Altered Hamstring Mechanics and Strength Deficits Impair Balance Control in Athletes Following Hamstring Strain

Hamstring strains result in alterations to muscle function; however, evidence regarding how these changes affect balance performance remains limited. This study investigated the impact of altered hamstring function on balance control in athletes with hamstring injuries. Thirty-two participants (16 injured hamstrings and 16 controls) participated in this study. Hamstring properties and strength were assessed to evaluate muscle function. Participants performed maximum lean forward in both single- and double-leg stances under eyes-closed and eyes-open conditions on a force platform. Then, the center of pressure was analyzed. Injured athletes exhibited higher hamstring stiffness (P = .028) and decrement (P = .019), and lower strength (P = .024 at 0° and P = .005 at 90°). Also, they displayed a greater sway range in both the anteroposterior (P = .029) and mediolateral directions (P = .030), together with increased center of pressure velocity (P = .019) and a larger sway area (P = .020) during a forward lean task under eye-closed conditions. Significant associations were identified between hamstring function and balance control. These findings indicate that alterations in hamstring function following muscle strains contribute to impaired balance control. This factor should be considered in training and rehabilitation for athletes recovering from hamstring injuries.