Bilateral comparison of shoulder range of motion and peak isometric strength in amateur tennis players

Lower values of shoulder internal rotation range of motion (ROM-IR) and external/ internal rotation strength ratio (S-ER/S-IR) of the dominant arm (racket grip) compared to the non-dominant arm have been observed in professional tennis players. It is considered that these adaptations could increase the risk of shoulder injury. Little is known about these adaptations in amateur tennis players. The aim of this study was to bilaterally compare the range of motion (ROM) and peak isometric strength (S) of shoulder rotation movements in amateur tennis players (dominant arm [DA] versus non-dominant arm [NDA]). In thirteen amateur tennis players (18-45 years old) the passive ROM and the S of internal rotation (IR) and external rotation (ER) were measured from the supine position, 90(degrees) of shoulder abduction and 90(degrees) of elbow flexion. DA and NDA values were compared by paired samples T-test. DA had lower ROM-IR (t = -9.053; p < .001; d = -2.551) and total ROM-(t = -4.429; p < .001; d = -1.228) compared to NDA (Delta ROM-IR = 23.73 %; Delta ROM-total = 8.32 %). Greater DA S-IR was also detected compared to NDA (t = 2.344, p = .037, d = .650, Delta S-IR = 9.67 %). These results indicate the existence of unilateral adaptations of the shoulder, which have been identified in other publications as risk factors for injury. In contrast to observations in professional tennis players in other studies, no S-related injury risk indicators were found.