Shoulder Overuse Injury History Is Associated With Imbalanced Strength Functional Ratio and Bilateral Asymmetry in...

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.

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 nondominant 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 mos before testing were reported.

No injury was surveyed in able-bodied athletes while nine dominant shoulder overuse injuries were reported in nine 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).

External rotator muscle conditioning should be implemented in overhead para athlete regular training to alleviate shoulder imbalance and bilateral asymmetry, especially in fatigued conditions.