Why is Achilles pain common in runners?
Achilles pain is very common for recreational and competitive runners. Studies show that as much as 10% of runners will experience some form of Achilles pain annually. It can be an extremely nagging issue that hinders enjoyment for recreational runners and performance for competitive runners. So why is it so common?
Anatomy involved with the Achilles tendon
Let’s start with a look at the anatomy. There are three muscles that make up the calf: the gastrocnemius (outer layer of the calf), soleus (inner layer of the calf), and plantaris (a long, but small muscle in the inner layer). The gastrocnemius and soleus are the bigger of the three muscles and insert into the Achilles tendon, which attaches to the calcaneous, or heel bone. When the calf muscles contract--or shorten--they pull up on the Achilles tendon which, in turn, pulls up on the calcaneous. This muscle-tendon-bone pulley system causes the foot to flex downward, like when doing a calf raise exercise.
When the calf muscle contracts repetitively at a high force, like in running, it causes strain on the Achilles tendon. Like muscles, tendons can strengthen with appropriate loading exercise. This loading exercise causes micro-trauma to the tendon and with adequate rest time and nutrition the body will repair the tendon stronger than before. Excessive micro-trauma, however, can lead to inflammation and degeneration of the tendon. This results in pain and usually a thickening of the Achilles tendon which can occur at the back portion of the heel or several inches up from the heel. When this occurs it is called Achilles tendinopathy.
For nearly all runners Achilles tendinopathy is an overuse injury, the result of adding excessive mileage or speed to a training regimen. Tendinopathy is common because many runners are often pushing the limits of what their Achilles can handle. For professional runners this may mean increasing from 80 to 100 miles a week at six minute mile pace. For recreational runners tendinopathy could occur by adding an extra running day to a weekly regimen or adding three miles to a normal run.
With rest or limiting mileage some runners can get over Achilles pain with days or a few weeks. For others Achilles tendinopathy can become chronic and last for months. As many runners know when this occurs it can be very frustrating. There are recommended treatments to try when this does happen.
Tendon loading through progressive strengthening exercise is typically the treatment to try because it is effective and can be done easily at home. This type of strengthening may be done with slow calf raises while standing on one or two legs, or by eccentrically loading the calf. Setting up a strengthening plan may be best accomplished with assistance from a physical therapist to determine the intensity and duration of exercise. Other treatments that may be recommended for a stubborn Achilles tedinopathy may include extracorporeal shockwave therapy, certain types of injections, or placement of nitroglycerin patches over the tendon; these treatments are typically done by physicians.
If you are a runner who has struggled with Achilles pain know that you are not alone! In a lifetime of running most people will experience some sort of Achilles pain. Luckily Achilles tendinopathy is treatable and most people return to pain-free running within several months.