Muscular activity pattern during sprint running

Abstract

The muscular activity pattern, function and maximal contraction velocity during the starting dash and sprint running at maximal velocity were studied, The subjects were five adult male sprinters , whose sprint running moyements in the sagittal plain were analyzecl (100 fps) from videotape recordings made with a high-speed camera, The ground reaction forces and EMGs of eight leg muscles were also recorded, Changes in length from the origin to the insenion (muscle-tendon complex: MTC) of the eight leg muscles were calculated using several methods reported by Grieve et al, (The muscular activity pattern and the maximal contraction velocity were investigated from the change in length of the MTC when the EMG activity was observed, The turnover velocity of the muscular activity pattern in the stretch-shortening cycle (SSC) was calculated from the acceleration of the contraction. Also the hip, knee and ankle joint torqges were calculated, and the following results were obtained. 1. Changes in muscular activity pattern and maximal contraction velocity during the starting dash During the first half of the swing period, the m. gluteus maximus exhibited shortening activity, the m. rectus femoris exhibited stretching activity and the m, iliopsoas exhibited SSC muscular activity , The m. vastus lateralis exhibited shortening activity during the last half of the swing period and stretching activity during the first haff of the foot cQntact period, The m. bigeps femoris exhibited SSC muscular activity from the middle of the swing period to the middle of the foot contact period. The m. gastrocnemius and m. soleus exhibited SSC muscular actiyity during the foot contact periodi. Above al1, the maximal shortening and stretching velocity, and the turnover velocity increased with increasing sprint mmning yelocity after the start, except for the shortening yelocity of the m. gastroc-nemius and m, soleus, and the stretching velocity of the m, vastus lateralis, whose contraction velocity stayed almost constant. 2. Muscular activity and function during sprint running at maximal velocity During the first half of the swing period, the m. rectus femoris produced knee extension torque by stretching activity which functioned to reduce the knee flexion force which occurred through the joint fDrce related to hip fiexion torque. During the latter haif of the swing period, knee flexion torque developed as a by-product from the m. biceps femoris, which serves as a hip extensor. On the other hand, the knee extension force which occurred through the joint force related to hip extension torque, the momentum required to extend the knee joint, and the knee extension torque which was produced by the shortening activity of the m. vastus lateralis were observed during the same period, Therefore, ' the knee extension movement observed from the outside occurred as a result of the total of these tcwrtsffx*rt#Etse*Mverv +590-0496 fcwakMMaseefyeqnN1558-1Graduate school ofHlaalth and Spart Sct'ences, ()saha [htiversity of HcaIth and Spart Sbiences, 1558-1 Nbda, Kumaton:cho, imnan-gun, Clsaha 59CL-C)496