Monday, August 1, 2016

Cardio May Be Killing You - Part 2

Part 1 was way back, one month short of five years ago.  First, a short refresh.  The main thrust of the article concerned data from a radiology study, that was written for popular press by Kurt Harris, M.D..  In brief, when distance runners who did three marathons a year were compared to sedentary people, which even included some smokers, the runners showed more evidence of so-called "silent" heart attacks and had more damage to their hearts than the other groups.  The runners were slimmer and (of course) fitter, but their hearts were in worse shape than sedentary people.  From a heart health standpoint, they were less healthy than the ones who sat around - and how often have you heard or been told by a doctor not to be sedentary? 
Dr. Harris said that the evidence was strong enough to convince him to change his behavior.  He switched to running a 5k (~3 miles) a few times a week just for fun, and abandoned the "more is better" belief about cardio that is absolutely pervasive in our society.

Given that as background, and as I said at the time my tendency to listen to "alternative" nutrition/health podcasts, I ran into some data on one of them that I've researched somewhat, and I think it's real enough to add a Part 2 to the previous post.  The interviewee I was listening to was Mark Sisson, one of the founders of the paleo diet and exercise movement.   Sisson was a world-class marathoner and triathlete before he quit.  He long decried what he called "chronic cardio" - getting on a bike or running until heart rate is 80% of maximum and sticking it there for hours. 

One of the most common heart arrhythmias is atrial fibrillation, or afib.  Afib can be very uncomfortable, but most importantly it raises the risk of stroke.  One source I saw said it's the leading cause of stroke in America.  It turns out that doing extensive cardio exercise not only can cause the silent heart attacks mentioned in '11, it can damage the heart in ways that cause afib.  In this 2013 article, on a peer-reviewed medical practitioner's page, they say that afib is 5 times more common in endurance athletes than the general population.  That may be a low estimate.  The risk is greatest for people who start their vigorous exercise programs (defined as >5 hours/week) when they're over 30.  Sisson said he has afib, many of his contemporaries have it and went so far as to say it's endemic in over-50 ex-athletes.  I spent most of my exercise time for a decade or more doing exactly that, from the mid-90s to the mid 2000s.  Typically 5 or 6 days a week, I'd nail my heart rate high and just crank out the miles.  A few years ago, after some weird chest sensations, I was told I have afib, and an older friend who was a runner for his entire adult life has it.  (I've never had symptoms as bad as my friend).

In this article from a cardiac electrophysiologist and bike racer, he talks about the bitter truth about this situation.  Once the heart is damaged, it's damaged irreversibly.  There are two main treatments for afib: anti-arrhythmia drugs and a surgical intervention that either "spot welds" areas of the heart together, to break up the problems causing the afib, or cryoablation that freezes and "burns off" that heart tissue.  Either one of these is a Big Deal, and while they don't crack your chest open as in the case of bypass surgery, they feed a catheter carrying instruments and a camera up the femoral artery into the heart.  It's done under general anesthesia.  The drugs bring bad side effects to some people, but work for others.  The ablation treatments sometimes fail and need to be redone.  My friend had cryoablation twice, and it seems to be holding up.

Don't make the mistake of suddenly stopping your exercise program.  In a study at the Karolinska University Hospital, in Stockholm, Sweden, they collected information about physical activity from 44,410 Swedish men from the ages of 45-79 who did not have atrial fibrillation.  They found a U-shaped curve of exercise vs. risk of afib.  The lowest risk was at 2-3 hours per week. The risk was highest in those that started >5 hours of vigorous exercise after the age of 30.
In men who exercised >5 hours per week at age 30 and quit exercising later in life or regressed to <1 hour per week, the atrial fibrillation risk increased further to 49 percent. The increased risks remained even when accounting for all types of heart disease and heart disease risk factors; diabetes, high blood pressure, and being a smoker.

