Evidence Against Excessive Cardio?

bumblebums

Okay, I had a look at some of the studies alluded to in the WSJ article. I couldn't find the study on which the WSJ article gives the most detail (the one described in the last paragraph)--I am guessing it hasn't been published yet, and the people who authored it do not seem to have academic websites where they keep manuscripts. They do publish a ton, though, so this should be out soon.

None of the studies specifically talk about the effects of weekly running distances--unlike the study discussed earlier in the thread. So if you want to know how much running is too much on a weekly basis, the research discussed below does not directly speak to this. But it does find that marathoners have anatomical changes in their cardiovascular systems of a kind usually associated with cardiovascular disease. The evidence for that seems solid, but this does not necessarily translate into clinical risk.

Some links to actual studies, with my comments:

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http://www.mayoclinicproceedings.org/article/S0025-6196(12)00473-9/fulltext#abstract

Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise, Mayo Clinic Proceedings 2012, James H. O'Keefe, MD, Harshal R. Patil, MD, Carl J. Lavie, MD, Anthony Magalski, MD, Robert A. Vogel, MD, Peter A. McCullough, MD, MPH

This guy James O'Keefe does seem to have an axe to grind, as Mr. Hutchinson of Runner's World noted. As the cautious title suggests, the evidence for the adverse effects of hardcore endurance exercise (we're talking ultramarathons now) is not conclusive, although that article does cite some useful references on the minimum amount of exercise needed to see benefits (15 min a day) and the point at which additional benefits stop to accrue (60 min).


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http://www.nejm.org/doi/full/10.1056/NEJMoa1106468#t=articleBackground

Cardiac Arrest during Long-Distance Running Races, Jonathan H. Kim, M.D., Rajeev Malhotra, M.D., George Chiampas, D.O., Pierre d'Hemecourt, M.D., Chris Troyanos, A.T.C., John Cianca, M.D., Rex N. Smith, M.D., Thomas J. Wang, M.D., William O. Roberts, M.D., Paul D. Thompson, M.D., and Aaron L. Baggish, M.D. for the Race Associated Cardiac Arrest Event Registry (RACER) Study Group. N Engl J Med 2012; 366:130-140 January 12, 2012. DOI: 10.1056/NEJMoa1106468

First of all, I cannot believe an NEJM article was published with a pie chart in it. I thought it was a legit journal, and now I have my doubts.

Looked at heart attacks in marathoners and half-marathoners who just finished the race, by identifying them from internet coverage of races and then following through to get some clinical histories. Data on each person are correspondingly incomplete. The study uses mostly the length of race (full marathon, half-marathon, or shorter) and the sex of the runner as predictors because they didn't have access to other data for all the runners. The longer the race, the more likely the runner was to die from the cardiac arrest. Men were more likely to die than women.

There are many many methodological limitations here, which they honestly discuss towards the end.

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http://circ.ahajournals.org/content/127/7/791.short

A Meta-Analysis of Aortic Root Size in Elite Athletes, Circulation 2013, Aline Iskandar, MD; Paul D. Thompson, MD

Mixed linear model analysis of studies that looked at aorta enlargement found that aorta roots are larger in "elite athletes" than in "nonathelic controls". But there does not seem to be any clinical dangers associated with this enlargement, at least none that these studies have conclusively identified. This echoes the "potential adverse effects" thing in the O'Keefe study mentioned earlier.

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http://radiology.rsna.org/content/251/1/3.full

Is Marathon Running Hazardous to Your Cardiovascular Health? The Jury Is Still Out. Radiology 2009, Kibar Yared, MD, FRCPC and Malissa J. Wood, MD

This is a reply to an article in the same issue that reports on a study of the cardiovascular health of older marathon runners (>50 yo). As the title suggests, the authors are not convinced. As a reply, the article does not include any original research, but if you are inclined to be skeptical of the research on endurance athletes' cardiovascular health, this might add some weapons to your arsenal.

