Potential mechanisms of hamstring strain injuries during sprinting acceleration phase in soccer players: A biomechanical investigation

Sprinting is the most common activity associated with hamstring strain injuries in soccer. However, the potential mechanisms for hamstring strain injuries during the acceleration phase of sprinting are unclear. Therefore, this study aimed to characterize these elements in soccer players and define the potential mechanism of hamstring strain injury. Ten male soccer players with no lower-limb injuries in the past year were recruited for this study. Each participant was instructed to perform a minimum of three successful 15 m sprints. Hamstring kinematics and activations were estimated by employing musculoskeletal modeling and wireless electromyography to define potential injury mechanisms. During the acceleration phase, the hamstring muscles undergo great strain and high activation levels during the late swing and early stance phases. The hamstring muscles experienced overloading during the foot strike of the running gait cycle. Additionally, the biceps femoris long head was significantly more stretched than the semimembranosus and semitendinosus (p < 0.01, p < 0.05). Based on these results, hamstring injuries are likely to occur during the late-swing and initial stance of the running gait cycle, with the biceps femoris long head being more susceptible to injuries than other hamstring muscles.