By carbon testing tissues exposed to nuclear fallout in post WWII tests, scientists have found that despite repeated high-impact loading, the Achilles tendon is not renewed, but stays the same throughout adult life.
Achilles tendon injuries are notorious among athletes and trainers as career killers.
“Tendon injury is a very common disease, which hinders many people from enjoying the numerous benefits of sports and recreational activities,” said Katja Heinemeier, Ph.D., a researcher involved in the work from the Institute of Sport Medicine and Center for Healthy Aging at the University of Copenhagen in Denmark.
Heinemeier and colleagues made this discovery by taking advantage of carbon-14 spikes resulting from post WWII nuclear bomb tests.
Because of these tests, there was a large release of the radioactive carbon-14 (radiocarbon) to the atmosphere between 1955 and 1963.
This sudden rise in carbon-14 – called the “bomb pulse” – reached a maximum of twice the natural atmospheric level in 1963, and then gradually dropped to the lower levels over time.
This variation is reflected in all human tissue, because humans eat plants (and animals fed on plants) that take up carbon-14 from the atmosphere. Researchers studied the Achilles tendons from people who had lived during the carbon-14 bomb pulse peak, and found that the high carbon-14 levels of this period had remained in the tendon tissue for decades after.
This persistence of radiocarbon can only be explained by the fact that the rate of tissue renewal is extremely slow in the tendon, if it exists at all. In fact, the results showed that the Achilles tendon stays the same after growing ends.
In comparison, muscle tissue from the same persons had been constantly renewed and contained no “memory” of the radiocarbon.