Heart damage from too much training??

Introduction

There’s been some recent media speculation that older endurance athletes are more prone to heart problems than healthy age-matched people. Just after one of our readers advised me of this negative press, a mate in his mid-60’s and pioneer of Ironman triathlon in Australia and now a lecturer in sport coaching at an Ozzie university told me he has had a pacemaker inserted. This goes against the common belief that aerobic exercise is good for you in that it keeps many of the heart disease risk factors in check. So what does the research really say when it comes to this supposed increased risk of heart problems in older endurance athletes?

The Facts

Exercise is increasingly been seen as medicine. In fact, internationally, there has been a movement started called Exercise is Medicine. The movement is being driven by the enormous amount of scientific evidence supporting the value of doctors prescribing exercise as medicine rather than pills!! Consistently and unequivocally recent research has found that regular exercise prevents and treats many of our common and deadly chronic diseases including:

  • coronary artery disease
  • diabetes
  • obesity
  • high blood pressure
  • heart failure
  • depression

Moreover, people who do regular physical activity have lowere rates of disability and an average life expectancy about 7 years longer than non-exercisers.

However, as with any drug there appears to be a safe upper range dose of activity above which there may be adverse effects that may outweigh the benefits above. For example, a long-term study published in 2011 in the highly prestigous medical journal the Lancet tracked 416,000 Taiwanese people over about 8 years and found that there was a protective health effect up to about 60 minutes of daily vigorous (huff and puff!) exercise. Another recent longitudinal study 0f 52,000 adults found that running distances of up to 19.9 miles/week, speeds of 6-7 miles/hour, or frequencies of 2-5 days/week were associated with a lower risk of all-cause mortality, whereas higher mileage, faster paces, and more frequent running were not associated with better survival.

Very recently, there has been some suggestion that long-term endurance vigorous training such as that greater then the doses above may increases the risk of atrial fibrillation (irregular heart beat). This review article presented many studies conducted over the last 15 years that have suggested training too hard for too long can increase the risk of atrial fibrillation in healthy middle-age men. They suggested that although such training may prevent coronary artery disease, it might also cause of atrial fibrillation.

An increasing amount of research evidence also suggests that training and competing long term in ‘extreme’ endurance events such as marathons, ultramarathons, ironman triathlons and very long cycling or swimming events can cause transient problems and damage to the heart walls and chambers as evidenced through blood markers. However, these problems return to normal within 7-10 days after stopping training.

In veteran extreme endurance athletes such as my mate, this consistent heart muscle damage and repair process may lead to heart fibrosis (thickening and stiffening of the heart valves and muscle). Over years, this may lead to heart arrythmias (irregular heart beats).

However, recently another group of cardiology researchers critically analysed these studies that suggested increased risk of heart issues in older endurance athletes (like me and my mates) who train long and hard and often. These researchers concluded that the

  1. the incidence of atrial fibrillation in middle-aged endurance athletes is rare
  2. if a risk exists, it is limited to vigorous endurance exercise only and in those middle-aged men with other risk factors such as smoking or high blood pressure
  3. there is no increased risk in healthy middle-aged men with a normal heart who have no blood pressure issues and no other risk factors
  4. Critically, the researchers concluded that the beneficial effects of exercise will offset this low risk which, even if increased, remains very low.

The So What?

As with any issue in science, research typically is inconclusive. There are always studies and papers that contradict each other. While a number of studies over the years have shown a potential increased risk of heart issues in older athletes who train long and hard and often, other studies suggest the risk is very low in these athletes if they are healthy and have no other risk factors. Moreover, the current concensus appears to be that while the the risk is very low, the benefits of such training outweigh the low risk of heart issues. For me, I intend to keep training regularly unless my body tells me otherwise!

Chapter 4 (Principles of Training the Masters Athlete), Chapter 6 (Endurance Development in the Masters Athlete), Chapter 10 (Periodisation and Peaking for the Masters Athlete), Chapter 13 (Preventing Overtraining in the Masters Athlete) and Chapter 14 (Staying Healthy and Illness-Free) are excellent guides and how-to chapters when it comes to optimising your training and preventing health issues as an older athlete. Each chapter is now available online as a pdf. Check it out by clicking here.

Sources:

  1. Delise, P. and others (2012) Does long-lasting sports practice increase the risk of atrial fibrillation in healthy middle-aged men? Weak suggestions, no objective evidence. Journal of Cardiovascular Medicine, 13: 381-385.
  2. Patil, H and others (2012) Cardiovascular damage resulting from chronic excessive endurance exercise. Missouri Medicine, 109(4): 312-321.