For many runners, the achilles tendon is often associated with the pain and frustration of the achilles tendonitis injury. The low blood supply to the tendon can lead to long recovery times. However, many runners don’t know that, while the tendon might be painful from time to time, it is perhaps the single most important part of the human body for running.
The most amazing thing about the achilles tendon is its strength. The tendon is built to withstand over seven times a person’s body weight when running.
The ability of the achilles to absorb this tremendous weight on every step allows runners to push off on their toes and propel themselves forward. The achilles tendon greatly increases the ability of humans to run at top speeds.
In his excellent book, Born to Run, Chris McDougall explains the importance of the achilles tendon not only in everyday running, but in the evolution of the human race. The fossil evidence shows that achilles tendons first began to appear in human ancestors relatively late in the evolutionary time period.
The appearance of the achilles tendon may have given our ancestors an advantage over other hominids, such as neanderthals. The fossil record suggests that neandertals had a shorter achilles tendon, which may have given their competitors, the predesessors to modern-day humans, a distinct advantage in the fight for the survival of species.
The strength of the achilles tendon lies in its elasticity. Unlike the rigidity of bones and most muscles, tendons are analogous to rubber bands in way that they store and return energy. As the tendon stretches, it stores energy that is returned when leg swings back during a running stride. The spring-like, recoil effect of the achilles tendon after it is stretched allows humans to run far while saving energy. The tendon makes humans one of the most energy-efficient running creatures on the planet.
The bottom line to all of this is that the achilles tendon is a remarkable product of evolution that allows humans to run fast and efficiently. If evolution never provided us with the achilles tendon, it is likely that we would be similar to the chimp, which has no achilles tendon and, as a result, is not able to run far distances. So the next time you are cursing your achilles for the pain you are experiencing during the latest injury, keep in mind that without that tendon, humans would not be able to run to far at all.
Photo courtesy of Paul Foot
