The Achilles tendon is the largest and most vulnerable tendon in the body. It joins the gastrocnemius (calf) and the soleus muscles of the lower leg to heel of the foot. The gastrocnemius muscle crosses the knee, the ankle, and the subtalar joints and can create stress and tension in the Achilles tendon. Tendons are strong, but not very flexible so they can only so far before they get inflammed and tear or rupture.

Causes of Achilles Tendonitis
Achilles tendonitis is a chronic injury that occurs primarily from overuse. It tends to come on gradually over time until pain is constant and exercise or activity too painful to continue. The biggest cause of chronic Achilles tendonitis is ignoring early warning signs and pushing through pain. If the Achilles tendon is sore, or aches, you need to pay attention and rest it immediately.

Another major contributor in the development of Achilles tendonitis is tight of weak calf muscles. If this muscle is weak and becomes fatigued, it will tighten and shorten. Overuse also causes muscle fatigue. The bottom line with Achilles tendonitis is that the more fatigued the calf muscles are (regardless if it is from weakness or overuse), the shorter and tighter they will become. This tightness increases the stress on the Achilles tendon, and a tendonitis can develop. Sudden increases in training, hill running or a lot of speedwork can also lead to Achilles tendonitis.

Treatment
At the first sign of Achilles tendon pain, cut back and reduce your training. Stop speed training and hill running, and begin gentle calf stretching after exercise when the muscle and tendon is still warm and flexible. Post-exercise ice may also help. Be carful to avoid excessive stretching that could aggravate the problem. Strengthening the calf muscle can help reduce the stress on the Achilles tendon. Toe raises, and balancing on your toes, and wall stretching are useful exercises.

It is not necessary to stop activity completely (you may consider cross training) as long as you pay attention to muscle soreness and reduce activity accordingly.