Are High-Intensity Workouts Safe?

The Time-Crunched Cyclist reveals the fastest way to get fit for bike rides and races of all kinds. With elite cycling coach Chris Carmichael’s innovative, time-saving approach, busy cyclists will develop fitness, speed, and power in just 6 hours a week.

Here’s a question from the book that Time-Crunched athletes ask often.

Q: Are high-intensity workouts safe? Are intervals going to kill me?

A: Last summer I rode the 78-mile Copper Triangle event with my teenage son, Connor. It was his longest ride ever, in mileage, elevation gain, and time on the bike. He did great, and I loved sharing the experience and the day with him. As we both climbed Vail Pass with our hearts pounding away, I thought about the “Cycling to Extremes” article in VeloNews magazine and similar articles that have asked the question of whether high-intensity training is dangerous to the hearts of athletes, particularly athletes above the age of 40. It’s a sub­ject people ask about frequently, so, after consulting with cardiologists, cardiac surgeons, and electrophysiologists, here are my thoughts on the matter.

If you haven’t read the VeloNews article, the quick summary goes like this: Some endurance athletes develop atrial fibrillation (AF, an electrical problem in the heart that causes atria to quiver instead of pumping blood properly), myocardial fibrosis (stiffening and thickening of the heart muscle), or tachy­cardia (an abnormally high heart rate that may feel like your heart is skipping a beat). [Related post: The Early Warning Signs of Arrhythmia] The question is whether long-term participation in endurance sports increases an athlete’s risk for developing these conditions, and the article leans heavily in the direction that it does.

[Related book: The Haywire Heart by Chris Case, Dr. John Mandrola, and Lennard Zinn]

This is obviously a cause for concern for many athletes. I’m 56 years old and I’ve been training and competing since I was 9. What did I do after read­ing the article? I went for a bike ride, complete with intervals, and I was far more worried about getting run over by a distracted driver than about poten­tially damaging my heart.

The physicians I’ve consulted generally agree with me. On balance, they believe the health benefits of exercise—including strenuous exercise—out­weigh the risks of developing electrical or structural problems within the heart by a large margin. That’s not to say the risk isn’t there, but rather that exercise is only one of many factors that contribute—positively and negatively—to the health of your heart.

But that’s not really news. Everyone knows that some exercise is better for you than none, and for the people reading this book, the choice is not between your current training workload and nothing at all. You’re not going to hang up your wheels and just sit on the couch. What athletes struggle with is whether the choice is between strenuous exercise and a more leisurely level of activity.

Cardiac Problems Are Extremely Rare for Time-Crunched Athletes

In the past 16 years, CTS coaches have worked with more than 17,000 ath­letes, the vast majority of whom fit the profile of a time-crunched athlete. We are neither physicians nor medical researchers, but in that time we know of only a handful of athletes who have developed heart rhythm issues, structural heart issues, or suffered a heart attack or stroke while exercising. For example, throughout our coaching programs, our athletes have the opportunity to put a medical hold on their membership, and when they do so we ask them about their medical condition. Few have cited heart issues as a reason to suspend train­ing. Similarly, when athletes stop working with CTS, we always ask why they are leaving. As part of our quality assurance program we also ask the coaches for information about athletes who cancel. The few athletes who have developed AF were open and eager to tell us, which leads me to believe other athletes would be similarly honest and forthcoming. Yet we are not seeing any increase in the number of athletes reporting arrhythmias or other cardiac problems.

CTS is one of the largest endurance coaching companies in the United States. The vast majority of the athletes we coach are men between the ages of 40 and 65. Some have been training consistently for 30-plus years while oth­ers are relatively new to endurance sports. All of them do interval training. If years of cumulative endurance training—including high-intensity train­ing—were leading to a significant increase in arrhythmias in athletes over 40, I would expect we would be one of the first organizations to see it happening. It would be troubling and noticeable if more and more athletes were requesting medical holds or canceling or dying because of cardiac health problems. But we are not seeing that.

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The Time-Crunched Cyclist reveals the fastest way to get fit for road racing, century rides, gravel grinders, cyclocross, Gran Fondos, and mountain bike events. With elite cycling coach Chris Carmichael’s innovative, time-saving approach, busy cyclists will develop fitness, speed, and power in just 6 hours a week.

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