Purpose: The aim of this study was to investigate the effect of alterations in muscle length of the biceps in various elbow postures during shoulder elevation and muscle activation.
Methods: Participants aged 5 years and older with a birth brachial plexus injury were asked to perform elevation shoulder (abduction and flexion) in 7 elbow conditions. Surface electromyography was applied to bilateral biceps and triceps.
Results: Peak shoulder elevation was present in the immobilized 20° elbow posture. Muscle activity of the triceps and biceps was impacted by the elbow posture via immobilization.
Conclusions: Elbow postures in elongated postures, via immobilization, may result in higher shoulder elevation due to increased passive forces when there is an altered muscle state of the biceps in this population. Clinicians should consider the optimal elbow joint posture (<30°) to improve overhead reaching in this population.
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