When they contract, they pull on the achilles tendon causing your foot to point down and helping you raise up on your toes. This powerful muscle group helps when you sprint, jump, or climb. Tendocalcaneal Bursitis - A bursa is a fluid filled sac designed to limit friction between rubbing parts. These sacs, or bursae, are found in many places in the body. When a bursa becomes inflamed it is called a bursitis.
Tendocalcaneal bursitis is an inflammation in the bursa behind the heel bone.
This bursa limits friction where the thick fibrous achilles tendon that runs down the back of the calf glides up and down behind the heel. This can happen during a strong contraction of the muscle, as when running or sprinting. Landing on the ground after a jump can force the foot upward, also causing injury. The strain can affect different portions of the muscles or tendon. For instance, the strain may occur in the belly of the muscle.