Is Cycling Killing Us?

[Sig Isaac]

Brian Sinclair posted this link to a Velo News health article back on July 29:
http://velonews.competitor.com/cycling-extremes
(Cycling to Extremes: Are endurance athletes hurting their hearts by repeatedly pushing beyond what is normal? by Chris Case)

Brian's low-key subject heading, “A good read”, generated no response and few views. After having read the article and feeling like I had been hit by a truck, I thought I would try to revive the topic and maybe help stimulate some discussion and debate with a more sensational headline to get some attention.

The article examines the troubling number of older long-time endurance athletes showing up with heart rhythm problems, most notably atrial fibrillation (AF) and multifocal atrial tachycardia (AT). One study mentioned in the article suggests that there is a five-fold increase in the risk of developing AF with long term athletic activity. If you read the article you can see how serious these conditions can be and how they can effectively end one’s ability to train hard. Here is a sobering passage from the article that sums up the issue:

The more you ride, the harder you ride, the faster you ride, the better athlete you might become today. But over decades of exertion, the myocardial cells of the heart begin to simply fall apart, and you’re left with an unhealthy ticker. Or so these new studies suggest. When you’re 20, or even 30, this can lead to acute reversible injuries — temporary damage that can be relieved with correct rest. In a 50-year-old, repeated hard doses of the sport you love, the rides you cherish — since complete recovery doesn’t occur as efficiently — could be leading to accelerated aging, or hypertrophy — in layman’s terms, a stiff muscle in your chest. That probably wasn’t what you were looking for when you bought your last bike. One of the more telling research papers on the subject, published in 2011 in the Journal of Applied Physiology, studied the structure and function of the heart in lifelong competitive endurance veteran athletes, ranging in age from 50 to 67. MRI studies revealed that some 50 percent of the veteran athletes had myocardial fibrosis, a condition that involves the impairment of the heart’s muscle cells, called myocytes, through hardening or scarring of tissue. In age-matched controls — people of the same age who didn’t compete — and young athletes, there were zero cases of the disease. Furthermore, the fibrosis was significantly associated with the number of years spent training, and the number of marathons and ultra-endurance marathons they had completed.

I think it would be healthy to have a discussion about how much of a risk heart arrhythmia poses to the typical Tripleshot rider, and perhaps gain from other peoples' experiences and insights. Some questions to consider:
o Should this even be a concern compared to all of the other risks of riding, such as getting hit by cars or crashing?
o What is too much training? Is riding 8-15 hours a week at all risky?
o How much time do we need to recover?
o What can we do to minimize our risk of developing arrhythmia?

I look forward to hearing your thoughts.

[Robgrant]

Well, I don't ride enough to be within the 'affected' group. I suggest we consult our resident skeptic- Mr. A Cassels?
I would rather read the original study (s) than the article based on the study. Journalist sometimes are not as scientifically literate as we would expect.
RG

[barton bourassa]

"repeatedly pushing beyond what is normal". Ok, what is normal? I don't think what elite athletes do is normal. That is why they are elite. Do they all die when they turn 50 if they don't stop doing what is not normal? Is this article talking about elite athletes, a minuscule % of our population? Or is it referring to us middle aged men and women who train and push and occasionally really stretch the boundaries?

I know my wife is always concerned about my physical activity and has often referred to it as extreme. I have constantly checked in with my family doctor. He does not seem to feel there are any long term problems with level of physical activity. Only long term problems he sees are continued ridiculously low cholesterol, a strong heart and great blood pressure limiting his ability to prescribe pharmaceuticals. He is aware of the extent that I go to in training and the extreme level I have pushed my self during events (I used to call them races in a younger era!) that take place about twice a year. It is interesting to me that it appears to be my legs that give out far sooner than my lungs or heart! I end up with severe cramps near the end of these events then watch as my heart rate falls as my effort decreases and I limp to the finish. I'll check in with my doc next time I see him but I think that I have more a mental or psychological issue than one of the heart.

I have never had much faith in medical journalism. I'll keep riding; keep pushing well beyond what is normal for me; keep checking in with my doctor. I'll continue to live. Fortunately, I am not and never have been an elite athlete!

BB

[Bosie]

I think this is an interesting article and raises a number of good questions- none of which have a good answer.

So here is my 2 cents worth- I spend my non biking hours as a cardiac anesthesiologist playing with cardiac physiology and dealing with the problems described in the article.

