Comparison of Triceps Surae EMG in Plantar Flexion Test of MMT at Different Knee Angles

Abstract

This study was conducted to examine changes in the muscle activity of the triceps surae, specifically the gastrocnemius and the soleus, depending on the angle of the knee joint during the manual muscle test (MMT) of the plantar flexion of the ankle. The muscle activity of the medial and lateral heads of the gastrocnemius was statistically significantly reduced when the angle of the knee joint was 15°, 30°, and 45° compared to when the angle was 0°. However, there was no statistically significant difference in muscle activity at the angles of 15° and 30° or 45°. There was no statistically significant difference in the muscle activity of the soleus depending on the angle of the knee joint. The ratio of the muscle activity of the soleus to that of the triceps surae showed a statistically significant increase when the angle was 15°, 30° and 45° compared to when the angle was 0°. However, there was no statistically significant difference in muscle activity at the angles of 15° and 30° or 45°. When the angle of the knee joint was 15° or higher during the test of the isolated soleus, the muscle activity of the gastrocnemius was reduced. These results indicate that the angle is suitable for the test of the isolated soleus, but there was no statistically significant difference in the muscle activity of the gastrocnemius when the angle was higher than 15°. Therefore, it can be concluded that the most suitable angle of the knee joint for the isolated MMT test of the soleus is 15°.