GiddyupTim

Pardon me, but these are not studies. The first is a review article. The others are surveys. They call them studies because that makes them sound more credible. But, they are surveys. They examined a bunch of runners, and, SURPRISE, they found running does not make one completely invulnerable to age or health related heart changes.
Such "studies" are by their very nature fatally flawed. If you looked at that many non-runners how many would have enlarged aortas? How many would have heart attacks.
If you did a similar survey of runners, and were looking at whether or not they get hit by cars, you would find some who did, and, if you were excitable, you might conclude that running was hazardous to your health.
The New England Journal survey is based on a group's reporting, which of course naturally would have become better over the years, perhaps compromising any conclusions one can make, and it found only 59 cases of heart-related deaths out of 10 million marathon participants.
I am not even going to bother to figure what the percentage of runners that is. I would suspect, however, that more people fell and hit their head, and died.
Should these findings be investigated? Sure. It is a thread. You gotta pull it. It might lead to something.
But, keep it in context, please. It does not deserve discussion at this point. There is an overwhelming amount of good data showing the anti-aging and anti-disease benefits of cardiovascular exercise.

BeachIron

Okay, I had a look at some of the studies alluded to in the WSJ article. I couldn't find the study on which the WSJ article gives the most detail (the one described in the last paragraph)--I am guessing it hasn't been published yet, and the people who authored it do not seem to have academic websites where they keep manuscripts. They do publish a ton, though, so this should be out soon.

None of the studies specifically talk about the effects of weekly running distances--unlike the study discussed earlier in the thread. So if you want to know how much running is too much on a weekly basis, the research discussed below does not directly speak to this. But it does find that marathoners have anatomical changes in their cardiovascular systems of a kind usually associated with cardiovascular disease. The evidence for that seems solid, but this does not necessarily translate into clinical risk.

Some links to actual studies, with my comments:

############################
http://www.mayoclinicproceedings.org/article/S0025-6196(12)00473-9/fulltext#abstract

Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise, Mayo Clinic Proceedings 2012, James H. O'Keefe, MD, Harshal R. Patil, MD, Carl J. Lavie, MD, Anthony Magalski, MD, Robert A. Vogel, MD, Peter A. McCullough, MD, MPH

This guy James O'Keefe does seem to have an axe to grind, as Mr. Hutchinson of Runner's World noted. As the cautious title suggests, the evidence for the adverse effects of hardcore endurance exercise (we're talking ultramarathons now) is not conclusive, although that article does cite some useful references on the minimum amount of exercise needed to see benefits (15 min a day) and the point at which additional benefits stop to accrue (60 min).


############################
http://www.nejm.org/doi/full/10.1056/NEJMoa1106468#t=articleBackground

Cardiac Arrest during Long-Distance Running Races, Jonathan H. Kim, M.D., Rajeev Malhotra, M.D., George Chiampas, D.O., Pierre d'Hemecourt, M.D., Chris Troyanos, A.T.C., John Cianca, M.D., Rex N. Smith, M.D., Thomas J. Wang, M.D., William O. Roberts, M.D., Paul D. Thompson, M.D., and Aaron L. Baggish, M.D. for the Race Associated Cardiac Arrest Event Registry (RACER) Study Group. N Engl J Med 2012; 366:130-140 January 12, 2012. DOI: 10.1056/NEJMoa1106468

First of all, I cannot believe an NEJM article was published with a pie chart in it. I thought it was a legit journal, and now I have my doubts.

Looked at heart attacks in marathoners and half-marathoners who just finished the race, by identifying them from internet coverage of races and then following through to get some clinical histories. Data on each person are correspondingly incomplete. The study uses mostly the length of race (full marathon, half-marathon, or shorter) and the sex of the runner as predictors because they didn't have access to other data for all the runners. The longer the race, the more likely the runner was to die from the cardiac arrest. Men were more likely to die than women.

There are many many methodological limitations here, which they honestly discuss towards the end.

