New book: Too much exercise can hurt the body’s most important muscle

“Haywire Heart” provides research, case studies

by Mike Ivey

I still remember when I realized something was seriously wrong.

It was the day after my birthday five years ago and our regular Sunday morning group was rollerskiing on a country road near Cottage Grove.

Within the first 15 minutes I’d already fallen far behind and was short of breath. My buddies had to wait up for me and one of them joked I must have had one too many the night before.

“No. I’ve skied with a hangover before,” I said. “This is way different.”

On their advice, I cut the workout short and headed back to the parking lot. The next day I called my doctor who told me to come right in.

I explained to my MD that I’d been feeling gassed the past few weeks when I tried to do anything aerobic. Even going up stairs left me breathing hard—scary stuff for someone who thought they were in pretty good shape for an aging baby boomer.

So he listened to my heart. “You’re missing some beats,” he said. I was then hooked me up to an electrocardiogram machine which confirmed my heart was badly out of rhythm.

Unfortunately, it’s become a familiar story for many people as they continue to train hard into middle age. Spend much time around serious endurance athletes these days—the kind who do Ironman triathlons or take 100-mile bike rides—and you’re bound to hear stories about heart problems.

There is a growing body of medical evidence suggesting a lifetime of aerobic exercise can indeed cause heart arrhythmia, a serious condition where the four chambers of the heart are not beating in the proper sequence. I can personally name a dozen friends and competitors dealing with arrhythmias of one sort or another.

Given that we’ve been told for years that exercise is good for you, it seems counter intuitive to think it can actually mess with the proper functioning of your heart. If you’re looking to set a PR in a marathon or just keep up with your pals on the next bike ride, you need that heart working as efficiently as possible.

But studies are showing that long hours of training over decades can indeed change the physical makeup of the heart muscle, throwing off the complicated electrical system that keeps it working properly. Some reports even claim endurance athletes are five times more likely to develop an arrhythmia than the general population.

A new book titled “Haywire Heart” does an excellent job of walking the line between alarmism and reality. It’s co-written by Lennard Zinn, a former U.S. national cycling team member and American Birkebeiner skier; John Mandrola, a cardiac doctor and lifelong runner and cyclist; and Chris Case, managing editor of VeloNews, a sister publication to VeloPress, and author of the article “Cycling to Extremes” that brought the heart issue to national attention.

The Haywire Heart by Lennard Zinn, Dr. John Mandrola, and Chris Case

You don’t usually die from a heart arrhythmia but the condition can lead to strokes or even cardiac arrest in the most serious cases. Atrial fibrillation, or “AFib,” is perhaps the best known since there are lots of TV ads currently touting a blood-thinning drug used to offset the increased stroke risk from it.

Still, exercise-induced arrhythmia is a tricky issue for health officials given the nation’s growing obesity epidemic. The multi-billion-dollar fitness industry also doesn’t want to broadcast that a lifetime of working out could cause some serious heart problems.

Both Zinn and Mandrola have experienced heart rhythm problems that have caused them physical and emotional distress. Serious athletes are often the kind of people who like to drive themselves harder than they probably should. They learn to suffer and learn to love the suffering.



To that end, the book takes special aim at those who may not want to hear the news or think they aren’t hurting themselves with obsessive exercise. The authors aren’t worried about retired Tour de France pros but rather than the weekend warriors.

“It’s the middle-aged people who think they’re training to race the Tour who can’t seem to stop themselves from pushing so hard for so long,” they write.

The 309-page book from Boulder, Colorado-based Velo Press in is certainly the most exhaustive look yet at the issue. It includes chapters on heart function and physiology that even the authors admit might be more information than most readers need.

But where “Haywire Heart” really shines are in the case studies of citizen athletes who have seen their lives turned upside down because of heart arrhythmia. For many of us, things like biking, running or cross-country skiing aren’t just ways to stay in shape. They become a focus of our social lives and a defining part of who we are.

The book acknowledges there is no simple answer to avoiding exercise-induced arrhythmia or dealing with it once it develops. Reducing the volume and intensity of exercise is the best antidote, the authors suggest, along with staying hydrated, watching the alcohol and eating a healthy diet. I was also glad to read about new medical evidence saying caffeine is not a trigger for heart rhythm problems as once thought.

In my case, I was lucky to get relief from a cardiac ablation, an increasingly common procedure where the bad electric circuit in the heart is cauterized to deaden the offending nerve cells. Since then, I’ve returned to biking and skiing, albeit at a lower level of intensity. I’m a tourist more than a racer these days.

The bottom line—and the real takeaway from “Haywire Heart”—is that moderation is indeed the best policy. Reducing stress, taking care of those you love and keeping your goals in perspective is advice we all should follow no matter our chosen pursuit.

Put another way, if you’re sweating it you’re likely trying too hard.

Mike Ivey writes the Footloose blog for


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‘Fast After 50’ Offers High-Intensity Training Advice

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Editor’s note: This is an excerpt from the new VeloPress book, “Fast After 50,” by Joe Friel.

Research tells us that the performance decline we typically experience with aging has a lot to do with how active we are while growing older. For example, a paper released in 2000 examined the combined effects of age and activity level over time. The researchers reviewed 242 studies comparing aging and VO2 max involving 13,828 male subjects. Each of the subjects was assigned to one of three groups based on how active they were: sedentary, moderately active exerciser, or endurance-trained runner. Aerobic capacity was highest in the runners and lowest in the sedentary group. No surprises there. The aerobic capacity changes per decade of life were sedentary, 8.7 percent; active, 7.3 percent; runners, 6.8 percent. What this means is if, at age 30, a man had a VO2 max of 60 and then for the next 30 years didn’t exercise and lived a “normal” (sedentary) life, he could expect his aerobic capacity at age 60 to be around 46. If he was moderately active, it would be about 48. And if he trained as an endurance runner, it would be in the neighborhood of 49. Those are not significant numeric changes. But for normal folks who generally see VO2 max declines of 10 percent and greater for a 10-year period, these numbers are really high.

