How to Stretch Your Calf Muscles
Elastic, flexible calf muscles can soften the shock at the first point of impact--your foot and ankle region

Gastrocnemius (outer calf): Sit with both legs straight. Loop a rope around the ball of one foot and grasp each end of the rope. Flex your foot back toward your ankle, toes toward your knee.

Soleus (inner calf): Sit with one leg straight and the other bent. Grasp the bottom of the foot on the bent leg. Keeping your heel on the ground, pull your foot toward your body as far as you can.

Achilles Tendon (attaches heel to calf): Sit with one leg straight and one bent. Bring your heel close to your buttocks. Keeping your heel on the ground, pull your foot toward your body.