############################
http://circ.ahajournals.org/content/127/7/791.short

A Meta-Analysis of Aortic Root Size in Elite Athletes, Circulation 2013, Aline Iskandar, MD; Paul D. Thompson, MD

Mixed linear model analysis of studies that looked at aorta enlargement found that aorta roots are larger in "elite athletes" than in "nonathelic controls". But there does not seem to be any clinical dangers associated with this enlargement, at least none that these studies have conclusively identified. This echoes the "potential adverse effects" thing in the O'Keefe study mentioned earlier.

############################
http://radiology.rsna.org/content/251/1/3.full

Is Marathon Running Hazardous to Your Cardiovascular Health? The Jury Is Still Out. Radiology 2009, Kibar Yared, MD, FRCPC and Malissa J. Wood, MD

This is a reply to an article in the same issue that reports on a study of the cardiovascular health of older marathon runners (>50 yo). As the title suggests, the authors are not convinced. As a reply, the article does not include any original research, but if you are inclined to be skeptical of the research on endurance athletes' cardiovascular health, this might add some weapons to your arsenal.

Thank you very much for posting these. I have some reading to do.

BeachIron

Pardon me, but these are not studies. The first is a review article. The others are surveys. They call them studies because that makes them sound more credible. But, they are surveys. They examined a bunch of runners, and, SURPRISE, they found running does not make one completely invulnerable to age or health related heart changes.
Such "studies" are by their very nature fatally flawed. If you looked at that many non-runners how many would have enlarged aortas? How many would have heart attacks.
If you did a similar survey of runners, and were looking at whether or not they get hit by cars, you would find some who did, and, if you were excitable, you might conclude that running was hazardous to your health.
The New England Journal survey is based on a group's reporting, which of course naturally would have become better over the years, perhaps compromising any conclusions one can make, and it found only 59 cases of heart-related deaths out of 10 million marathon participants.
I am not even going to bother to figure what the percentage of runners that is. I would suspect, however, that more people fell and hit their head, and died.
Should these findings be investigated? Sure. It is a thread. You gotta pull it. It might lead to something.
But, keep it in context, please. It does not deserve discussion at this point. There is an overwhelming amount of good data showing the anti-aging and anti-disease benefits of cardiovascular exercise.

I'm sorry, but once again, I have absolutely no clue how to respond to someone who refuses to read the words written in my OP and other posts in this thread, or who is bold enough to state that something "does not deserve discussion." If you are not intellectually curious about this subject that is fine, but I am.

bumblebums

Pardon me, but these are not studies. The first is a review article. The others are surveys. They call them studies because that makes them sound more credible. But, they are surveys. They examined a bunch of runners, and, SURPRISE, they found running does not make one completely invulnerable to age or health related heart changes.
Such "studies" are by their very nature fatally flawed. If you looked at that many non-runners how many would have enlarged aortas? How many would have heart attacks.
If you did a similar survey of runners, and were looking at whether or not they get hit by cars, you would find some who did, and, if you were excitable, you might conclude that running was hazardous to your health.
The New England Journal survey is based on a group's reporting, which of course naturally would have become better over the years, perhaps compromising any conclusions one can make, and it found only 59 cases of heart-related deaths out of 10 million marathon participants.
I am not even going to bother to figure what the percentage of runners that is. I would suspect, however, that more people fell and hit their head, and died.
Should these findings be investigated? Sure. It is a thread. You gotta pull it. It might lead to something.
But, keep it in context, please. It does not deserve discussion at this point. There is an overwhelming amount of good data showing the anti-aging and anti-disease benefits of cardiovascular exercise.

I am not sure what exactly your criteria are for a publication to be classified as a "study". I think you mean "experiment". But surely you understand that a controlled experiment studying heart attacks in marathon runners would be both expensive to conduct and ethically problematic. Can you explain what your ideal study would be, and how large a sample would satisfy you? The sample for the NEJM paper pooled data from 10.9 million long-distance running event participants, and it does cite incidence statistics on cardiac arrests. Here is a quote from the key finding:

"The overall incidence of cardiac arrest was 1 per 184,000 participants (0.54 per 100,000; 95% confidence interval [CI], 0.41 to 0.70). The incidence was significantly higher during marathons (1.01 per 100,000; 95% CI, 0.72 to 1.38) than during half-marathons (0.27; 95% CI, 0.17 to 0.43; P<0.001) and among men (0.90 per 100,000; 95% CI, 0.67 to 1.18) than among women (0.16; 95% CI, 0.07 to 0.31; P<0.001)."

