| Summary: | 碩士 === 國立臺灣大學 === 物理治療學研究所 === 107 === Background: The repetitive overhead movements with wide range of motion and high velocity are required in overhead sports activity. It may give rise to shoulder region muscles overloading and fatigue. Altered scapular kinematics and muscle activities was found in overhead athletes with shoulder pathology, especially the overactivity of upper trapezius (UT) muscle which might cause muscle fatigue and myofascial trigger point (MTrP). Numerous studies have investigated the effects of shoulder muscle fatigue. However, the effects of UT hosting MTrP and UT muscle fatigue is still unknown. Objective: The purposes of the study were to (1) compare the scapular kinematics and muscle activities during arm elevation in overhead athletes with and without UT MTrPs; (2) compare the effects of scapula elevation fatigue task on the scapular kinematics and muscle activities during arm elevation in overhead athletes with and without UT MTrPs. Design: Participants with UT MTrP and without UT MTrP were recruited in this study. Each patient preformed a scapular elevation fatigue task until they could not maintain over a half of peak force for 5 seconds. Three-dimensional electromagnetic motion analysis system and electromyography muscle activity were used to record scapular kinematics and muscle activation during scapular plane arm elevation before and after the fatigue task. Main outcome measure: Scapular kinematics (upward/downward rotation, external/internal rotation, posterior/anterior tilt) and muscle activity (upper trapezius, lower trapezius, serratus anterior, and UT/LT, UT/ SA) were the outcomes of the study. Results: There was no group difference in scapular kinematics and muscle activities during scapular plane arm elevation, except for higher activity of LT in MTrP group. In comparisons of pre- and post-fatigue condition, increased activity of UT (eccentric phase) and LT, as well as decreased UT/LT ratio were found after fatigue protocol without group difference. Conclusion: Based on our results, it does not support that the presence of UT MTrP is related to the scapular kinematics impairment during arm elevation in overhead athletes even after muscle fatigue task. The lower trapezius muscle may be the main compensatory scapular upward rotator when the UT dysfunction occurs due to the presence of MTrP.
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