Achilles Tendinopathy in Runners
The Achilles tendon acts as a spring when running, transmitting the forces from the ground to the lower leg and vice versa. Due to the repetitive high loads placed on the Achilles during running, the Achilles tendon can become irritated causing pain on the back of the heel. The diagnosis of Achilles tendon pain goes by many different names: Achilles tendinitis, Achilles tendinosis, heel cord pain, etc. For this article, Achilles tendinopathy will be used to describe pain relating to the Achilles tendon.
Cause of Achilles Tendinopathy
The Achilles tendon transfers force from the foot to the calf muscles and vice versa. Since running pus approximately 6 to 8 times body weight through the Achilles tendon, that's a lot of force that is transmitted in this tendon.
Achilles tendinopathy is an overload condition, meaning that the load placed on the tendon has exceeded what it can absorb. There are two different stages of Achilles tendinopathy.
Reactive Achilles Tendinopathy
A reactive tendinopathy occurs after a sudden increase in load on the Achilles tendon. This would normally be a runner who is just starting to run again and has spiked their runner distance or speed. The tendon swells to protect itself from the sudden increase in loading, which is helpful at first but not a long term strategy.
With sufficient rest the swelling inside the tendon decreases and the tendon returns to normal. However, continued loading on the tendon allows swelling to accumulate inside the tendon and separate the tendon fibers.
Degenerative Achilles Tendinopathy
With continued overloading of the Achilles tendon, a degenerative tendinopathy can develop. The swelling in the reactive tendinopathy continues to separate the tendon fibers leading to disorganization and weakening of the Achilles tendon fibers. Although the disorganization and weakening of the tendon fibers is often permanent, new tendon fibers can be built around the old degenerated tendon.
Corticosteroid Injections for Achilles Tendinopathy
As inflammation was once considered the primary mechanism, corticosteroid injections became a popular treatment approach to decrease inflammation in the Achilles tendon. While corticosteroid injections may have a short term benefit in decreasing pain, they may come with a long term consequence.
Research on patellar tendinopathy and tennis elbow (lateral epicondylopathy) have suggested corticosteroid injections may increase the reoccurrence rates. There are also several reports of Achilles tendon ruptures following a corticosteroid injection.
Although these corticosteroid injections may help alleviate pain temporarily, the risk of increase reoccurrence or future tendon rupture questions the use of corticosteroids for tendinopathies.
Treatment of Achilles Tendinopathy
The primary treatment of both a reactive and a degenerative Achilles tendinopathy is a conservative approach. The emphasis of treatment varies based on the stage of tendinopathy, however, the rehab progression is similar.
For a reactive Achilles tendinopathy, the treatment emphasis is on load management. Since majority of Achilles tendon pain is a result of overloading, this means reducing the amount of load placed on the tendon. Reducing some combination of the intensity, duration, or frequency of load on the tendon is the typical approach for managing the load. Examples of how to reduce intensity, duration, and frequency are provided below:
- Intensity: Decreasing either the speed of a run or limiting hill running
- Duration: Decreasing the time spent running each session
- Frequency: Decreasing the amount of days spent running per week
In a degenerative Achilles tendinopathy, the focus of treatment is to increase the capacity of the tendon to loading. Eccentric exercises, commonly referred to as negatives, is a common exercise used in the treatment of Achilles tendon pain. However, research suggests that there is no need to isolate the eccentric contraction and that concentric/eccentric contractions provide similar outcomes and may be better suited to how the muscles are used during sport. It might matter less what sort of contraction is performed for a degenerative tendinopathy and have more to do with the amount of load.
The rehab programs for reactive and degenerative tendinopathy programs follow a similar progression. The rehab programs generally start with isometric exercises to begin loading the tendon and to also help manage tendon pain (heavy isometric contractions have been shown to decrease pain for up to 45 minutes post exercise). Rehab then progresses to concentric and eccentric exercises. Concentric exercises are those when the muscle contracts as the muscle shortens while a eccentric exercise is a muscle contraction where the muscle lengthens.
The final stage of rehab is the most important for a safe return to running, and that is the plyometric exercise stage. Running, in it's most simple form, consists of small hops from one foot to the other. Plyometric exercises allow the tendon to become accustomed to this higher load on the tendon in a controlled environment.