As regards the study: The study quoted suggests that a population of people who engage in extreme endurance sports may have a negative effect on their collective hearts- some myocardial fibrosis. BUT as an individual, this is very hard to quantify. Is it possible that those who dont end up with myocardial fibrosis or Arrhythmias actually have better hearts? Is a small amount of myocardial fibrosis seen on MRI clinically significant? Is it even bad for you, or is it a normal response to exercise? Without seeing the actual study, its hard to know. (perhaps Ill look it up) (And this is where Alan can get on his podium- a lot of sensitive medical tests find things which seems like a "bad" things, but often are normal and certainly have limited clinical consequence.Treating these things lead to more harm than good- but I digress:) )

Not having myocardial fibrosis (possibly) or an arrhythmia, however, is a tiny (but dramatic- and hence newsworthy) fraction of the sum total of "stuff" that makes up good "Health". Even cardiac health.
So, whilst engaging in "extreme" physical activity, might predispose you to arrythmias and even death from such an arrhythmia, the other benefits are likely, IMHO, to far outweigh that risk.

Physiologically and Psychologically the added benefits of consistent exercise are undeniable. Muscle mass, weight, activity,Lower BP etc.(all products of exercise) all correlate very positively with longevity and health. (whilst extreme endurance exercise probably doesnt).

Whilst there is some risk to be an extreme endurance athlete from a cardiac point of view, I would suggest that the risk of crashing your bike (and dying from that ) is probably MUCH higher (Anecdotally- How many people do you know if this year who have died while riding their bikes from an arrhythmia (dropped dead) and how many from an accident?)

Bottom line, I think you are pretty safely on the side of a net positive benefit to your health and well being when cycling consistently. Taken to extremes, it might be bad for you, but dropping dead doing something you love and enjoy is a good way to go.....

[jj12]

[Bosie]

Found the study:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3119133/

Small sample size.
2 of the 6 with myocardial fibrosis probably had it from either Coronary artery disease or myocarditis (unrelated to sports) (and if you took them out, there might no longer be any significance?). The other 4 had between 1 and 3 % fibrosis which seems tiny.
Lots more to criticize, but you get the picture...
PS: read the description of what they regarded as endurance athletes...

So call me even more skeptical- I'm underwhelmed by the study..

[Brian S]

As I said--an interesting read, and I was posting purely from the perspective of the article as general interest, but not with the intent of debating academic rigor. It was a small study. but I though quite elegant from an imaging perspective. Now, a lot has happened since that study was published almost 5 years ago. Without a doubt we have an effective 'window' of endurance activity and aerobic fitness having a protective effect, and in some cases where there may be an underlying predisposition, a risk for myocardial stress/damage/atrial arrhythmias. Now remember, I am a pediatric cardiologist, and the vast majority of this club are waaaay beyond my primary care group.

Here, again from a generalist discussion perspective is an abstract from a recent review

CURRENT OPINION Cardiology 2015
Atrial fibrillation and the athletic heart
Calum J. Redpatha and Peter H. Backxb
Purpose of review
Endurance exercise, despite a plethora of proven health benefits, is increasingly recognized as a potential
cause of lone atrial fibrillation. Moderate exercise reduces all-cause mortality and protects against
developing atrial fibrillation. However, more intense exercise regimes confer modest incremental health
benefits, induce cardiac remodelling and negate some of the cardiovascular benefits of exercise. The
implications of endurance exercise and athletic heart are becoming increasingly relevant as the popularity
of endurance exercise has increased 20-fold within a generation.
Recent findings
An apparent dose–response relationship exists between endurance exercise and left atrial dilatation.
Repeated strenuous endurance exercise overloads atria, resulting in stretch-induced ‘microtears’,
inflammation and endocardial scarring. Although these findings are observational in humans, similar
mechanisms have recently been confirmed in animal models suggesting causation.
Summary
Currently, it is not known whether a ceiling for endurance exercise exists, and, if so, what factors
determine the threshold of harm. Although preliminary research is promising, much work remains if we are
to understand the mechanisms underpinning atrial fibrillation in athletes.
Keywords
athlete’s heart, atrial fibrillation, endurance exercise, inflammation

[Brian S]

PS--Sig, thanks for bringing this back to the top of the list!

[Marcus]

As person who experiences SVT, rapid heart rate from time to time I have a theory, all parts wear out eventually, especially British designed electrical systems or as the Yogis say a heart only has a fixed number of beats in one lifetime. So 10 hours a week of cycling will generate 10 hours x 60 minutes x 100 extra beats per minute and I will die 60,000 beats per week sooner than if I did not cycle but wait by cycling I have also reduced my resting heart rate by 10 beats per minute so as I rest I will save 158 hours x 60 minutes x 10 beats per minute and live 94,800 beats per week longer and prosper. So keep on cycling, it's good for you, to a point.

