Output of skeletal muscle contractions. a study of isokinetic plantar flexion in athletes

Abstract

Maximum torques, total work and mean power of isokinetic plantar flexions were measured with simultaneous registrations. The integrated electromyograms (iEMG) were obtained by surface electrodes from all three heads of the m. triceps surae. The method applied offers possibilities for adequate description of dynamic muscular work which in the case of plantar flexion in trained man declines as a negative exponential function of angular motion velocity. The decline is parallel to that of maximum torques. The summed triceps surae iEMG was inversely proportional to the velocity and direct proportional to time suggesting that structural rather than neural factors determine the relationships between velocity of angular motion and maximum torque/total work of single Mmaneuvers. Moreover, the fact that maximum mean power as well as maximum electrical efficiency were reached at the functional velocity of toe-off during gait suggests an influence of pragmatic demands on plantar flexion mechanical output.