Derived from the Greek words for stomach and leg, gastrocnemius refers to the ‘bulge’ of the calf and is in fact just half of that structure, otherwise paired with the soleus muscle. On its own, gastrocnemius is an extremely powerful bipennate, made up of white, type II fibers (fast twitch) and located at the rear area of the lower leg, where it runs from its twin heads atop the knee down to the heel. Rising up from the Achilles tendon on the posterior section of the heel bone, gastrocnemius extends via its lateral and medial heads to the femur’s lateral and medial condyles.
Running, jumping, and other similar explosive actions owe their power to Gastrocnemius. Flexing the leg at the knee joint and the foot at the ankle, traction is created on the femur which pulls it towards the tibia and causes the knee to bend.