Date of Award

Spring 5-1-2014

Document Type

Thesis

Degree Name

Master of Science in Athletic Training

Department

Applied Medicine and Rehabilitation

Abstract

Context: Dyskinesis has been linked to deficits in muscular strength and neuromuscular control of the scapular stabilizers. Often, when treating overhead athletes with pathological shoulders, Athletic Trainers focus on rotator cuff and scapular muscle strength to find resolution, yet the role of the lower trapezius strength in scapular dyskinesis is not well understood. Objective: To identify differences among varying levels of scapular dyskinesis on lower trapezius muscle thickness and strength. To identify the relationship between lower trapezius muscle thickness and strength with varying levels of scapular dyskinesis . To identify the relationship between pain and function within varying levels of scapular dyskinesis. Design: Ex-post-factor descriptive design. Setting: Indiana State University Applied Medicine Research Center. Participants: Fifty participants (age=25.18±5.90y; mass=71.67±13.15kg; height=173.5±10.2in; males=23/50, 46%, females=27/50, 64%; right-handed=48/50, 96%, left-handed=2/50, 4%) completed the study. Interventions: We evaluated scapular dyskinesis using the clinical visualization technique identifying each scapula as normal, with subtle or with obvious dyskinesis. Participants, depending on body mass, lifted a 3lb (mass150lb [68kg]) weight overhead in flexion (5 repetitions) and abduction (5 repetitions), while a trained clinician observed for normal scapulohumeral rhythm, dysrhythmia, or scapular winging. Participants completed the Penn Shoulder Scale, a reliable and internally consistent self-report questionnaire with subscales on pain (0-30 points) and function (0-60 points). Main Outcome Measures: We evaluated strength with a hand-held dynamometer (microFET2, iv Hoggan Scientific, ±1%) with a single arm outstretched overhead in a “Y” position. The strength testing was performed at the same time as the diagnostic ultrasound (GE LOGIQ®e 2008) measurement of muscle thickness. We used separate one way analyses of variance to examine the size and strength of the lower trapezius and compared it over three levels of scapular dyskinesis to identify the differences in the dominant limb (DL) and non-dominant limb (NDL). We used a Spearman rho correlation to determine the relationship between scapular dyskinesis, muscle strength, and muscle thickness in DLs and NDLs. We conducted Kruskal-Wallis non-parametric one-way analyses of variance to compare pain and function subscales over the three levels of scapular dyskinesis in dominant and non-dominant limbs. Results: We did not identify any significant differences between DL scapular dyskinesis visual inspection categories on the strength (F2,49=0.596, p=0.555, 1-β=0.93) and thickness variables (F2,48=0.714, p=0.495, 1-β=0.51). We did not identify any significant difference between NDL scapular dyskinesis visual inspection categories on the strength (F2,49=2.382, p=0.103, 1-β=0.96) and thickness variables (F2,47=0.631, p=0.537, 1-β=0.54). We identified no significant correlation between DL or NDL scapular dyskinesis and strength (DL Spearman’s rho= -0.160, p=0.266; NDL Spearman’s rho=-0.106, p=0.466) or thickness (DL Spearman’s rho=-0.175, p=0.230; NDL Spearman’s rho=-0.091, p=0.537). We did identify a significant and strong relationship between DL strength and thickness (Spearman’s rho=0.706, p

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