RESUMO
Background: We aimed to analyze the range of motion [ROM] and internal rotation [IR] and external rotation [ER] isokinetic strength according to humeral retroversion of the dominant shoulder
Methods: We included 40 elite baseball players in Korea [OBP group: n=20 players with careers spanning >10 years, age: 19.37+/-2.21 years, height: 181.00+/-5.41 cm, weight: 84.58+/-7.85 kg; BBP group: n=20 players with careers spanning <10 years, age: 16.55+/-1.36 years, height: 177.27+/-7.57 cm, weight: 77.27+/-8.14 kg]. Radiography was performed to examine humeral retroversion, a goniometer was used to measure IROM and EROM, and a dynamometer was used to measure IR and ER isokinetic strength [speed set at 180°/s or 300°/s]
Results: The BBP and OBP groups had significantly different IR and ER isokinetic strength [180°/s and 300°/s] [P<0.001] and dominant shoulder retroversion [P=0.009]. In the BBP group, retroversion had no correlation with ROM and with IR or ER isokinetic strength [180°/s and 300°/s]. In the OBP group, retroversion had no correlation with ROM and with ER isokinetic strength at 180°/s, but had significant correlation with IR isokinetic strength at both 180°/s [r=0.483, P=0.007] and 300°/s [r=0.373, P=0.043] and ER isokinetic strength at 300°/s [r=0.366, P=0.046]
Conclusion: Thus, youth players with careers spanning >10 years had significantly higher humeral retroversion, IROM, EROM, and IR and ER isokinetic strength of the dominant shoulder than youth players with careers spanning <10 years. Furthermore, humeral retroversion and ROM were not significantly related, but IR and ER isokinetic strength were significantly positively related with retroversion in both groups