for 4 weeks. Changes in mean peak isometrictorque normalized to body weight and the resulting percentageof improvement were analyzed across the 3 groups. Results. Differencesin raw torque production after training in the 2 practice groupsresulted in significant percentages of improvement for the physicalpractice group (25.28%) and the mental practice group (17.13%),but not for the control group (–1.77%). The 2 practicegroups were not statistically different in their maximal torque-generatingcapacity after training. Discussion and Conclusion. These findingsshow that mental practice in people without impairments canlead to an increase in torque production similar to that producedby physical practice. Such a technique may prove to be a usefuladjunct to traditional treatment options aimed at increasingmuscle strength.

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