Discussion: A threshold for dangerous exercise?

There was an interesting article in the NYTimes this week about endurance athletes. The gist of the article was that excessive exercise causes significant, dangerous changes in the heart:

...The results...were rather disquieting. None of the...older nonathletes had fibrosis in their hearts. But half of the older lifelong athletes showed some heart muscle scarring. The affected men were, in each case, those who’d trained the longest and hardest...

...There is no doubt that exercise in general is very good for heart health...[but] science does suggest that there may be a threshold of distance, intensity or duration beyond which exercise can have undesirable effects...Unfortunately, it remains impossible to predict just what that threshold is and which athletes might be most vulnerable to heart problems...

...The researchers also could manually induce disruptions of the heart’s natural electrical rhythm much more readily in the running rats than in the unexercised animals. Interestingly, when the animals stopped running, their hearts returned to normal...Most of the fibrosis and other apparent damage disappeared...

When they have SCD or other events, you (and the NY Times writer) get the right to call these changes dangerous, and the effects, undesirable. Without events, all we know is there's fibrosis. Perhaps fibrosis can lead to rhythm disturbances, perhaps not.

SCD = Sudden Cardiac Death, I assume.

Well I personally know athletes over 50 who have heart issues. True, they are still alive. But their heart issues have certainly changed their lifestyle...and their perception of their own health. Should they have backed off the annual marathon training 10-15 years ago, and given their heart a break once in a while?

As far as SCD, who's to say that fibrosis wasn't a factor in the death of running guru Jim Fixx, or some of the people who drop dead during marathons?

Up until now I think the athletic community has believed (wrongly) that the more exercise we get is beneficial...that there is no limit. That may be too simplistic an assumption; we may need to do a better job of monitoring and adjusting our workouts, particularly as we get older.

I don't know anybody in the serious (as in full-time more or less professional) athletic community that believes that training at the top level isn't damaging to your health in the long term. I really don't think that's the point. If it's what you do, you do it. Quality of life is more important than duration.

It would be interesting if every part of your body was susceptible to overuse injuries except your heart.

As far as SCD, who's to say that fibrosis wasn't a factor in the death of running guru Jim Fixx, or some of the people who drop dead during marathons?

Once I see papers to that extent, I'll believe it. Case studies that list naked fibrosis as cause of death, in the absence of serious artery blockage. Most case studies that I've seen indicated HCM or arterial blockage as causes of death, including the cases you mention.

This (NYT) article, and especially the conclusions Clark draws, are an example of how scientific findings are taken out of context by popular journalists and their readers unwilling or unable to consult the original sources, and how broad conclusions are drawn that are unsupported by the original evidence. In the case of most scientific articles, one needs not only to thoroughly understand the science in the article, but also read some or all of the underlying citations. How many readers of the NYT article have done that before drawing a conclusion?

It would be interesting if every part of your body was susceptible to overuse injuries except your heart.

It would be indeed. Presumably everything can be overused. Most runner's knees are prime examples. Running on hard surface kills knees, in many cases well ahead of killing other systems, and at relatively moderate levels not exceeding 300 hours/year. What constitutes overuse? Presumably running is not overuse of your CNS; taking methamphetamines is. The latter also abuses many other systems, as does running, and these other causes will kill well before the CNS abuse.

Is strenuous marathon training abuse of the heart? Many, including myself, seem to think that the heart—unlike the knees—was "designed" (evolutionarily selected) to withstand much higher abuse than the knees, and there is no reasonable threshold beyond which exercise becomes detrimental (save running with acute myocarditis)—if there is such a level, me and others are inclined to think you'll kill your other systems before you'll get to it. And, if you die of arterial rupture due to blockage, you would have died earlier due to more blockage had you exercised less. The Wilson article doesn't disprove these beliefs. The issue at stake is whether long-time, frequent racing (note that an article cited by Wilson finds that fibrosis was uncorrelated to the level and intensity of training) damages the heart. Once there is correlation and, better yet, causation established between fibrosis and SCD or other events, this question is answered.

I wouldn't worry about overtraining damaging the heart, there are other things you can do to counteract it anyway. Like, I recently read that egg yolks are a magic cure for aging.

If only the things the NYT prints were peer reviewed...

J-J, I saw that, too! I've been downing 1.5 dozen yolks a day ever since.

Oh, good! Now I can eat all those yolks that Hill leaves around 'cause she only eats the whites.

What have I done?!

That's what you get for looking like this:



and offering up health advice.

Oh for crying out loud...when will that photo die?!

My 143yo great great grand aunt swears by egg yolks.

Never

Certainly not if people keep bumping

A bit more fall-out from the NYTimes article in my OP above...here's an exercise physiologist's response on the dangers of marathon training in developing heart scarring and fibrosis. In addition the article has several useful links, and a lengthy Comments section. The article recommends shorter, higher intensity sessions rather than long endurance runs, and concludes:

....You exercise because it makes you feel better...it helps keep your weight at an optimal level...[treats] insomnia...insulin resistance...depression. If you’re a serious athlete, however, you may want to reconsider how you train....research has shown that replacing those long cardio sessions with shorter, high-intensity burst-type exercises...actually produces GREATER results in far less time...

