出版社：Japan Society of Physical Education, Health and Sport Sciences
摘要：This study aimed to investigate the change in length of the triceps surae and the ankle plantar flexion torque produced by it during the first stance from a crouch start. Three male track and field athletes volunteered to participate. The participants sprinted 10 m from starting blocks. The ground reaction forces of the first leg stance were determined using a force platform (1000 Hz). Simultaneously, 3D coordinates were recorded by a motion analysis system (250Hz) using 20 cameras (MX-T20). We developed a musculoskeletal model and searched for the muscle excitation to re-create the motion of the 3 athletes using the optimization method (genetic algorithm). The lengths of the muscle tendon complex (MTC), contractile element (CE), and series elastic element and the ankle plantar flexion torque produced by the triceps surae were calculated during the first stance. The main results were as follows (1) The ankle plantar flexion peak torque produced by the soleus appeared at 70% normalized time (0%: ground contact; 100%: toe off). From the 70% normalized time, the ankle plantar flexion torque produced by the soleus decreased considerably. (2) The ankle plantar flexion peak torque produced by the gastrocnemius appeared at the 75% normalized time. From the 80% normalized time, the ankle plantar flexion torque produced by the gastrocnemius was larger than that produced by the soleus. (3) The CE of the soleus continued to shorten during the first stance. (4) From the 20% to 40% normalized time, the CE of the gastrocnemius continued to lengthen. At other points, the CE of the gastrocnemius shortened. These findings suggest that the ankle plantar flexion torques produced by the soleus and gastrocnemius differ in pattern, as the soleus contracts concentrically during the first stance and the gastrocnemius contracts eccentrically from 20% to 40% normalized time but concentrically at other points.
