A comparison of electrical activity in the triceps surae at maximum isometric contraction with the knee and ankle at various angles

Publisher Website
Google Scholar
Abstract
The purpose of this study was to test the endurance of the soleus muscle, and to examine the joint position at which it is most active, while simultaneously suppressing the activity of the gastrocnemius. Ten young males performed maximum isometric contraction of the triceps surae for 100 s, and the endurance and plantar flexion torque of this muscle were measured at various angles of the knee and ankle joints. The electromyogram was measured simultaneously and subsequently converted into integrated electromyogram (IEMG) values. With the knee flexed at 130°, the rate of change in IEMG values for the soleus (0.454% · s−1) with the ankle in a neutral position was significantly higher than that for the medial and lateral gastrocnemius. Both with the ankle dorsiflexed at 10° and in the neutral position, the rate of change in IEMG for the soleus was significantly higher with the knee flexed at 90° and 130° than with the knee fully extended. With the knee flexed at 90° and 130°, the IEMG activity of the soleus during the initial (5–10 s) and final 5 s tended to be higher than those for the medial and lateral gastrocnemius, regardless of the ankle joint position. We conclude that the position in which the soleus acts most selectively during a sustained maximum isometric contraction of the triceps surae is with the ankle in a neutral position and the knee flexed at 130°.

This publication has 0 references indexed in Scilit: