Increased Tone and Stiffness of the Teres Major Muscle in Elite Handball Athletes: A Cross-Sectional Study

Abstract

Background: The aim of this study was to determine whether the elite handball (HB) athletes with glenohumeral internal rotation deficit (GIRD) present differences in the mechanical properties in the teres major muscle, and strength and extensibility of the posterior shoulder tissues of the throwing shoulder (TS) compared to the non-throwing (non-TS) and non-HB athletes. Methods: A cross-sectional study was carried out, with sixty male participants: 30 HB athletes with GIRD and 30 age-matched healthy non-HB athletes. Mechanical properties of the teres major muscle were measured with MyotonPRO; also, extensibility of the posterior shoulder tissues and maximum isometric internal rotation (IR) and external rotation (ER) strength were recorded. Results: The teres major muscle of the TS in the HB group achieved a higher tone (Δ 0.34; 95% CI: 0.15, 0.53) and stiffness (Δ 30.86; 95% CI: 23.04,38.68), and a lower relaxation time compared to the non-TS of the same group (Δ −0.69; 95% CI: −1.15, −0.24;) and to the TS of the control group for the tone (Δ 0.36; 95% CI: 0.02, 0.70) and for the stiffness (Δ 27.03; 95% CI: 15.24, 38.83). The extensibility of the TS of the HB group presented a statistically significant decrease compared to the control group (Δ−7.83; 95% CI: −12.42, 3.23). A between-groups ER/IR ratio imbalance was found for the TS (Δ−12.18; 95% CI: −25.59, −1.23) and the non-TS (Δ−13.01; 95% CI: −25.79, −0.25). Conclusions: HB athletes with GIRD present a higher tone and stiffness of the teres major muscle and lack of extensibility of the tissues of the posterior part of the shoulder compared to the non-TS and to healthy non-HB athletes.