According to the Greek myth, Achilles was vulnerable only at his heel. It's a trait that he must have passed down to all other humans when he gave his name to the Achilles tendon, which connects the calf muscles to the heel bone.

The Achilles tendon is the largest tendon in the human body and can withstand forces of 1,000 pounds or more. But it is also the most frequently ruptured tendon, and both professional and weekend athletes can suffer from Achilles tendonitis, a common overuse injury and inflammation of the tendon.

Any number of events may trigger an attack of Achilles tendonitis, including:

• Rapidly increasing your running mileage or speed
• Adding hill running or stair climbing to your training routine
• Starting up too quickly after a layoff
• Trauma caused by sudden and/or hard contraction of the calf muscles when putting out extra effort such as in a final sprint
• Overuse resulting from the natural lack of flexibility in the calf muscles

Symptoms of Achilles tendonitis fall into a common pattern.

• Mild pain after exercise or running that gradually worsens
• A noticeable sense of sluggishness in your leg
• Episodes of diffuse or localized pain, sometimes severe, along the tendon during or a few hours after running
• Morning tenderness about an inch and a half above the point where the Achilles tendon is attached to the heel bone
• Stiffness that generally diminishes as the tendon warms up with use
• Some swelling

Because several conditions, such as a partial tendon tear and heel bursitis have similar symptoms, you need to see your orthopaedic surgeon for a proper diagnosis.

You may not be able to prevent Achilles tendonitis, but here are six steps to reduce your risk of incurring an attack:

• Choose your running shoes carefully. They should provide sufficient cushion for the heel strike. Using a prescribed orthotic to change the position of a poorly aligned heel bone may also help. Perhaps the best precaution is to know your limits and to follow a sensible program when you exercise.
• Walk and stretch to warm up gradually before running. It's better to spend few minutes warming up than to spend months on the sidelines with a ruptured Achilles tendon.
• Focus on stretching and strengthening the muscles in the calf.
• Increase your running distance and your speed gradually, in increments no greater than 10% a week.
• Avoid unaccustomed strenuous sprinting, hill running and the like.
• Cool down properly after exercise.