Asymmetry in glenohumeral muscle strength of sitting volleyball players : an isokinetic profile of shoulder rotations strength

Sitting volleyball (SV) is a popular Paralympic game, in which shoulders of SV players are overloaded continuously during play. Nevertheless, shoulder girdle muscle function has never been measured in this population yet. The objective of this study was to investigate the dominant and non-dominant strength profile of male and female elite SV players on a glenohumeral level. A total of 13 Brazilian SV national team players volunteered to participate in this study (male: N.=6, age 32.8±4.1 years, body mass 83.2±19.4 kg, seated height 1.47±0.04 m; female: N.=7, age 32.8±4.1 years, body mass 80.1±17.9 kg, seated height 1.36±0.05 m). A Biodex dynamometer was used to measure internal rotation (IR) and external rotation (ER) of the glenohumeral muscle strength at 60°/s and 180°/s velocities in a concentric/concentric mode.It was observed that male SV players were stronger than the female players at both upper limbs. Concerning the side effects, significant differences were found for IR at 60°/s velocity (F=7.55, P=0.02) and ER at 180°/s velocity (F=5.91, P=0.03), with higher values on the dominant limb in comparison to the non-dominant limb for both the male and female players. There were significant gender differences for the IR inter-limb asymmetry at 180°/s velocity, with a greater asymmetry between both shoulders in the male players compared to the female players, preference for the dominant side in both groups. The SV players have an asymmetrical rotational strength profile. As muscular imbalance is a common injury pattern among overhead players. The findings of this study may assist the SV coaches and physiotherapists for evaluation and training of strength of the ER and IR shoulders of these players60339540