[Scott Davis]

In October there is a medical team coming to Victoria to perform Masters Athlete Heart Health Testing. The study information is at the link below.

http://tribc.org/uploads/files/2015%20D ... esting.pdf


They're looking for old guys (and gals) like most of us. It would be a good way to get educated.

Keep riding,

Scott

[Fozzy]

What about the effects of the copious amounts of post ride coffee?

[barton bourassa]

Marcus, live long and prosper with that wonderfully low heart rate.

By the way, good luck on your European Mountain adventure!!

Barton.

[Sig Isaac]

Great discussion -- I was hoping that there would be some in-house experts and people with personal experience on the matter and I wasn't disappointed! A special thanks to Craig, Barton, Brian and Marcus for their views. Two years ago I had never heard of atrial fibrillation in relation to long-term training; now it keeps popping up in the media and in conversation. A couple of athletes I have known have been diagnosed with it. I don't like to live in fear and I won't, but it would be good to know the available facts and make reasonably informed decisions about our health. I think we will be hearing a lot more about exercise induced cardiac arrhythmia in the future. Medical opinions will probably be all over the map for a while, but hopefully a meaningful understanding of the risks and preventions will come to light.

I agree with Bosie that dropping dead on your bike would be a good way to go (hopefully while winning a KOM), but I sure wouldn't want to be the poor guy in the article, Mike Endicott, who has to live with an implanted defibrillator that shocks his heart back into submission with what feels like lightning bolts. Even worse, he can no longer pursue his passion to train and compete.


See you at the sprint workout tomorrow. Bon Courage to Marcus -- it will take you years to earn back all of the extra heartbeats you will be expending at the Haute Route.

[Bosie]

Thanks again to Brian and Sig for bringing this topic up.
Ive enjoyed the discussion as well.

I tried to register for the talk mentioned in Scott's post, but it only seems to be in Kelowna- Scott, do you know if they are giving the talk here as well?

Craig B.

[Brian S]

and as someone who is recovering from replacement of a worn out part, hips are easier than hearts, but take care of both
Here is the link to the Sports Cardiology study ( I think this is the one referenced)

B

http://www.sportscardiologybc.org/news/ ... -victoria/

[Bosie]

Along the same theme an interesting article on the negative effects of extreme exercise:

http://www.theguardian.com/lifeandstyle ... ke-you-ill

[StanV]

Thanks for keeping the thread alive until my return from holidays.....now my 2 cent's worth.

I am a relatively new member, many won't know me. Certainly not an "elite" athlete and never have been, but I am a colleague of Craig's with an interest in this topic because:
- I love riding my bike
- I am 56 years old
- I have had atrial fibrillation, total 4 times in the last 9 years

Though never an elite athlete (hockey in my youth) I began running at age forty. I embraced it, trained "hard" by most people's standards (club runner, coach, 3 hard workouts plus a long run weekly, at my peak 120-130 km/week). In 2006, in the best shape of my life with 3 weeks until the Boston marathon which I had trained for, I developed atrial fibrillation. Devastating at the time....
My cardiologists were not athletic types and had no info for me. On my own, I found the above article as well as a retrospective study of middle-aged Swiss men who pursued endurance sports. The association was suggestive. My own echocardiogram demonstrated typical "athlete heart" findings. And for completeness, I had a family history of AF.

So, I did a couple of things: I did run Boston, but at a pace slower than my goal (parenthetically, I never again pinned on a race bib except to accompany a friend, because I discovered how much fun it was a little bit back in the pack). I then deliberately "de-trained" to a point where I could still enjoy running, but gave up my watch, my "hard runs" were spontaneous rather than planned. I have had three AF episodes since, but their frequency is less than would have been predicted, and all but one occurred in the first two years. My follow-up echocardiograms have been "normal".
As Craig mentioned, you don't need a whole lot of exercise to reap the cardiovascular/longevity/improved quality of life benefits. I simply asked myself "Why run?", and adjusted my goals and activity accordingly.

Final twist - moved to Victoria in 2011, and in 2012 my "groin pull that wouldn't get better" was diagnosed as severe hip osteoarthritis. So now my bike is my exclusive exercise. And, I am still "detrained"...but, only relatively! I enjoy riding hard sometimes, I love climbing a hill, but I won't push the training really hard. In some ways that might increase my risks, but they are still low, and worth it for the joy of riding, conversation, coffee, etc.
And yes, cars and crashes are still way higher on my "things to watch out for" list.