Hamstring strain injuries frequently occur during high‐speed running, when muscle tension is markedly increased. Given the viscoelastic properties of muscle, stress during elongation is expected to be velocity‐dependent. Therefore, this study investigated the effect of elongation velocity on the stress in individual hamstring muscles. Seven Thiel‐embalmed cadaveric lower limbs were used to isolate the biceps femoris long head, semimembranosus, and semitendinosus muscles. Specimens were fixed to a testing apparatus and passively elongated to 10% strain at five elongation velocities (20–300 mm/min), while tensile load and displacement were recorded. Muscle cross‐sectional area was measured using ultrasound to calculate stress. A two‐way repeated‐measures analysis of variance examined the effects of muscle and velocity on stress at 10% strain. The results revealed no significant interaction between muscle and velocity ( p > 0.05); however, both velocity and muscle had significant main effects on stress ( p < 0.001). Post hoc analysis indicated that stress increased significantly with velocity (20 mm/min: 44.6 kPa, 50 mm/min: 47.4 kPa, 100 mm/min: 50.8 kPa, 200 mm/min: 56.4 kPa, 300 mm/min: 61.1 kPa). These findings suggest that stress in the hamstring muscles increases with elongation velocity, which may contribute to the risk of strain injuries during high‐speed running. However, the results should be interpreted in the context of cadaveric testing and elongation velocities that are substantially lower than those observed in vivo.
Nakao et al. (Thu,) studied this question.