Investigation of factors associated with shoulder pain in elite male high school soft tennis players

BACKGROUND: Soft tennis is a racket sport involving frequent overhead motions that is popular in Asia, especially among high school students in Japan. In other overhead sports, such as baseball and tennis, lower kinetic chain elements, such as hip range of motion (ROM), have been implicated in the development of shoulder pain. However, their specific involvement has not been fully clarified. METHODS: In this observational cross-sectional study, we evaluated 160 elite male high school soft tennis players. Collected data included participant characteristics, history of shoulder pain, and passive shoulder and hip ROM. Three logistic regression models were constructed: Model 1 (height + shoulder ROM), Model 2 (height + hip ROM), and Model 3 (height + shoulder and hip ROM). Model performance was assessed using the Akaike Information Criterion (AIC), the Bayesian Information Criterion (BIC), and the area under the curve (AUC). RESULTS: Model 3 demonstrated the best overall fit (AIC: 185.1, BIC: 197.4, AUC: 0.73); however, the improvement over Model 1 was marginal in practical terms. Glenohumeral internal rotation deficit (GIRD) and height were significantly associated with shoulder pain, whereas hip ROM variables were not. CONCLUSIONS: GIRD and shorter stature were associated with shoulder pain in elite male high school soft tennis players. Hip ROM was not directly associated with shoulder pain. This study is the first to investigate shoulder pain-related factors in elite adolescent soft tennis players by systematically comparing shoulder ROM-only, hip ROM-only, and combined models, demonstrating greater explanatory performance for models incorporating shoulder ROM.