In Greek mytholog
y Achilles was held by his heel and dipped in the river Styx in an attempt to make him immortal - leaving only his heel exposed1. As runners we too have areas of weakness that can leave us exposed to injury.
Despite the fact that the Achilles tendon is one of the strongest tendons in the body it is one of the most common overuse injuries in runners, particularly those of us who are no longer in our 20’s and early 30’s. An Achilles tendon injury can be both debilitating and completely disheartening.
The Achilles tendon is comprised of the gastrocnemious, soleus and possibly part of the plantaris muscle. It is designed to endure tensile stress that occurs with muscle c
ontractions. Imagine a healthy tendon as a rubber band. It is able to withstand a certain amount of pulling and tugging- i.e. tensile stress. However at some point that rubber band is going to get small tears in it or completely breakdown. The older the rubber band is the more likely is it to slowly breakdown. The more times it is stretched to the limits the sooner it will snap.
Tendonopathy is chronic degeneration of the tissue that makes up a tendon.
Healthy tendons are made up of primarily type I collagen and some type III collagen. Collagen is the protein that strengthens a tendon. Now imagine that same rubber band after it snaps. You try tying it back together to do the same job but it is never quite the same. When a tendon is injured it repairs itself by replacing collagen I with collagen III which it not as strong, and it lays down in a disordered pattern. This repair process decreases the tendon’s ability to withstand normal tensile stresses making it even more vulnerable to injury later on.