To isolate soleus during plantarflexion MMT, what knee position should be used?

To isolate soleus during plantarflexion MMT, what knee position should be used?

• A. Knee flexed
• B. Knee extended
• C. Knee abducted
• D. Knee rotated

Answer: (A)

The ability to isolate the soleus during plantarflexion relies on biasing away the contribution of the gastrocnemius, which crosses both the knee and ankle. When the knee is flexed, the gastrocnemius becomes shortened and its plantarflexion force is minimized, so the soleus—which only crosses the ankle—takes on the work. If the knee were extended, the gastrocnemius would be more able to assist in plantarflexion, making isolation of the soleus harder. Abducting or rotating the knee doesn’t meaningfully change which muscle drives plantarflexion, so those positions won’t isolate the soleus.

The ability to isolate the soleus during plantarflexion relies on biasing away the contribution of the gastrocnemius, which crosses both the knee and ankle. When the knee is flexed, the gastrocnemius becomes shortened and its plantarflexion force is minimized, so the soleus—which only crosses the ankle—takes on the work. If the knee were extended, the gastrocnemius would be more able to assist in plantarflexion, making isolation of the soleus harder. Abducting or rotating the knee doesn’t meaningfully change which muscle drives plantarflexion, so those positions won’t isolate the soleus.