donrdon

How many people run more than thirty miles a week? For those who do, how many have cardiac health as their main reason? I am betting zero. That kind of dedication involves more motivation than that. Even if they started for the cardiac benefits, anyone running 30+ miles a week is doing it because they enjoy it and is probably not going to be concerned with diminishing cardiac returns. Or they are doing it because they enlisted and cardiac health is the least of their concerns.

Agree with this.

bumblebums

How many people run more than thirty miles a week? For those who do, how many have cardiac health as their main reason? I am betting zero. That kind of dedication involves more motivation than that. Even if they started for the cardiac benefits, anyone running 30+ miles a week is doing it because they enjoy it and is probably not going to be concerned with diminishing cardiac returns. Or they are doing it because they enlisted and cardiac health is the least of their concerns.

Agree with this.

Look, when science agrees with common sense, there isn't usually much reason for debate. There is a clear relationship between physical activity (not just running, but running is pretty damn good) and well-being. Doing cardio is good for your heart and blood vessels. But the question in this thread is more subtle--is the relationship linear and additive (the more cardio you do, the better), or is it something other than linear? There is more than one alternative to linear. The benefits could flatline after a certain point: you stay at some level of fitness, but don't get anything extra other than bragging rights for being an endurance runner. Or it could be a U-curve, as some posters suggested, where after a certain point, you are harming yourself as much as you would by doing nothing.

I honestly do not think anyone in this thread (including myself) knows the answer. But it's a valid and interesting question.

BeachIron

I have been trying to find the "right" amount of running for several years. I've been in a running group that was trying to convince me I was eating too much protein and lifting too much, and then with the lifting groups telling me that I was eating too many carbs and that running is going to destroy my lifting progress. We all have to find our own approaches but I'm seriously trying to find the sweet spot for the maximum health and appearance benefits.

I do think anything can be taken to the extreme and finding balance is a good thing. I have seen a couple of articles similar to the one you posted. I think that some people jump much too quickly into things instead of working up slowly to achieve what they desire. And, every person is unique and so often we all forget that. What works for one may not work for another. Anyway, I think you HAVE found the "sweet spot" as far as your appearance benefits, You look great!!

Thank you. You're very kind! :blushing:

dixiewhiskey

How many people run more than thirty miles a week? For those who do, how many have cardiac health as their main reason? I am betting zero. That kind of dedication involves more motivation than that. Even if they started for the cardiac benefits, anyone running 30+ miles a week is doing it because they enjoy it and is probably not going to be concerned with diminishing cardiac returns. Or they are doing it because they enlisted and cardiac health is the least of their concerns.

Agree with this.

Look, when science agrees with common sense, there isn't usually much reason for debate. There is a clear relationship between physical activity (not just running, but running is pretty damn good) and well-being. Doing cardio is good for your heart and blood vessels. But the question in this thread is more subtle--is the relationship linear and additive (the more cardio you do, the better), or is it something other than linear? There is more than one alternative to linear. The benefits could flatline after a certain point: you stay at some level of fitness, but don't get anything extra other than bragging rights for being an endurance runner. Or it could be a U-curve, as some posters suggested, where after a certain point, you are harming yourself as much as you would by doing nothing.

I honestly do not think anyone in this thread (including myself) knows the answer. But it's a valid and interesting question.

I agree about no one knowing the answer. We are all unique so what works for one does not for all.