These authors made a second important observation. They found that leisure activity of walking or cycling did not increase risk, even if it was over 60 minutes a day. In fact, walking over 1 hour per day was associated with a 13 percent decrease in atrial fibrillation. This lower risk of atrial fibrillation was seen in almost all of the groups and was independent of what age the activity was started. In fact, becoming more active with low-moderate intensity exercise helped lower all traditional risk factors of heart disease as well as atrial fibrillation.
The thing about this that bothers me the most is that this research goes back at least as far as 1993, and I don't see any messaging anywhere saying there are negative risks associated with doing this sort of cardio workout, and to be especially careful if you're over 30 and start running (or riding).  Likewise I've never seen the advisories about running marathons I talked about five years ago.  Personally, when someone tells me "irreversible heart damage", I don't like those words.  I suppose some group or other thinks it sends mixed messages when they believe they can't get the majority of people to exercise at all.

I don't like closing an article like this with no signs of hope, so let me reiterate that leisurely walking or cycling was associated with a reduction in afib.  It appears that a leisurely walk around the block/neighborhood, a few times a week, or every day, is the best thing you can do - at least as far as afib is concerned!
(with all due respect to the folks I got this image from, the most important thing to know before attending a spinning class is DON'T!!!)


  1. Things we have known for thirty years.

    1. This is a perfect example of why people who want to run will ignore things like this. They'll seize on the fact that his father died at 35 and say, "sure, Jim died too early, but he lived almost 20 years longer than his dad, so running helped him live longer". I remember hearing this (I was 3 or 4 times a week runner in '84). As far as I know, there's just no way to know if that's true.

      In that article by Dr. Harris I linked to, he talked about Alberto Salazar, the Olympic marathoner who almost suffered the same fate as Jim Fixx. He had a heart attack after a run, but people were available to resuscitate him.

  2. Much many interesting.

    I think a lot of us have slid butt-first down the rocky slope of "cardio is good" from all the way back to junior high; why would the coaches have us run so much if it weren't good?

    I realize research is just beginning, and there's a lot of exercise myth to be overcome, but it would be interesting to see data - whenever someone has done the solid research that leads to good data - on what the optimum heart rate is for the optimum length of time under the optimum load to develop, and maintain, optimum health.

    I suspect that's data our grandchildren may be able to see; it's too late for us, and probably our kids as well.

    Sounds like the Boston Marathon and the Tour de France are development tools for creating future invalids. Then again, so is a Barcalounger.

  3. We will never know the truth. Too many ties between universities, business and government and the big bucks involved to kill this goose egg. They gots to keep selling us all the stuff, supplements included, to help everyone "feel" fit. Common sense isn't enough. Moderation in everything. Participants have made this their religion so there is little arguing with them especially when the effects are so far down the road. "Oh, that won't happen to me." That will be their defense. I'm in great shape!

  4. A general note I should have put in the original article. One of the problems with trying to get this message into the population is the mental image these athletes have of themselves. Not just that they're really tough, but that they're a different type of person than "mundanes" (to borrow a term). I remember a saying I read in the late 70s that went, "A jogger jogs because he thinks it will make him healthy. A runner runs even if he thinks it will kill him."

    The other problem, of course, is that people perceive of the problem as being "way out" when they're older. Afib is being seen in endurance athletes in their 30s.

  5. It is illogical. A engineer would reject the premise. Are their studies that show everything and I mean conflicting and contradicting things? Yes! There are studies that show not doing cardio excercises is harmful and vice versa. If you want to prove a point you do not have to bbe correct simply a statistician. It is illogical and contrary to what we all see and know everyday that running causes heart disease.

    What does cause heart disease? MOSTLY genetics. If your dad died at 50 from heart disease than you need to worry. If you family lives into the 80's it is unlikely with or without cardio that you will die in your 50's of heart disease.

    As for the fad diets. IMHO as soon as someone begins claiming that the latest fad diet will make you live forever it's time to tune out. Food is food unless you have some disease that requires a specific diet.

