Electromyographic and kinematic analysis of the shoulder during four activities of daily living in men with C6 tetraplegia.

The pattern of motor paralysis that commonly follows C6 tetraplegia creates an increased demand on upper limb function. The present investigation documented shoulder motion and muscular activity during planar motions and four activities of daily living (ADLs) in 15 men with spinal cord injuries (SCI) resulting in C6 tetraplegia. Three-dimensional (3-D) shoulder motion was recorded using a VICON motion system, and intramuscular electrodes recorded electromyographic (EMG) activity of 12 shoulder muscles. Active flexion and abduction required greater EMG than control subjects lifting a 2-kg weight. Relative EMG was similar for most muscles during hair combing, drinking, and reaching forward, although increased humeral elevation commonly resulted in a greater relative muscular effort. Hair combing had the most humeral elevation (90 degrees) with moderate to high levels of activation (32% to 63% maximum) recorded in the anterior deltoid, supraspinatus, infraspinatus, and scapular muscles. During reaching for the perineum, posterior deltoid and subscapularis activity dominated.