No, Endurance Exercise Won’t Kill You (Pt. II)
Enduro-philes, rejoice. More data has emerged to support your addiction, and to back a concept which I’ve explored once before on this blog (hence the “Pt. II”).
That concept being — endurance exercise, even at relatively high amounts (what some might call absurd) — won’t compromise your lifespan or healthspan. In fact, it will probably only add to it.
On the surface, this might seem obvious— exercise is good for us, right?. But, the idea that excessive exercise might be harmful is espoused by some high-level doctors and academics. Their fear comes from data indicating that high-level (endurance) exercise may actually damage the heart. More may not be better when it comes to exercise.
The argument is that a moderate approach to endurance training is a safer, more balanced approach to healthspan promotion. You don’t have to be an Ironman (or Ironwoman) to live until your 100th birthday. In fact, doing so just might reduce your chances of being a centenarian.
What type of “damage”might be caused by too much exercise? In an editorial for the British Medical Journal (BMJ) in 2012, cardiologists James O’Keefe and Carl Lavie cite physiological changes including overstretching and micro tears in the heart muscle, fibrosis (stiffening) of the heart wall, increased calcification, remodeling of the ventricles, and stiffening of the arteries. Interestingly, many of these are well-known changes that happen with “natural” aging.
And indeed, the authors of the editorial argue that excessive endurance exercise might potentiate “cardiac aging.” Some studies support this — showing that high-level endurance runners present more fibrosis and plaque than age-matched controls (non runners).
The data are compelling, and the anecdotes fear-inducing, yet the authors of this editorial make extreme endurance exercise out to be something no less dangerous than overdosing a lethal drug.
Lead study author (Dr. James O’keefe) talks about the perils of too much running in this TED talk.
Sure, one in a literal million endurance athletes will die of a cardiovascular event during activity and present with some form of heart abnormality upon autopsy (multiple athletes are cited in the editorial). In my opinion, this by no makes exercise the culprit. In fact, I’d argue that the myriad endurance athletes who don’t suffer the same fate are evidence against the “death by exercise” hypothesis.
While a “U-shaped” benefit for exercise most likely exists (meaning that above a certain threshold, benefits go away), the authors go so far as to conclude that “running too fast, too far, and for too many years may speed one’s progress towards the finish line of life.”
A bit dramatic? Perhaps. I believe we have much more to worry about on the opposite end of the spectrum — the extreme epidemic of sedentary activity and diseases of modernity. For most people, just moving enough is the issue.
For those who meet the criteria of “extreme” exercisers (including yours truly), there is some promising data from some recent reports on the link between physical activity and (a lack of ) cardiovascular death and disease.
The first, presented recently at the meeting of the American Heart Association (AHA), examined the effect of “extreme” exercise on cardiovascular mortality (death) and coronary artery calcium (CAC) — a marker of coronary artery disease. The question being — does “lifelong” high-volume endurance activity lead to a greater risk for cardiovascular death or disease?
The individuals analyzed were part of a larger study known as the Cooper Center Longitudinal Study — large database of patients enrolled at a wellness institute (The Cooper Institute) that is continuously updated and used to produce research data on individuals over a long period of time. This study has provided a wealth of information into the effects of aging and exercise on cardiovascular health throughout the lifespan.
Back to the study. This 10 year follow-up study examined a special group of individuals who were categorized as having high levels of physical activity — who were further divided into groups of “high” and “extraordinary” volume exercisers. On average, these people had been exercising for about 27 years (they were ~53 years old) — so it’s safe to say they were pretty dedicated athletes. The data confirmed this — average V02 max (maximal oxygen consumption) in each group was around 42 …which is stellar for someone over age 50.
Did obsessive exercise lead to ill health? Apparently not. Compared to the “high” exercisers, “extraordinary” exercisers — supposedly those putting their hearts at a greater risk — had no more coronary artery calcium OR cardiovascular deaths in the ~10 year follow-up period. In fact, the extraordinary exercise group had 0 deaths from cardiovascular disease (2 total deaths from other causes) during this time span; though this group did have a much smaller sample size to start with.
If extreme levels of exercise prime endorphin junkies for an early death due to heart disease, you might expect a higher body count in the “extraordinary” exercise group. They were doing just over 35 hours of exercise per week! Even the “high” exercise group reported logging over 11 hours of endurance exercise on a weekly basis.
Were they running to an early grave? Not according to these findings.
These results are supported by another recently published analysis of physical activity and risk of death. When death from all-causes ( “all-cause mortality”) and from cardiovascular disease were compared in people exercising the “recommended” amount vs. those getting well above the recommended levels— more was better.
Perhaps more interesting, in this analysis, there seemed to be “no upper limit” for the benefits of physical activity on reducing the risk of death. Going back to our “extraordinary” exercisers, this study tells us that all their pavement pounding is paying off in years of life gained.
The number of studies finding a positive association of physical activity with a longer and healthier life is near infinite. But that’s not really the “argument” here. We know exercise is good…this point needs no repeating.
Rather, ours is a discussion on whether or not you can do “too much” exercise. Does going above and beyond the general recommendations pose a harm to health? Is there a ceiling to the benefits one can gain from exercise?
Perhaps. You can do “too much” of anything — the dose makes the poison. Exercise is a stress, meaning that too much of it could be harmful. But those who warn against the perils of excess are basing basing their conclusions on some rare (yet provocative) data that extreme exercise promotes ill heart health, which I believe is a bit premature. A few exceptions don’t make the rule.
Though longitudinal studies like those above are compelling, they have flaws. Self-reported physical activity is hardly an objective measure of true amounts exercise, and we know that people are routinely bad at self-reporting lifestyle habits (especially diet).
We also have the issue of “healthy user bias” — in that those who exercise a lot also probably have other beneficial lifestyle habits — not smoking, eating healthy, more social connections, to name a few. These might all contribute to a longer, healthier life, due only in some part to physical activity.
My take? I’m going to continue my endurance exercise regimen in spite of any potential harms it may cause (which I believe are hyperbolized). I’m not doing it to promote longevity — for that I’d take a more moderate approach.
No, I’m doing it to feed my addiction, strengthen my body, and nourish my connection to myself and others. Something will eventually kill me, but it likely won’t be exercise.
References
DeFina L et al. Athletes Performing Extraordinary Physical Activity (>10,000 MET∙Min/Week) at No Greater Risk of All-Cause or Cardiovascular Disease Mortality. Presented at AHA 2019.
Blond K, Brinkløv CF, Ried-larsen M, Crippa A, Grøntved A. Association of high amounts of physical activity with mortality risk: a systematic review and meta-analysis. Br J Sports Med. 2019
O’keefe JH, Lavie CJ. Run for your life . at a comfortable speed and not too far. Heart. 2013;99(8):516–9.