    1. I actually don't disagree with your second or third paragraphs at all. Where we disagree is that saying an effect documented, in many studies and verified in animal models is stupid. The numbers I came across ranged from a relative risk increase (for afib) of 5 to 10 times. Feel free to argue that it's not a big risk even at 10x normal, the point is: does anybody tell patients there are trade-offs? Does anybody say, "more is not necessarily better"? Does anybody say, "I know you love your bike racing, but are you aware of the risks?" Dr. John M (one of my links) does, but he's also a specialist; by the time he sees people, they already have the damage.

      Saying, "there are studies that show contradicting things so let's ignore all studies" sounds like a cop out. If you reread the piece, you will note I didn't say running causes heart disease. I cited studies that showed runners had more evidence of asymptomatic heart attacks and endurance athletes had a higher risk of afib. Those are not the normal definition of heart disease.

      Look, the only thing we can be sure of in life as that we all die, right? We don't all get to make it past 90 or 100 and pass peacefully in our sleep. All you can possibly do in any exercise or lifestyle effort is push your odds toward one outcome or another. Would you rather die of a sudden heart attack or have a stroke, lose control of half your body, and spend your last days trying to relearn things you learned at age 3? Cancer? I've lost way too many friends to cancer, and getting disassembled piece by piece while nauseated all the time doesn't sound real good either. Comparatively, I've always thought the heart attack sounded pretty good.

    2. The problem is that many/most studies were intended to prove the authors bias. I remember a study on damage to our eye sight from computer screens. They had three groups by age. Something like 18-29, 30-45 and 46-60. In two of these groups there was a decrease in vision which they eagerly attributed to computer screens. However they left out the third result which was that essentially the group 30-45 had their vision improve. Of course they left it out because it failed to support their bias/belief. BUT, the worst part is that the statistical amount of the decreased vision was small, too small to be statistically significant. And the real irony was that for the third group with that statistic going the other way that small difference was exactly equal to the sum of the other two statistical results. In other words if they had looked at all the age groups together there would have been zero change in vision attributable to computer screens.
      Is this rare or random? Not at all. Studies are typically undertaken to prove a specific point. NOT to disprove it if the study disproves it then it is buried. The data, the test, the sample, what is left in and what is left out is carefully selected to gett the results they want

      Let me give you a completely different example. Heart attacks happen at different times but MOST heart attacks happen between late Sunday night and early Monday morning and typically while the patient/victim is sleeping. Who knows why. Maybe church is bad for you or sleeping or thinking about going to work next day. But what does it mean? Who knows but you can bet your life if it could possibly mean that eating meat was bad or exercise was bad or drinking all night was bad it would be touted as such. But it is probably meaningless and thus not worthy of a headline.

      Why did someone decide to study if vigorous cardio was possibly causing heart attacks? The answer is simple; they are no fan of cardio and feel the need to make it the bad guy.

      If something looks like a duck, quacks like a duck and walks like a duck it is probably a duck. If cardio caused serious heart problems by a factor of 5 to 10 times most runners would be dead instead of posting their view here. But in fact the single most significant factor in heart disease/attacks is genetics. Simple as that. We all die of something and dying from a heart attack in your 80's is the very definition of dying of old age. It is normal, what we can all expect if cancer and stroke don't get us first. It's the heart disease and deaths at age 45 or 50 or 60 that are a concern. And almost ALL of them are genetic. NOT from lots of cardio or red meat or being overweight. But if you read the studies you would never know that.


    8. In nature, the optimum is almost always in the middle somewhere. Distrust assertions that the optimum is at an extreme point.

  7. Anon 0805 @1709 All well and good, but you persist on seeing something that is not written in piece In particular, to use your quote, If cardio caused serious heart problems by a factor of 5 to 10 times most runners would be dead instead of posting their view here. Show me where it says that, word for word, like I just copied and pasted your words.

    What I said was that aerobic exercise increased the risk of afib - atrial fibrillation - that amount. Again, I'll paste my own words here: The numbers I came across ranged from a relative risk increase (for afib) of 5 to 10 times.

