The Achilles tendon is the lower part of the calf muscle that attaches through a dovetail-like insertion into the heel bone. This tendon is commonly strained, especially in young adults, due to poor stretching before vigorous exercise. It is most commonly strained when playing hardcourt games such as squash or tennis and can be extremely painful.
The Achilles tendon can split due to excessive contraction of the calf muscle. This most commonly occurs if the tendon is not stretched before activity, if the body is dehydrated or if the calf muscle is swollen.