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 musculature during performance of a weight relief raise. Intramuscular electromyographic activity of 12 shoulder muscles was recorded in 13 pain-free subjects with paraplegia while elevating the trunk from a sitting position. Upper extremity motion was determined by elbow electrogoniometry and video recordings. Three phases of the raise were analyzed: initial loading, lift, and hold. During the lift phase, high level triceps long head activity (54% manual muscle test [MMT]) produced elbow extension, whereas moderate- to high-level activity of the sternal pectoralis major (32% MMT) and latissimus dorsi (58% MMT) elevated the trunk on the fixed humerus. Deltoid, supraspinatus, infraspinatus, subscapularis, middle trapezius, serratus anterior, and biceps long head played minimal roles (< 25% MMT). Thoracohumeral muscle activity, by transferring the load on the humerus directly to the trunk, functionally circumvented the glenohumeral joint. This would reduce the potential for impingement of the rotator cuff.
Reyes
M L
ML
Rancho Los Amigos Medical Center, Pathokinesiology Laboratory, Downey, CA 90242, USA.
Gronley
J K
JK
Newsam
C J
CJ
Mulroy
S J
SJ
Perry
J
J
D000328:Adult; D004576:Electromyography; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010264:Paraplegia / Q000503:physiopathology* / Q000534:rehabilitation; D026741:Physical Therapy Modalities; D003668:Pressure Ulcer / Q000517:prevention & control; D012782:Shoulder / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology / Q000534:rehabilitation