GiddyupTim

From previous post:
I am not sure what exactly your criteria are for a publication to be classified as a "study". I think you mean "experiment". But surely you understand that a controlled experiment studying heart attacks in marathon runners would be both expensive to conduct and ethically problematic. Can you explain what your ideal study would be, and how large a sample would satisfy you? The sample for the NEJM paper pooled data from 10.9 million long-distance running event participants, and it does cite incidence statistics on cardiac arrests. Here is a quote from the key finding:

"The overall incidence of cardiac arrest was 1 per 184,000 participants (0.54 per 100,000; 95% confidence interval [CI], 0.41 to 0.70). The incidence was significantly higher during marathons (1.01 per 100,000; 95% CI, 0.72 to 1.38) than during half-marathons (0.27; 95% CI, 0.17 to 0.43; P<0.001) and among men (0.90 per 100,000; 95% CI, 0.67 to 1.18) than among women (0.16; 95% CI, 0.07 to 0.31; P<0.001)."
[/quote]

Sorry to bog this thread down with argument, but

Even if data gathered in this manner was not extremely problematic, even if it was fair and valid to compare data from a survey like this with population data acquired in a wholly different manner, the difference of 0.90 to 1.01 appears to me to be so negligible as to be completely meaningless.
And, don't at least two of their confidence intervals cross 1? Doesn't that in itself mean that these findings could easily be found just by chance?

scottb81

And, don't at least two of their confidence intervals cross 1? Doesn't that in itself mean that these findings could easily be found just by chance?

No. It means there is a 95% probability that the true incidence of cardiac arrest for the whole population is between the two numbers, .41 to.70, and .72 to 1.38. To me these numbers seem to reflect common sense, i.e. that there is a greater probability of having a heart attack when running a marathon than when running a half marathon since one will be stressting the heart for over twice as long. The other way of looking at it is although there is a greater chance of encountering heart problems when running a marathon, the overall increased risk is pretty small and the overall risk is very small across the entire population.

Personally I would view these studies as good news. And as others have said, if you run marathons you are usually doing it for reasons other than heart health anyway.

bumblebums

And, don't at least two of their confidence intervals cross 1? Doesn't that in itself mean that these findings could easily be found just by chance?

No. It means there is a 95% probability that the true incidence of cardiac arrest for the whole population is between the two numbers, .41 to.70, and .72 to 1.38. To me these numbers seem to reflect common sense, i.e. that there is a greater probability of having a heart attack when running a marathon than when running a half marathon since one will be stressting the heart for over twice as long. The other way of looking at it is although there is a greater chance of encountering heart problems when running a marathon, the overall increased risk is pretty small and the overall risk is very small across the entire population.

Personally I would view these studies as good news. And as others have said, if you run marathons you are usually doing it for reasons other than heart health anyway.

What scottb said.

sozisraw

I have been trying to find the "right" amount of running for several years. I've been in a running group that was trying to convince me I was eating too much protein and lifting too much, and then with the lifting groups telling me that I was eating too many carbs and that running is going to destroy my lifting progress. We all have to find our own approaches but I'm seriously trying to find the sweet spot for the maximum health and appearance benefits.

good for you , am trying similar

wswilliams67

This is an old argument and is basically baloney. The ultimate takedown is here, written by an exercise physiologist for Runner's World

Yes I'm sure he is completely unbiased LOL. ;-)

faegrrrl

I think through my own PT that 20-30 minutes of cardio a day/5 days a week is all your heart needs. Anything over that and it puts stress n your heart. People don't realize that lifting weights does involve cardio, not to the extent of a full cardio workout, but lifting gets your heart pumpin'. :-)

VorJoshigan

I can't be bothered to give a crap about quantity of life. Give me quality any day. Unfortunately, I don't see many studies focused on that.

SpazQ

People might also want to read up on cardo and inflammation as well as cardio and cortisol.

My belief is that it isn't just about calories in vs calories out. I believe inflammation is a big key although finding studies is not easy. I am my own n=1.

As a celiac, I've had to learn about inflammation in regards to foods I eat (not just the ones with gluten). I've also had to learn how too much cardio with a too large deficit actually hinders me or makes me gain weight from bloat no matter what I eat. Inflammation.

We see it all the time. 1200 calories and an hour of cardio a day and no weight loss. If this is about calories in vs calories out, wouldn't it make sense that these people should be losing weight with such a plan?

