Scapular orientation following repetitive prone rowing: implications for potential subacromial impingement mechanisms.
While fatigue of the rotator cuff demonstrably causes superior humeral head migration and concomitant risk of impingement, the relationship between specific muscular fatigue, scapular dyskinesis and impingement risk is less clear. The purpose of this study was to examine changes in scapular orientation following a simulated prone rowing fatiguing protocol that targeted the scapula stabilizing muscles while attempting to alleviate rotator cuff muscular demands. Scapular orientation and muscle activity were collected from participants before and immediately after the fatiguing task. This task fatigued both the stabilizing (upper and middle trapezius, and latissimus dorsi) and rotator cuff (supraspinatus, and infraspinatus) muscles. The upper extremity muscle fatigue pattern caused by the protocol did not elicit any significantly changes in three-dimensional scapular position with all post-fatigue changes being ≤ 1° (p = 0.17-0.58). These results indicated that scapular reorientation is likely not the dominant mechanism of fatigue-induced subacromial impingement development. However, the substantial variability present in the kinematics prevents complete exclusion of scapular dyskinesis as a secondary causal mechanism of impingement.
Department of Kinesiology, University of Waterloo, Waterloo N2L 3G1, Canada.
Mamiko
M
Noguchi
Jaclyn N
JN
Chopp
Stephanie P
SP
Borgs
Clark R
CR
Dickerson
D000328:Adult; D001265:Athletic Injuries / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D009132:Muscles; D016684:Prone Position / Q000502:physiology*; D017006:Rotator Cuff / Q000503:physiopathology; D012540:Scapula / Q000503:physiopathology*; D012782:Shoulder / Q000503:physiopathology; D019534:Shoulder Impingement Syndrome / Q000503:physiopathology*; D013177:Sports / Q000502:physiology*; D013647:Task Performance and Analysis
Fatigue; Scapular orientation; Scapulothoracic muscles; Shoulder; Subacromial impingement