But regardless of the actual size of the change, here’s the main message: The study further reported that the subjects who were endurance-trained runners significantly decreased their volume (miles run per week) and training intensity as they got older. That’s a common practice with aging athletes. So maybe it’s not simply working out that maintains aerobic capacity and therefore, in part, race performances; instead, it is how much training you do and how intensely you do it.

Yes, I realize that I am repeating the same message from earlier chapters in “Fast After 50.” It’s a critical lesson for getting faster regardless of your age.

How to Maximize Training for the Part-Time Skier

By: Scott Loomis

This past season marked my last year as a full-time cross-country ski racer. After eight very worthwhile years of racing and training all over the world I have decided to move on to a new phase in my life. Whether that next phase involves working as a roadie for the next Van Halen world tour, joining the World Horseshoe Throwing circuit or attending graduate school only time will tell.

In the meantime, I am working 40 hours per week in Park City, taking two classes at the University of Utah and working a second job one day per week at a local hospital. All of this leaves me very little time for any sort of structured ski training. In fact, I am lucky if I can squeeze in three to five workouts each week.

I do not plan on completely abandoning the sport that I have spent so many years immersed in. After you spend so much time working towards something you love, it becomes hard to simply quit cold-turkey. I do hope to at least remain competitive on the American Ski Marathon Series next season. But how do I get to a competitive level on such a limited training schedule? What I have decided is that I need to figure out how to maximize my training as a part-time ski racer.

I recently read a short article on the internet about how Thomas Alsgaard is currently training three times per week in his preparation for next year’s World Cup circuit. It would be nice if we all had the time (and insane physical capacity) to do this, but for those of us that are part-time racers and weekend warriors that work full-time and/or have families, we simply do not have enough hours in the day to do this. So the question is: What can we do to maximize the training we do have time for? What aspects of a training plan are most important? What can be left out or skipped?

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No matter how little time you are able to devote to training, you should always fit in one intensity workout every week to ten days starting in the summer. Maintaining that ability and feel of going hard throughout the year is important since it can be very difficult to regain once you have lost it. This is especially true the older you get.

Remember that an intensity workout can come in almost any shape or form. It doesn’t have to be something done on rollerskis or involve skiwalking or bounding for a specific amount of time with a specific amount of rest. It can be as simple as going hard for twenty minutes in the middle of an hour long run or bike ride or even trying to mow your lawn in world-record time. I personally like doing track workouts because I feel that I am able to get a lot of out of them. I am able to fit a bunch of short intervals into a relatively small amount of time and by the end of the workout I feel pretty tired. It is also a matter of convenience since there is a track right down the street from my house.

The point here is to periodically get your heart and lungs into hammer-mode……how you go about doing this really doesn’t matter all that much, especially during the summer. It’s not like your cardiovascular system knows what type of training method you are doing, all it knows is that it is working hard.

One good over-distance day is second on my list. It is amazing how well an occasional OD can maintain your endurance. If you average 45 minutes per workout, try to fit in an easy 2 hour over-distance day. If you average 1 to 1.5 hours, try to fit in a nice 3-hour outing. Again, don’t forget about the variety of training methods out there. A long kayak can be just as effective as a long mountain run. Also, try combination workouts, where you bike and run or rollerski and run, etc.

Unless you feel that your upperbody is your weakest link or you need to bulk up those beach muscles for that week on the houseboat in Lake Havasu, skip the trips to weight room during the summer. Some of you may disagree about this, but remember, I am talking about maximizing training on a limited schedule. Of course, if you have a lot of time to devote to ski training, consistent weight workouts can be a valuable supplement to your plan. If you like to rollerski during the off-season, throw in some double-pole only workouts and make those your strength workouts.

Weight training is really only beneficial if you are able to keep up with it on a weekly basis. So, I feel that it is best to start doing some in the fall and try to be consistent with it until you get on snow. I personally hate hanging out in the weight room. I would much rather go for a run than do sets on the bench press any day.

For those of you that really need to improve your upperbody strength I suggest that you make a small investment in turning your garage into a Rocky Balboa old-school training gym. A padded mat, a couple of 25 lbs barbells and wooden box for dips and step-ups is all you need for a basic strength workout that is right there at home. You could even add a punching bag since it just looks cool hanging there and it makes you feel tough.

For some of you, doing intervals may be unappealing and you really don’t have time for OD workouts either, so training only consists of “everyday” workouts. These are simple workouts where you just head out and run or bike or whatever at a comfortable pace for the time available to you. If you are only able to train for 30 minutes three times per week, make sure that you are getting something out of them. Going at a level 1 pace for 30 minutes really doesn’t do a whole lot for you, unless you are out of shape and just getting back into training or using it as a recovery workout. If you make some of these short workouts more like semi-pace workouts where you are training in your level 2 to 3 zone then you will get much more out of these days.

The main point I want to get across here is the importance of maintaining a good fitness level throughout the year and it that doesn’t necessarily matter how you get it done. If you are able to throw occasional intensity and over-distance workouts into your training throughout the summer and fall, then you are going to be much better off come ski season. Have a great year see you at the race.