Extreme strenuous workouts such as high intensity training could be bad for the heart, a new study has warned.
Australian researchers say intense endurance exercise may be ‘cardiotoxic’ and cause permanent structural changes in the heart.
This, in turn, can leave some people more at risk of heart rhythm problems – known medically as arrhythmias.
The scientists say while there is no doubt a couch potato lifestyle is bad, when it comes to exercise, there really may be too much of a good thing.
But they argue much more research is needed before a definitive link can be made..
Previous research has linked long-term sport and exercise with an increased risk of atrial fibrillation – an irregular and often abnormally fast heart rate.
But the issue is controversial, with other research not showing a link.
In the new study, sports cardiologists at Baker IDI Heart and Diabetes Institute, Melbourne, reviewed data on the subject in an attempt to ascertain if high-intensity exercise does negatively affect the heart.
Head of Sports Cardiology, Dr André La Gerche, said: ‘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.’
He added that all therapies, pharmacological or otherwise [such as exercise], have a dose-response relationship whereby benefits diminish at high doses and the risk of adverse events increases.
An open mind would consider that this may even be possible for exercise, he said.
The study, published in the Canadian Journal of Cardiology, explored whether intense exercise – particularly endurance exercise such as marathons – may cause adverse cardiac changes in some athletes.
The study explored whether intense exercise – particularly endurance exercise such as marathons – may cause cardiac changes for some
It had been thought that athletes who suffered heart problems were already susceptible to them – due to an underlying abnormality – and exercise acted as a trigger.
This study looked at whether exercise alone can change the heart and trigger a heart rhythm condition in its own right (and excluded inherited conditions).
Controversies explored included:
* Do elite athletes live longer because of exercise or because they avoid smoking and alcohol?
* Is endurance exercise in athletes associated with arrhythmias?
* What are the potential mechanisms that predispose athletes to arrhythmia?
* Is the risk of ischemic heart disease increased with intense exercise?
He noted many of these controversies are based on small studies that are dwarfed by the large population studies supporting the benefits of exercise, albeit in doses of exercise less than those commonly practiced by elite sports persons.
He said: ‘The answers regarding the healthfulness of ‘extreme’ exercise are not complete and there are valid questions being raised.
‘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 emerge.