Endurance time in slow and fast contracting muscle groups

Abstract

The endurance time (the maximum duration of a sustained isometric muscle contraction) of a slow and fast contracting muscle group was investigated in six subjects. The muscle groups examined were the plantar and the dorsal flexors of the ankle joint. The measurements were made with a 90° flexion in the knee joint. After determination of the maximum isometric muscle strength, the endurance time was measured at 50% of the maximum strength. The plantar flexors showed a statistically significant longer endurance time than did the dorsal flexors. This indicates that the ability of a muscle group to maintain a sustained isometric contraction depends on the relative proportion of slow and fast contracting muscle fibers.