Author(s): CARUSO, L., BUSATTO, L., DE SANTIS, E., PIVA, G., LAMBERTI, N., MANFREDINI, F., VACCAREZZA, M., Institution: UNIVERSITY OF FERRARA, Country: ITALY, Abstract-ID: 2160

INTRODUCTION:
The shoulder is one of the most heavily loaded joints in overhead sports, particularly elite-level volleyball, where repetitive high-speed movements impose substantial mechanical demands. Effective neuromuscular control and the ability to exert force are essential for optimal performance and injury prevention. However, there is limited longitudinal data on the seasonal evolution of shoulder strength in high-level athletes, which reduces our understanding of role- and angle-specific changes and compromises the optimisation of preventive protocols and load management. This study aims to characterise these patterns to support targeted, periodized preventive strategies.
METHODS:
Thirteen elite right-handed female volleyball players from a Romanian top-division team (aged 19–35) were assessed longitudinally at three time points across the season—start (T0), mid-season (T1), and end (T2)—using a PitchSix Force Board digital dynamometer. Athletes were categorised by role (9 hitters, 2 setters, 2 liberos). Strength was assessed bilaterally and included isometric IR and ER at 0°, 45°, 60°, and 90° of abduction and the Jobe test at 30°. Joint mobility was assessed via GIRD and external-rotation ROM. All tests were performed under standardised conditions with two trials per limb (5-s maximal isometric contractions; 15-s rest between trials).
RESULTS:
At T0, 13 elite athletes displayed role- and angle-dependent IR/ER profiles, showing differences by role and angle with a slightly imbalanced IR/ER ratio. In hitters, baseline 60° IR strength was 6.65 kg (±1.35). Between T0 and T1, all roles showed a marked increase in strength, with hitters showing the most marked increase at 0°-60° (+13-28%), followed by setters at 45°-90° (+5-27%), and liberos at 0°-90° (+6-46%). Some increases stabilised or decreased between T1 and T2, whilst hitters and liberos showed more marked decreases at 60°-90°. The Jobe test at 30° showed similar trends (+8-27% T0-T1; -4/-16% T1-T2), with a stable symmetry index (0.96-1.16). The balance index showed IR predominance at reduced abduction angles. At T2, four hitters had elevated GIRD (24°), while TROM indicated preserved total ROM.
CONCLUSION:
The data show that the seasonal evolution of shoulder isometric strength has clear angle- and role-specific patterns during the competitive season. Key findings were a progressive functional imbalance at high angles and more marked decreases in ER strength at 60°–90°, along with fatigue and stiffness in some athletes. These results support longitudinal monitoring frameworks integrating strength, mobility and load management. A personalised approach is essential to preserve performance and reduce shoulder overload risk.