Electromyographic activity in the immobilized shoulder girdle musculature during contralateral upper limb movements

The purpose of this study was to quantify electromyographic (EMG) activity in the immobilized shoulder girdle musculature at rest and during a battery of contralateral upper limb activities. Six asymptomatic men, aged 22 to 33 years, volunteered to participate. Fine-wire (supraspinatus, infraspinatus) and surface (deltoids, trapezii, biceps, serratus anterior) electrodes recorded the mean peak normalized (percent maximal voluntary contraction [%MVC]) EMG activity from each immobilized muscle at rest and during slow, fast, and incrementally resisted contralateral upper limb motions (5, 15, and 25 lb). EMG activity in all muscles was low during quiet immobilized standing (45% MVC) with low supraspinatus, biceps, and anterior deltoid activities (