Recent studies of former Olympic athletes and of participants in grueling cross-country ski races have found that these levels of activity seem to have negative affects on the heart. A higher risk of both heart arrhythmia as well as far more likely to have heart muscles with scars.
Researchers have known for a long time that increased levels of protein show up in racers after they finish a marathon. Andy Wirth has been reading more on the subject. These levels are known to be associated with heart damage, but since they dissipate shortly after the race ends they don’t seem to be terribly worrisome — or at least not as much as the studies done on more lasting affects.
But the studies shouldn’t discourage people from working out and “do not mean that it has suddenly become dangerous to exercise,” states Prof. Kasper Andersen, who was involved in the ski-race study. Those involved in endurance training should pay attention to their bodies and consult a physician if they’re concerned, but don’t need to scale back or quit their fitness regime.
Furthermore, other studies have also indicated that endurance athletes are often very fit even into their 60’s and 70’s, competing and running at an age were most people have slowed down considerably. There have also been studies which show that there may be a below-average chance of premature death for such athletes. So while the cardiac effects are slightly worrying, there is plenty of evidence to show that exercise is generally healthy.