Muscle and Function: The Gastrocnemius
The Gastrocnemius is a bipennate muscle that originates on the lateral and medial condyles of the femur. It runs down the back of the leg and invests into the Achilles tendon and inserts into the calcaneus. It is the most superficial muscle of the lower leg.
Because it crosses two joints, it has two functions. At the ankle joint, the gastrocnemius pulls the toes down (plantar flexion). At the knee joint, it aids in knee flexion and preventing hyperextension of the knee joint.
It is most active during running and jumping most likely due it’s having a higher percentage of fast twitch muscle fibers.
The best method for strengthening it is a toe raise (with or with out weight) from a straight-legged position. Bending the knee and doing a toe raise will almost completely inactivate the gastrocnemius.