Asymmetry of dominant and non-dominant shoulders in university level men and women volleyball players

Abstract

Purpose. Volleyball involves repetitive forceful actions predominantly of one arm, which could eventually lead to an injury or shoulder pathology. the aim of the study was to compare the range of motion and strength in the dominant and non-dominant shoulders of university level volleyball players, with the objective of examining any differences between sexes. Methods. A total of 19 university level volleyball players (9 men: 81.3 ± 8.0 kg, 21 ± 1 years; 10 women: 66.0 ± 8.2 kg, 19 ± 1 years) participated. the passive internal and external range of motion of the dominant and non-dominant spiking shoulders were measured with a goniometer. the shoulder strength tests were performed on an isokinetic dynamometer at the speed of 60°/s in the concentric mode of contraction. Shoulder internal and external rotator concentric strength, range of motion, and internal/external rotation strength ratios were tested between arm dominance and sex with the use of 2-way mixed design ANOVA. Results. Internal and external rotation strength was asymmetrical in both men and women, in favour of the dominant side (p < 0.05). both men and women displayed asymmetrical external/internal ratios (p < 0.05), with greater ratios present in the non-dominant side. Conclusions. University level men and women volleyball players exhibit similar levels of significant asymmetry in the internal/external rotation strength between dominant and non-dominant spiking arms. Furthermore, subject-specific responses in strength asymmetries suggest further investigation at the individual level. Isokinetic shoulder screening could be used to reveal information about possible risk factors for shoulder injuries.