Abstract:
"Musculotendon variability influences tissue strains experienced by the biceps femoris long head muscle during high-speed running"
The hamstring muscles frequently suffer injury during high-speed running, though the biomechanical factors that make an individual more susceptible to injury remain poorly understood. This study aimed to measure the musculotendon dimensions of the biceps femoris long head (BFlh) muscle, the hamstring muscle most often injured, and to use sophisticated computational models to assess the influence of variability in the BFlh's dimensions on internal tissue strains during high-speed running. High-resolution magnetic resonance (MR) images were acquired over the thigh in 12 collegiate athletes, and musculotendon dimensions were meticulously measured in the proximal free tendon/aponeurosis, muscle, and distal free tendon/aponeurosis. Finite element meshes were generated based on the average, standard deviation, and range of BFlh dimensions, with simulation boundary conditions defined to match muscle activation and musculotendon length change in the BFlh during high-speed running. The research revealed that muscle and connective tissue dimensions varied significantly between subjects, with a coefficient of variation (CV) of 17±6% across all dimensions. For all biomechanical simulations, peak local strain was consistently highest along the proximal myotendinous junction, which is where injury typically occurs. Model variations demonstrated that peak local tissue strain increased as the proximal aponeurosis width narrowed and the muscle width widened. These findings from the aponeurosis width and muscle width variation models clearly indicate that the relative dimensions of these structures biomechanically influence internal muscle tissue strains. The results of this study strongly suggest that a musculotendon unit's architecture profoundly influences its strain injury susceptibility during high-speed running
