The plantarflexors of the lower limb are often assumed to act as independent actuators, but the validity of this assumption is the subject of considerable debate. This study aims to determine the degree to which passive changes in gastrocnemius muscle length, induced by knee motion, affect the tension in the adjacent soleus muscle. A second aim is to quantify the magnitude of myofascial passive force transmission between gastrocnemius and adjacent soleus. Fifteen healthy volunteers participated. Simultaneous ultrasound images of the gastrocnemius and soleus muscles were obtained during passive knee flexion (0-90 degrees ), while keeping the ankle angle fixed at either 70 or 115 degrees . Image correlation analysis was used to quantify muscle fascicle lengths in both muscles. The data show that the soleus muscle fascicles elongate significantly during gastrocnemius shortening. The approximate change in passive soleus force as a result of the observed change in fascicle length was estimated, and appears to be <5N, but this estimate is sensitive to the assumed slack length of soleus.
AD - 1University of New South Wales. AN - 22723629 BT - Journal of Applied Physiology DA - -35726387164 DP - NLM ET - 2012/06/23 LA - Eng N1 - J Appl Physiol. 2012 Jun 21. N2 -The plantarflexors of the lower limb are often assumed to act as independent actuators, but the validity of this assumption is the subject of considerable debate. This study aims to determine the degree to which passive changes in gastrocnemius muscle length, induced by knee motion, affect the tension in the adjacent soleus muscle. A second aim is to quantify the magnitude of myofascial passive force transmission between gastrocnemius and adjacent soleus. Fifteen healthy volunteers participated. Simultaneous ultrasound images of the gastrocnemius and soleus muscles were obtained during passive knee flexion (0-90 degrees ), while keeping the ankle angle fixed at either 70 or 115 degrees . Image correlation analysis was used to quantify muscle fascicle lengths in both muscles. The data show that the soleus muscle fascicles elongate significantly during gastrocnemius shortening. The approximate change in passive soleus force as a result of the observed change in fascicle length was estimated, and appears to be <5N, but this estimate is sensitive to the assumed slack length of soleus.
PY - 2012 SN - 1522-1601 (Electronic)0161-7567 (Linking) T2 - Journal of Applied Physiology TI - Myofascial force transmission between the human soleus and gastrocnemius muscles during passive knee motion ER -