Passive insufficiency of two-joint shoulder muscles.

Abstract

This preliminary study examined the effects of full elbow flexion and full elbow extension on the end-point of active range of motion of shoulder flexion and shoulder extension respectively. The end-points were measured from lateral photographs of the right upper limbs of 30 men after they flexed and extended their shoulders with their elbows held in full flexion and full extension. Angular measurements showed that full elbow flexion limited shoulder flexion range of motion and that full elbow extension limited shoulder extension range of motion. The results indicated that passive muscle insufficiency of active shoulder flexion and extension was probably brought about by lengthening the triceps brachii and the biceps brachii muscles respectively. Clinicians are encouraged to considerthis passive insufficiency when measuring range of motion of shoulderflexion and extension and when implementing therapeutic interventions.