Shoulder overuse injury history is associated with imbalanced strength functional ratio and bilateral asymmetry in overhead male Para athletes in resting and fatigued conditions.

Objective: The present study aimed to compare shoulder functional ratio and bilateral strength asymmetry between overhead Para athletes and able-bodied peers, and ascertain whether those factors could be associated with shoulder injury history in Para athletes under resting and fatigued conditions.

Design: Sixteen sitting volleyball Para athletes and 12 able-bodied volleyball players were evaluated. The shoulder functional ratio was measured at rest and after a fatiguing shoulder internal-external rotation exercise on dominant and non-dominant shoulders. Imbalanced muscle strength profiles were identified as a functional ratio < 0.7 and bilateral peak torque asymmetry either >10% or > 15%. All injuries incurred over the past 2-months prior testing were reported.

Results: No injury was surveyed in able-bodied athletes while 9 dominant shoulder overuse injuries were reported in 9 Para athletes. Functional ratio and bilateral asymmetry were not significantly different between groups at rest or after exercise in either shoulder(p > 0.05). Functional ratio < 0.7 and bilateral asymmetry of either >10% or > 15% were statistically associated with shoulder overuse injury history in the dominant limb in Para athletes(p < 0.05), but with a higher relative risk under fatiguing-conditions(p < 0.01).

Conclusion: External rotator muscle conditionning should be implemented in overhead Para athlete regular training to alleviate shoulder imbalance and bilateral asymmetry, especially in fatigued conditions.