Growing evidence has suggested high levels of intense exercise may actually damage your heart causing permanent structural changes resulting in an abnormal heart rhythm.
A review published in the Canadian Journal of Cardiology explores current controversies and makes the case for investing in large prospective research studies into the effect of intense exercise on heart structure and function.
Undoubtedly there are benefits of partaking in low and moderate intensity exercise, but convincing evidence supports the link between long-term sports practise and increased prevalence of atrial fibrillation and the fact that this relates to chronic altered atrial substrate.
This review by sports cardiologist André La Gerche, MD, PhD, provides a balanced discussion of data for and against the concept that intense exercise, particularly endurance exercise, may cause adverse cardiac changes in some athletes.
"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 fuelled an environment in which one may be criticised 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."
As Dr. La Gerche points out, all available therapies, pharmacological or otherwise, have a dose-response relationship whereby benefits diminish at high doses and the risk of adverse events increases. He suggests that this may even be possible for exercise.
"The answers regarding the healthfulness of ‘extreme’ exercise are not complete and there are valid questions being raised," continues Dr. La Gerche. "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."
So until we know more it may be wise to take it a little bit easier next time you head for a workout.