The Achilles tendon is the largest tendon in the human body and can withstand forces of 1,000 pounds or more. It also is the most frequently ruptured tendon, usually as a result of a sports injury. Both professional and weekend athletes may suffer from Achilles tendonitis, a common overuse injury and inflammation of the tendon.
What is Tendonitis?
Achilles tendonitis is an inflammation of the Achilles tendon. This inflammation is typically short-lived. Over time, if not resolved, the condition may progress to a degeneration of the tendon (Achilles tendonosis), in which the tendon loses its organized structure and is likely to develop microscopic tears. Sometimes the degeneration involves the site where the Achilles tendon attaches to the heel bone. In rare cases, chronic degeneration with or without pain may result in rupture of the tendon.
As “overuse” disorders, Achilles tendonitis and tendonosis are usually caused by a sudden increase of a repetitive activity involving the Achilles tendon. Such activity puts too much stress on the tendon too quickly, leading to micro-injury of the tendon fibers. Due to this ongoing stress on the tendon, the body is unable to repair the injured tissue. The structure of the tendon is then altered, resulting in continued pain.
Athletes are at high risk for developing disorders of the Achilles tendon. Achilles tendonitis and tendonosis are also common in individuals whose work puts stress on their ankles and feet, such as laborers, as well as in “weekend warriors”—those who are less conditioned and participate in athletics only on weekends or infrequently.
In addition, people with excessive pronation (flattening of the arch) have a tendency to develop Achilles tendonitis and tendonosis due to the greater demands placed on the tendon when walking. If these individuals wear shoes without adequate stability, their over-pronation could further aggravate the Achilles tendon.
Events that can cause Achilles tendonitis may include:
- Hill running or stair climbing.
- Overuse, stemming from the natural lack of flexibility in the calf muscles.
- Rapidly increasing mileage or speed when walking, jogging, or running.
- Starting up too quickly after a layoff in exercise or sports activity, without adequately stretching and warming up the foot.
- Trauma caused by sudden and/or hard contraction of the calf muscles when putting out extra effort, such as in a sprint.
- Improper footwear and/or a tendency toward overpronation.
Symptoms of Foot Tendonitis
The symptoms associated with Achilles tendonitis and tendonosis include:
- Recurring 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.
- Sluggishness in your leg.
- Mild or severe swelling.
- Stiffness that generally diminishes as the tendon warms up with use.