Originally Posted by Chas Tennis
"The gastroc tends to be the primary plantarflexor of the ankle" - that depends largely on the angle of the knee joint.
I believe for the most of the time during tennis play the knee is bent. Do we agree that the Soleus is then involved but that the Gastrocnemius is not? (Since the Gastrocnemius attaches above the knee it goes slack as the knee becomes bent.)
Yes, as the angle of the knee enters more flexion, you'll get more soleus involvement, but it's not like the gastroc totally goes on vacation.
The gastroc is a secondary knee FLEXOR, so as the knee is bent, it's contracted, not on slack.
Playing tennis, the brain wants "all hands on deck" so to speak in terms of muscle recruitment; add the violent eccentric/concentric contractions of the muscles plus the amount of force impacted during running/stopping/split step and you can see how easily spasms/pain can occur.