Biomechanical properties of muscle-tendon unit under fast passive stretch

This paper presents a new procedure to evaluate the injury mechanism of muscle-tendon unit. This preliminary study used an impactor with variable mass that dropped freely from a height of 50 cm to impact one end of a lever; this lever jig could immediately change compression energy to traction energy. The traction force history of the specimen was recorded during the traction. At the same time a high-speed camera recorded the stretch event. The results showed that a muscle-tendon unit has a highly nonlinear mechanical behaviour. Muscle fibers reached their maximum stretch force and completed failure step by step. This effect is important as the ability of muscles to function as energy absorbers can prevent rupture entirely to themselves at any one time and can protect bones and joins.