Elite runners don´t experience the same muscle weakening associated with ageing as non-athletes do, and now a new study has sought to find out why.
Muscle weakening occurs when the muscle fibres contract more slowly and with less force. So a team of Canadian researchers hypothesized that the constant physical training of older elite runners preserved their muscle fibres, making them behave like those of young adults.
The scientists took muscle fibre samples from the quadriceps of older elite runners and non-athlete adults in the same age range, as well as 23-year-old non-athletes.
The athlete participants were “exceptional”, according to lead author Geoff Power of the University of Guelph in Canada.
“These are individuals in their 80s and 90s who actively compete in the world masters track and field championships. In the study we had seven world champions, and everyone placed in the top four of their respective events.”
Tests measured the contraction speed and force of the muscle fibres.
Results published in American Journal of Physiology — Cell Physiology show that the muscle fibres from the older non-athletes contracted considerably slower and weaker than fibres from the young non-athletes. But the researchers were surprised to find that the muscle fibres of the athletes contracted at a speed and force similar to those of the older non-athlete adults, not the young adults.
This means that ageing is associated with decreased muscle quality regardless of physical activity status, and suggests that success in high-performance sports in old age is not due to maintained contraction capability of the muscle fibres, Power said.
So what´s going on?
Other studies have shown that muscle fibres can be arranged in a variety of ways to optimize strength, speed and power of the whole muscle, said the American Physiological Society, reporting on the latest study. As a result, there are many structural ways to compensate for the reduced performance at the fibre level to maintain performance at the whole muscle level, Power explained.