Hexahedra

Another article:

http://well.blogs.nytimes.com/2011/03/09/when-exercise-is-too-much-of-a-good-thing/

sdpasque

This is an old argument and is basically baloney. The ultimate takedown is here, written by an exercise physiologist for Runner's World:

http://www.runnersworld.com/health/too-much-running-myth-rises-again

Money quote:

"But here, from the actual abstract, is the part they never mention:

"Cox regression was used to quantify the association between running and mortality after adjusting for baseline age, sex, examination year, body mass index, current smoking, heavy alcohol drinking, hypertension, hypercholesterolemia, parental CVD, and levels of other physical activities.

"What this means is that they used statistical methods to effectively “equalize” everyone’s weight, blood pressure, cholesterol, and so on. But this is absurd when you think about it. Why do we think running is good for health? In part because it plays a role in reducing weight, blood pressure, cholesterol, and so on (for more details on how this distorts the results, including evidence from other studies on how these statistical tricks hide real health benefits from much higher amounts of running, see my earlier blog entry). They’re effectively saying, 'If we ignore the known health benefits of greater amounts of aerobic exercise, then greater amounts of aerobic exercise don’t have any health benefits.'"

I think either you or the author of that Runner's World article are misunderstanding what a statistical regression does. A multivariate regression models the variance in the data with respect to the dependent variable (here, mortality rates). Let me break this down.

Suppose you want to know whether mortality rates are affected in any way by running. You happen to know from prior research that "baseline age, sex, examination year, body mass index, current smoking, heavy alcohol drinking, hypertension, hypercholesterolemia, parental CVD, and levels of other physical activities" (the other predictor variables mentioned in the abstract) contribute to mortality. There are two ways to answer your main research question: (1) match for all of these variables in the two populations you are studying, one of which runs and the other does not. This is going to be hard to impossible, given the number and nature of these variables. (2) Find out what the levels of these variables are in the population, and include them as predictors in your model. If, after including them as predictors, marathon running STILL accounts for some variation, then marathon running has an effect on mortality rates.

You might also be a bit confused about what it means when your predictor variables are correlated with each other. Runners may in fact be overall eat better, drink less, etc., etc. But they might not be. If you want to know the effect of running independent of the variables which are correlated with running, you have to regress running against these other variables and take the residuals and put them in your model as predictors.

What the study in question found was this (quote from the abstract):

"Running distances of 0.1-19.9 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."

What this means in plain English is that the study found no benefits to running more than 20 miles a week. It doesn't mean that there are no benefits, and it certainly does not mean that there are dangers.

Thank you for posting this. Most people don't understand statistical analysis and how one can separate out one variable without letting other confounding variables affect the results. I'm adding statistics to my list of courses that everyone in this country ought to have taken--along with four full years of economics in high school.

55in13

People might also want to read up on cardo and inflammation as well as cardio and cortisol.

My belief is that it isn't just about calories in vs calories out. I believe inflammation is a big key although finding studies is not easy. I am my own n=1.

As a celiac, I've had to learn about inflammation in regards to foods I eat (not just the ones with gluten). I've also had to learn how too much cardio with a too large deficit actually hinders me or makes me gain weight from bloat no matter what I eat. Inflammation.

We see it all the time. 1200 calories and an hour of cardio a day and no weight loss. If this is about calories in vs calories out, wouldn't it make sense that these people should be losing weight with such a plan?

A couple of things...

I deal with a different type of inflammation. That weight is fluid and it drains away when the inflammation subsides. Mine is joints and only swings the weight a couple of pounds. I don't think of it as gain since it is temporary, like having a big drink but not having peed yet.

The "I only eat 1200 calories and work out but don't lose weight people" - there are a few, maybe a couple of percent, that have some bizarre health issue that explains this. Most of the time there is an elephant in the room that we don't talk about here. A lot of posts are bogus; not necessarily purposeful deceptions but not accurate either. One or more of the numbers in the posts are wrong, because I am assuming the laws of thermodynamics are not failing. They are consuming more than they say, burning less or both. I think a lot of them really believe their numbers are accurate, but when they get those people in studies where the numbers are accurate the claims don't hold up.