There is growing evidence that high levels of intense exercise may be cardiotoxic and promote permanent structural changes in the heart, which can, in some individuals, predispose them to experience arrhythmias.
Just as most therapies have a dose-response relationship whereby benefits diminish at high doses and the risk of adverse events increases, high level of intense exercise may also be bad for the heart, suggests a new study.
The researchers reviewed studies that looked into the relationship between exercise and heart problems and found that there is growing evidence that high levels of intense exercise may be cardiotoxic and promote permanent structural changes in the heart.
"Much of the discussion regarding the relative risks and benefits of long-term endurance sports training is hijacked by definitive media-grabbing statements, which has fueled an environment in which one may be criticized for even questioning the benefits of exercise," explains Dr. La Gerche, who is Head of Sports Cardiology at the Baker IDI Heart and Diabetes Institute, Melbourne, Australia. "This paper discusses the often questionable, incomplete, and controversial science behind the emerging concern that high levels of intense exercise may be associated with some adverse health effects."
'If you're an athlete, you're probably more likely than a non-exerciser to trigger a dangerous heart rhythm because the heart is working more intensely - but only where an abnormality is there to start with.'
So if you do intense exercise with one of these conditions it can increase the risk of a life-threatening heart rhythm, he says.
That's why anyone starting an intense regimen involving exercising so hard that you can't talk in normal sentences should check with their GP first, in case they recognize symptoms.
These include dizziness, sudden loss of consciousness, palpitations or chest pain during or after exercise.
Light exercise with these conditions is OK, but heavy weightlifting, competitive sports such as football or basketball, with stop-start moves, or extreme endurance events, such as marathons and triathlons, are not recommended.
"Given that this is a concern that affects such a large proportion of society, it is something that deserves investment. The lack of large prospective studies of persons engaged in high-volume and high-intensity exercise represents the biggest deficiency in the literature to date, and, although such work presents a logistical and financial challenge, many questions will remain controversies until such data emege," La Gerche observed.