Association Between Hamstring Flexibility And Throwing Shoulder Total Range Of Motion In Adolescent Baseball Players

The overhead throwing motion is complex and restricted hamstring range of motion (ROM) may place additional stress on the throwing shoulder and increase the risk of injury. However, the relationship between the contralateral hamstring flexibility and throwing shoulder total ROM in adolescent baseball players is unknown. PURPOSE: To determine the association(s) between the contralateral hamstring-popliteal angle and total throwing shoulder ROM in high school baseball players. METHODS: 14 high school varsity baseball players volunteered for this study. Inclusion criteria included high school aged males on the varsity baseball team. Exclusion criteria included current leg or arm injuries. Each athlete played 5 times a week and played different positions. Hamstring and total throwing shoulder ROMs were measured using a goniometer by the same examiner. 3 examiners determined maximum ROM by joint end feel to ensure quality control. Contralateral hamstring flexibility was measured using the popliteal angle test. These measurements were compared to the total throwing shoulder ROM using a linear regression analysis. RESULTS: The correlation coefficient, r, was + 0.3928, indicating a moderate positive linear relationship. We conclude that higher contralateral hamstring-popliteal angles may cause a compensatory increase in throwing shoulder total ROM, which may increase the risk for shoulder injuries. CONCLUSION: Overhead throwing athletes with limited hamstring flexibility should be counseled appropriately regarding their risk for shoulder injury. Baseball players should improve their hamstring flexibility to reduce throwing shoulder overcompensation. Additional research with a larger sample size is encouraged to further establish the association between contralateral hamstring flexibility and throwing shoulder total ROM. We highlight the role hamstring inflexibility may play in shoulder injury development in adolescent baseball players.