Author(s): LIO, C., CHUNG WEI, Y.J., HUANG, T.S., Institution: NATIONAL YANG MING CHIAO TUNG UNIVERSITY, Country: TAIWAN, Abstract-ID: 1092

INTRODUCTION:
Scapular dyskinesis (SD), defined as altered scapular positioning and motion, is prevalent in competitive swimmers due to the high functional demands of repetitive overhead strokes. These repetitive activities induce fatigue in the rotator cuff and scapular stabilizers, which can subsequently impair the scapulohumeral rhythm. While previous studies have focused primarily on the association between the presence of SD and shoulder pain, limited research has examined swimmers with recurrent shoulder pain. Given that history of previous shoulder pain is one of the factors contributing to recurrent shoulder pain in swimmers, identifying the specific musculoskeletal profiles of swimmers with both SD and recurrent pain is essential. Therefore, this study aimed to identify the musculoskeletal characteristics associated with SD in competitive swimmers with recurrent shoulder pain.
METHODS:
A total of 54 competitive swimmers with history of shoulder pain from high schools and colleges were recruited, 30 participants were categorized into SD groups and 24 participants in the non-SD group using the Scapular Dyskinesis Test. The testing items of musculoskeletal characteristics included shoulder and trunk range of motion (ROM); cervical and thoracic posture; latissimus dorsi and pectoralis minor muscle length; glenohumeral joint laxity and generalized joint hypermobility; shoulder and periscapular muscle strength and fatigue resistance; scapulothoracic and glenohumeral joint control ability, and upper quarter dynamic balance performance. Independent t-test and Mann Whitney U test were used to analyze group differences.
RESULTS:
The results showed that the trunk flexion ROM was significantly lower in the SD group compared to the non-SD group (p = 0.024). Furthermore, the SD group exhibited a significant increase in SA strength following the fatigue protocol, whereas the non-SD group showed a decrease. (p = 0.009). Swimmers with generalized joint hypermobility were significantly less likely to exhibit SD (p = 0.033), while short-distance specialists showed a significantly higher prevalence of SD compared to middle-distance swimmers (p = 0.02). Within the SD group, participants with recurrent shoulder pain showed significantly lower serratus anterior: lower trapezius strength ratio (p = 0.009) and greater medial reach of the Upper Quarter Y-Balance Test compared to those without recurrent shoulder pain (p = 0.042).
CONCLUSION:
These findings suggest that thoracic flexion mobility and joint hypermobility are associated with SD in competitive swimmers. Short-distance specialists are at greater risk for SD development. Furthermore, Swimmers with both SD and recurrent pain exhibit significant periscapular muscle imbalance, enhanced fatigue resistance of serratus anterior, and greater upper quarter dynamic balance performance.