    I don't know how much clearer I can be. This piece is about atrial fibrillation, not heart attacks.

    1. Is atrial fibrillation a major risk or indicator of heart attacks? If the answer is yes and if cardio gives you 10 times the numbers of AF then yes there would be dead runners all over the place.

      What was written in the piece were a few dog whistles:
      "appear to be much healthier than those on the SAD - the standard american diet." This is the typical thing said by someone who has an axe to grind about diet or American diet or eating meat or fat or refined carbs. Than they make the leap using stats to prove how right they are.

      "I'll do my best to convince you of just how disturbing this study should be to those who believe that "aerobic" exercise will make you immortal." Does this sound like someone who likes cardio or someone with an axe to grind?

      "I am obliged to point out that by the conventional arbitrary criterion used in biomedical publishing, the difference was "not statistically significant". This should be self-explanatory and a red flag.

      "in the Breuckmann study, they recruited 102 active marathon runners... There were 102 totally asymptomatic age-matched controls" 102 is not a valid study. 30,000 would be a good number to hang their hats on.

      It is not my intent to simply argue with you on this issue. I apologize for "arguing" and simply add that to me it is simply a discussion. In my humble opinion these kinds of so-called studies and news releases happen all too often and are typically nothing more than the author trying to 'fix' the stats or prejudice the court of opinion. I am by nature skeptical and I have over the years discovered that so often what passes for science is in fact junk science.

      I thank you for your patience.

    2. As far as I know, afib is not associated with increased heart attack risk. It's associated with increased risk of stroke, which is high on the list of things I'd personally like to avoid, for whatever that's worth.

      I notice everything you quoted was from the link in my older article from five years ago. I can hardly be responsible for everything that guy said. In my text, I pointed out the small group ( (admittedly small at 100 people each) ) and I pointed out that the results weren't statistically significant. Of his article, my main takeaway was that this doctor changed his behavior because of it and other studies. I also thought that it offered a possible explanation for other things we've seen - such as the heart attacks of Jim Fixx and Alberto Salazar. Such small studies are most useful as an indicator of things that should get "real" studies. Full controlled, double-blind, studies.

      I also note you didn't list the conclusions of his that I think you agree with - about no magic foods, no magic supplements, no benefit to eating "fruits and vegetables", gorilla levels of fiber and the rest. Those are in my piece from 5 years ago, toward the bottom. The magazine link today appears different than the article that was there five years ago.

    3. I do agree with your point about no magic foods etc.

      A friend of mine had a son die suddenly in a school basketball game. His major artery ruptured. Both parents blamed themselves and sports. But eventually they were told by a doctor that their son and even themselves were susceptible to this sudden death and the physical characteristic associated with it was abnormal height and large hands etc. For years it was thought it was the physical activity. One thing the doctor told him stuck in my memory; that it could have happened to his son while taking a bowel movement or almost any physical activity. It is easy to jump to conclusions about cause and effect. Correlation does not imply causation.

      My grandmother used to tell me not to put sugar on my cereal as it would gibe me "sugar diabetes". My mother would tell me not to go out in the cold with wet hair as it would cause pneumonia. Then there is the famous: "don't cross your eyes they will get stuck like that". So much of what we think we know about health and what is healthy is simply incorrect or incomplete.

  8. Kinda funny. I just posted an article about how serious, fast, joggers' long term health is as bad as the folks who don't exercise at all. While the casual, light, joggers had the best health of the group. It was all I could do to not wave it n the faces of my crossfit friends!

    1. Yeah, it's starting to get a bit more study and a bit more coverage.

      I had to chase down your blog and find the piece, but interested readers who come across this will find it here. A quick look shows it's from the Journal of the American College of Cardiology and involved 1100 joggers and 4000 non-joggers. Just getting to a good sample size. Bigger is always better, but it's just not feasible to get 50,000 people for everything a researcher wants to look at.