Achilles Tendinitis

Accounting for about 10 percent of all running injuries, Achilles tendinitis is an acute inflammation of the Achilles tendon that runs along the back of the ankle, attaching the calf to the heel bone. It’s also the strongest tendon in the body—when healthy. When unhealthy, it can result in sharp pain that makes running impossible. (Note: If the pain lasts for more than a few weeks, it’s not really tendinitis anymore, but has elevated its status.) Some argue that the injury should really be called Achilles tendinopathy, because the problem is inflammation around the tendon, while the tendon itself is simply weak and dysfunctional. Regardless of how it is classified, the end result is pain in the affected area, which can be resolved with acute treatment of the general inflammation and then rehabilitation of the tendon.

Achilles Tendinitis
Achilles tendinitis is an acute inflammation of the Achilles tendon that runs along the back of the ankle, attaching the calf to the heel bone. Illustration: Oliver Baker

Symptoms of Achilles Tendinitis

  • Pain along the Achilles tendon, at the back of the lower leg just above the heel. This is often accompanied by swelling close to the heel.
  • Achilles tendinitis can commonly be confused with other heel injuries. However, if you pinch the Achilles and it’s very sore, then the source of the problem is likely the tendon.

Causes of Achilles Tendinitis

There are a number of things that can lead to Achilles tendinitis. Some of the most common causes are tight calves, foot instability or mechanical flaws such as over striding when you run.

“It’s almost always an overstriding problem,” says Joe Uhan, a physical therapist, coach and ultrarunner. When your foot lands in front of your body, especially if you land on the forefoot, you end up putting all the weight on your Achilles tendon. “That’s stress your body has to absorb.”

If your foot is unstable upon landing, it can twist and stress the tendon. This is particularly true if you land on your forefoot and push off with your toes. Runners who don’t engage their glute muscles may find that they end up running on their toes and using more force in their push-off, which all puts pressure on the Achilles.

During the push-off phase of running, the Achilles is exposed to a force that is more than seven times your body weight. This means anything that puts repeated stress on the Achilles tendon can lead to Achilles tendinitis. It is also more likely to occur if a runner is prone to Achilles problems. Other contributors include too much mileage, too many hill repeats or too much speed work without a proper build-up. It’s particularly common after quick increases in training volume or intensity.

In fact, there isn’t always an obvious reason why someone might start to suffer from Achilles tendinitis. “Most patients usually don’t have any identifiable source,” says Phinit Phisitkul, a University of Iowa associate professor in orthopedic surgery.

Achilles Tendinitis Treatment

Once you have sharp pain along your Achilles tendon, the immediate treatment is obvious and simple: rest, ice and anti-inflammatories. You may also want to sleep with a brace on your foot. Runners with Achilles tendinitis should avoid walking barefoot or in high heels in order to keep the tendon from over-stretching or shortening. Depending on the severity of the injury, especially because blood supply is so low to that area, it can take a long time to heal and recover—often a minimum of four to six weeks.

Mobilizing the tissue using a foam roller or other tool that helps with self-massage can be particularly helpful. Focus on finding specific trigger points and roll them with firm pressure to loosen the area.

After resolving the acute pain, studies have found some of the most successful Achilles tendinitis treatments involve eccentric strengthening exercises. If your pain is severe, you may want to continue to rest before attempting strengthening work or workouts. Runners should ease back into exercise and avoid speed work for at least a couple of weeks.

Try this exercise, which is the opposite of a calf raise, when you’re ready. Gradually lower your heel from a raised position on a step and then use the healthy leg to raise it back to the starting position, being sure not to stress the tendon in the rising motion. Do 15 repetitions, twice a day.

If you find that Achilles pain is a recurring condition, consider consulting a professional who analyzes running mechanics to determine what might be causing stress to your Achilles. 

Prevention of Achilles Tendinitis

When people experience Achilles tendinitis, it often starts as stiffness in the Achilles tendon. If you take steps to increase flexibility, strengthen the ankle and decrease stress on the tendon at the first sign of stiffness, it’s possible to prevent the problem from escalating.

One of the easiest ways to prevent Achilles tendinitis is this simple stretch that keeps the tendon strong and flexible. Stand with one foot behind the other as you push against the wall. Do this for a few minutes every day. However, be sure not to over stretch the tendon, since an over-flexible tendon is a leading predictor of Achilles tendinitis.

It can also be highly beneficial to do eccentric strengthening exercises to ensure the tendon doesn’t weaken or deteriorate. Eccentric strengthening includes calf raises, single-leg deadlifts, single-leg squats and box jumps.

Other Common Running Injuries

How To Beat Achilles Tendinitis

Kelly O'Mara / March 18, 2014

This nagging injury can be long-lasting if not treated — and if your running form needs some work.

Med Tent: Getting Over Achilles Tendinitis

Jordan Metzl, M.D. / May 2, 2012

Dr. Jordan Metzl discusses what causes an aching Achilles tendon and offers advice for getting over an injury to this area of the body.