Like OMG. Yes it recommends. Where in Mercola's post is there any link between the two peer-reviewed articles and his recommendations? How is his suggestion grounded in literature? Is there a link at all? "People die when they run. Therefore you shouldn't run." Or, in Mercola's case, "therefore you should follow my program". On what grounds? Where are the numbers? What's the metric; is it performance, cardiac health, longevity, or hard-to-quantify overall happiness? Are there articles that compare rats who underwent the kind of training the Circulation article describes, and rats who underwent the analog of his short-burst program, then were dissected and their hearts looked at? When Mercola does this, or sponsors some academic department to do this, then and only then does he gain the license to put forward his suggestions. The same goes to the majority of bloggers and writers who seized upon the poorly-written, alarmist NYT article, to propagate theories of their own. Cut your own damn rats, then show them to us, then talk about it.

I really wish they'd have Cargo Cult Science as mandatory reading in med schools. (They have in most "hard" science departments.)

Well requiring double-blind, peer-reviewed studies of every proposed training program might take a little time, and a lot of money. Meanwhile, we have the results of this recent study that raises a red flag about traditional training techniques...should we just ignore it? Or can we incorporate some of it into our daily training?

I don't know if this Mercola has the answer; what he advocates is hardly new. The "short busts" or fartlek strategy seems reasonable to me. And on the advice of another a/p'er I've already incorporated something along those lines into my morning rowing sessions. I like it.

The statements I have problems with (see Cargo Cult) are (1) raises a red flag about traditional training techniques, and (2) the subsequent conclusion that other training techniques must surely be "better" in some way. After some thinking, I'm sure even you, Clark, will agree that there is absolutely nothing in Mercola's article you are citing that supports (2). Maybe if you do mostly intervals at age 50 instead of something more along Lydiard's lines, you'll fall over dead faster. Maybe not. We don't know. There's no data. If you know, please point us towards peer-reviewed lit.

The major issue is (1). The NYT article is the one that raises the red flag about "traditional training techniques". Wilson's article does not. It only states that a large portion of a small sample of people subject to a very wide variety of training and racing programs, the only common thing among which was the number of marathons completed, developed fibrosis. The fibrosis in itself is not necessarily a red flag; we won't know until there's SCD in these same people with fibrosis, or other serious events, or a large number of them die prematurely of some other cause. Another article (Möhlenkamp) cited by Wilson states that a similar effect was unrelated to the amount of training; only to the amount of racing. The findings of Möhlenkamp may be relevant to the sample examined by Wilson and colleagues, or they may be not, as the sample in Möhlenkamp's article was found to have a high likelihood of CVD predating the onset of the exercise program, which Wilson's sample's athletes did not. Maybe the fibrosis in itself is benign, and the events that Möhlenkamp's athletes did end up in (nobody died, BTW) were due to other factors. Maybe the fibrosis is life-threatening; to show that, perhaps, it wouldn't be necessary or humane to wait for Wilson's old foks to keel over, just follow up on the Circulation's rats and see what their lifespan is.

All of what I am proposing will be good science, helpful to all of us who are training and hoping this training would not only benefit our performance but also the lifestyle as a whole. Pseudoanalysis like NYT's, or, much worse, the many bloggers' who took the liberty of speculating and cargo-culting the crap out of Wilson's findings, is not helpful.

Here's a 2010 review article discussing and comparing both high-volume and high-intensity training. From the summary:
".... It would appear that a polarized approach to training may be optimal, where periods of both high and low-intensity training but high volume training are performed. ..... A further understanding of how best to organize and manipulate the training programs for future intense exercise athletes will require the continued cooperation of sport scientists, coaches and athletes alike."

The low volume, high intensity training philosophy had it's chance; 70 years ago. It quickly fell out of favor when athletes employing high volume, high intensity started kicking the asses of those reluctant to switch. That simple fact is too often overlooked by the authors of these studies. What is also often overlooked is the fact that most serious athletes don't give a rats ass if they are incurring long-term health problems in pursuit of their goals.

Why is quality vs quanity always posed as a choice? It should be neither or both. If you aren't doing high-intensity sessions, there's no benefit to a big base. If you are, you need the base or you'll get injured. Show me the low-volume runner who runs a 2:10 marathon and I'll eat my words. Until then, bring on the miles.

One point that's missing in this discussion is if you train when you're sick. Some viruses, especially those that cause the flue and sore throats (so anything with fever and sore throats) can invade the heart muscle tissue and cause inflammation (myocarditis) and scarring. if you exercise while sick, especially if you train with a high intensity, virus invasion into the heart muscle is promoted. Sure, you would not find that in people that are not exercising...

Alot of endurance athletes are overtraining themselves or are doing it at very intense levels that their body couldn't sustain over a period of time.

Here's a training formula developed by Phil Maffetone in the late 70's based on HR. http://philmaffetone.com/180formula.cfm. This more popular among triathletes. But this one is the only article I've found with scientific basis (long years of research).