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Abstract: Smith J, Dahm DL, Kotajarvi BR, Boon AJ, Laskowski ER, Jacofsky DJ, Kaufman KR. Electromyographic activity in the immobilized shoulder girdle musculature during ipsilateral kinetic chain exercises. Objective: To quantify the electromyographic activity in the shoulder girdle musculature during ipsilateral kinetic chain exercises performed in a shoulder immobilizer in asymptomatic men. Design: Descriptive. Setting: Motion analysis laboratory at a tertiary care center. Participants: Five asymptomatic male volunteers, ages 24 to 32 years. Intervention: Fine-wire (supraspinatus, infraspinatus, upper subscapularis) and surface (deltoids, trapezii, biceps, serratus anterior) electrodes recorded electromyographic activity from each muscle during a split-stance cross-body rotation (twisting to the opposite side at high, mid, and low levels), split stance attempted ipsilateral floor touch, and attempted overhead reach. All movements were initiated from the immobilized scapula and were tested with and without a combined step. Main Outcome Measure: Mean peak normalized (percentage of maximum voluntary contraction [%MVC]) electromyographic activity of each muscle during each exercise. Results: For all exercises, biceps and infraspinatus activity remained low (<10% MVC), whereas upper subscapularis activity was moderate to very high (29%−68% MVC). Supraspinatus activity was low (<20% MVC) for all motions except the attempted overhead reach (23% MVC). Serratus electromyographic activity was less than 20% of MVC for all motions and was most responsive to added stepping (23%−136% MVC without stepping vs 24%−199% MVC with stepping). Cross-body rotation at lower heights progressively increased serratus activity while decreasing supraspinatus, upper trapezius, and anterior deltoid activity. Conclusions: Based on these electromyographic data, selected kinetic chain exercises could potentially be implemented during periods of shoulder immobilization. All exercises examined could potentially be safe after superior labral anteroposterior repair, but not after subscapularis repair. All exercises, with the exception of the attempted overhead reach, could potentially be safe after supraspinatus repair, with or without concomitant infraspinatus repair. Early activation of the serratus anterior could potentially be achieved by performing cross-body rotations, particularly at lower heights. [Copyright &y& Elsevier]

Abstract: Smith J, Dahm DL, Kaufman KR, Boon AJ, Laskowski ER, Kotajarvi BR, Jacofsky DJ. Electromyographic activity in the immobilized shoulder girdle musculature during scapulothoracic exercises. Objective: To quantify the electromyographic activity in the shoulder girdle musculature during scapulothoracic exercises performed in a shoulder immobilizer in asymptomatic men. Design: Descriptive. Setting: Motion analysis laboratory at a tertiary care center. Participants: Five asymptomatic male volunteers ages 24 to 32 years. Intervention: Fine-wire (supraspinatus, infraspinatus, upper subscapularis) and surface (deltoids, trapezii, biceps, serratus anterior) electrodes recorded electromyographic activity from each muscle during scapular clock, elevation, depression, protraction, and retraction exercises completed during a single testing session in random order. Main Outcome Measure: Mean peak normalized (percentage of maximal voluntary contraction [MVC]) electromyographic activity of each muscle during each exercise. Results: Biceps activity was uniformly low (<20% MVC), whereas upper subscapularis activity was uniformly high (40%−63% MVC). Both scapular depression and protraction elicited low activity (<20% MVC) in the supraspinatus, infraspinatus, anterior deltoid, and biceps brachii muscles, while generally producing greater than 20% MVC activity in the trapezii and serratus. Scapular depression produced the largest serratus anterior activity (47% MVC). Conclusions: These data are the first to describe the electromyographic activity during scapulothoracic exercises while in a shoulder immobilizer. Based on electrophysiologic data in normal volunteers, our findings suggest that during periods of shoulder immobilization: (1) scapular depression and protraction exercises could potentially be safely performed after rotator cuff repair to facilitate scapulothoracic rehabilitation, (2) all exercises studied could potentially be safe after superior labral anteroposterior shoulder repair, and (3) all exercises studied should be avoided after subscapularis repair. Further investigation in symptomatic individuals may facilitate refinement of these recommendations. [Copyright &y& Elsevier]

Abstract: Kotajarvi BR, Basford JR, An K-N, Morrow DA, Kaufman KR. The effect of visual biofeedback on the propulsion effectiveness of experienced wheelchair users. Objective: To determine the effect of visual feedback on the propulsion effectiveness of experienced manual wheelchair users. Design: Controlled trial. Setting: A motion analysis laboratory. Participants: A convenience sample of 16 healthy men and 2 healthy women with T4-L2 traumatic paraplegia, a mean age of 38±9 years, and a mean duration of manual wheelchair-based mobility of 14±8 years. Intervention: Propulsion was assessed as the subjects propelled an instrumented wheelchair (with and without visual biofeedback) on a custom-built dynamometer at propulsion intensities of .15 and .25W/kg for 10 minutes. Main Outcome Measures: The primary outcome variable was the fraction of effective force (FEF) (ie, the ratio of effective to total force) applied by the subject to the wheelchair’s pushrim. Secondary variables included velocity, stroke frequency, and stroke angle. Results: A 2-factor analysis of variance with repeated measurements was used to detect significant differences between the outcome variables. The FEF ratio was 73.9% without feedback and 72.5% with feedback at the lower-intensity level. Propulsion during the higher intensity condition both with and without feedback resulted in a statistically significant improvement in the FEF (73.9%–78.7% with no feedback, 72.5%–80.2% with feedback), compared with the lower-intensity level. Stroke angle increased from 84.3° to 98.7° and frequency decreased from 66 to 57.8 strokes/min with feedback. Conclusions: Visual biofeedback may have little utility in improving the force effectiveness of manual wheelchair propulsion in experienced wheelchair users. Experienced wheelchair users may have already optimized their stroke in a manner that balances energy expenditure with stroke efficiency. Other variables such as stroke length and frequency may be more amenable to visual biofeedback. [Copyright &y& Elsevier]