ELECTROMYOGRAPHIC ANALYSIS OF SHOULDER MUSCLES OF MEN WITH LOW-LEVEL PARAPLEGIA DURING A WEIGHT RELIEF RAISE

The purpose of this study was to define the demand on the shoulder mus culature during performance of a weight relief raise. Intramuscular el ectromyographic activity of 12 shoulder muscles was recorded in 13 pai n-free subjects with paraplegia while elevating the trunk from a sitti ng position. Upper extremity motion was determined by elbow electrogon iometry and video recordings. Three phases of the raise were analyzed: initial loading, lift, and hold. During the lift phase, high level tr iceps long head activity (54% manual muscle test [MMT]) produced elbow extension, whereas moderate- to high-level activity of the sternal pe ctoralis major (32% MMT) and latissimus dorsi (58% MMT) elevated the t runk on the fixed humerus. Deltoid, supraspinatus, infraspinatus, subs capularis, middle trapezius, serratus anterior, and biceps long head p layed minimal roles (<25% MMT). Thoracohumeral muscle activity, by tra nsferring the load on the humerus directly to the trunk, functionally circumvented the glenohumeral joint. This would reduce the potential f or impingement of the rotator cuff. (C) 1995 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medici ne and Rehabilitation