From The Desk Of Clarence Bass
“Many endurance athletes are damaging their hearts by repeatedly pushing to extremes…particularly in those who continue to strive for more as they enter middle age.” The Haywire Heart: How too much exercise can kill you, and what you can do to protect your heart (Velo Press, 2017)
Too Much Endurance Exercise For Too Long Can Kill You
I’ve written before about the dangers of too much endurance exercise (the association with irregular heart rate), but it has been based on short pieces or individual cases. We now have a book that spells out the dilemma from start to finish—and explains what can be done to avoid or treat the problem. A difficult task when you consider that the victim group is small. Not many endurance athletes have heart problems. The dose of exercise that promotes health is small and easy to prove. On the other hand, how much it takes to causes heart problems is hard to nail down and study. Blind randomized controlled trials are impossible. Less rigorous types of research must be relied on.
The Haywire Heart is the most comprehensive guide to date on the subject of endurance sports and heart health. It’s primarily based on observational and animal studies. The authors also makes good use of case histories. Each of the nine chapters concludes with a real life case study.
Another plus is that each of the three authors, all lifelong endurance athletes, come at the issue from different vantage points.
Chris Case is the managing editor of Velo News and author of the groundbreaking article “Cycling to Extremes” that brought the problem of the athlete’s heart to national attention. A runner from the age of 12 and a competitive cyclist, he has a degree in neuroscience and has conducted clinical research.
John Mandrola, MD, is a cardiac electrophysiologist, who frequently writes and lectures on the subject of endurance and heart health. He has been a competitive athlete much of his life and has personally experienced a rapid and irregular heartbeat.
Lennard Zinn is a lifelong endurance athlete and a former member of the US national cycling team. His personal story of multifocal atrial tachycardia inspired The Haywire Heart.
What is presented here barely scratches the surface of what you’ll find in The Haywire Heart--basically the bookends: A condensed and simplified overview of the supporting evidence and ways to protect against the disorder. I leave it to you to explore the remarkable detail marshaled by this committed, informed, and thoughtful team.
Again, I want to emphasize that endurance exercise is almost always good for the heart. Problems occur only in a “tiny fraction of elite athletes,” Dr. Mandrola relates. “The vast majority of endurance athletes do not develop …arrhythmias.”
“A mountain of data exists,” Dr. Mandrola reports. While it’s difficult to tease out, the evidence that “excess endurance exercise could cause AF” is there.
He begins with observational studies from Scandinavia. In 2009, researchers from Denmark performed a meta-analysis of six studies of 655 athletes and 895 control subjects. They found AF in 23 percent of the athletes and 12.5 percent of the controls. They concluded that being an endurance athlete increased the odds of having AF fivefold. (A summary of the studies in the book shows that the percentages varied widely.)
More recently, using data from a study of cross-country skiers 65 and older, Norwegian researchers found that athletes were 1.9 times more likely to have AF than controls. (The lower ratio was attributed to older subject and older controls.)
In 2013, Swedish researchers studied more than 52,000 finishers in a famous cross-country ski race over 10 years. They observed arrhythmia in 919 athletes. The two factors increasing the odds of AF were the number of times doing the race and a faster finishing time. Skiers who completed five races were 29 percent more likely to have AF than those who completed only one. Athletes with the fastest times were 30 percent more likely to have AF than those in the slowest group.
It appears that age and athletic excellence can be a toxic combination.
Mandrola then turns to an experiment with rats termed a “truly beautiful work.” (You’ll see why a biologist might think that. Don’t know about the rats, however.)
Canadian researchers trained male rats to run one hour per day, for up to 16 weeks. This regimen simulates decades of running in humans. Compared to sedentary controls, the exercised rats showed evidence of lower heart rate, atrial dilation, atrial scarring, and enhanced vulnerability to AF. (The atria are the receiving chambers of the heart. They contract and push blood into the ventricles, the pumping chambers. For a quick overview of heart mechanisms and the role of exercise: http://www.cbass.com/heartmechanisms.htm )
Importantly, detraining the exercised rats resulted in rapid reversal of heart rate and AF vulnerability. Scarring and atrial enlargement, however, remained after the rats stopped exercising.
Finally, they found that chronic exercise altered genetic components of the rat’s cells. Prolonged running altered the expression of their genes. (The process by which exercise can alter gene function is called epigenetics. See http://www.cbass.com/epigeneticSpecificity.htm )
“These findings have major implications for the effects of endurance exercise,” Dr. Mandrola explained. “The experiment reproduced many of the findings of the athletic condition, such as lower heart rates and dilation of the atria. The exercised rats developed scarring in their atria. Scarring plus dilation plus greater sensitivity to vagal [nerve controlling heart rate] stimulation provides the abnormal substrate needed to maintain AF in athletes.”
Dr. Mandrola also reports similar results in humans. Swiss researchers compared a random sample of 60 runners after a 10-mile race with a control group from the general population.
Separating the running group based on lifetime training hours they found that premature atrial contractions increased in parallel with lifetime training hours. Although this is a small nonrandomized study with self-reported training hours, Mandrola says it “moved in the same direction as the rat-training models.”
There’s more, but this is more than enough to establish the connection between chronic exercise and heart rhythm disorders.
“The finding that a reduction in training intensity and/or length often fixes the problem further bolsters the connection between prolonged exercise and heart damage,” Mandrola adds.
That brings us to the case study presented along with “The Evidence.” (You won’t want this problem.)
Mike Endicott was diagnosed at age 50 with a life-threatening heart irregularity. (What follows is the bare bones. You’ll find many more details in the book.)
Mike was burning the candle at both ends. He was working nonstop as a sales representative in four states and as a competitive athlete. Six months Nordic skiing and the other half devoted to road and mountain biking. “I was chronically overtrained,” he acknowledges. He lived this way for years.
One day in 2005, it came to a head in a Nordic skiing competition in Colorado. “Punched up over this rise and all of a sudden, I don’t feel good, something’s not right. Something was beating inside my chest. No pain, no discomfort, but I was a little dizzy.”
Soon he collapsed in the snow and began to die. By pure chance, two friends rescued him. It was a miracle that he survived.
“I did it all to myself—by personality.” He admits that he would probably do it all over again (with more rest and recovery).
That’s saying a lot, when you know what was to come.
He had three failed ablations before a fourth was successful. He would not only be awake for the procedures, but would be caffeinated and given intravenous adrenaline to improve the chances of inducing arrhythmia while he was on the operating table. Catheters were sent through his femoral veins and arteries, on both sides, and led into the heart. For his first attempt, he lay awake for eight hours and they still failed to identify the source of the arrhythmia.
The next attempt they tried for 16 hours and still couldn’t find the culprit.
Can you imagine going through that four times?
What could have been done to prevent this nightmare?
Rest and Protect
Push, push, push can damage the heart. Push and rest allows the heart time to adapt and repair. This hold true at any age, but it becomes more important as we age. As we move into our 50s and 60s, we need more rest after hard exertion.
“Aging muscles [including the heart] are more susceptible to exercise-induced damage and are slower to adapt and repair,” Chris Case observes at the close of The Haywire Heart.
That’s hard to accept for athletes who came of age believing that hard training is the best thing you can do for your heart. Mike Endicott admits that his biggest struggle was accepting that something he believed was the best thing he could do for himself had almost killed him. Chris Case drives that point home in the Epilogue:
The evidence we’ve presented in The Haywire Heart can be alarming. If you are a committed endurance athlete, you probably need to recalibrate your understanding of medicine and exercise to accept the fact that what you once thought was the best thing for your health can turn out to be the exact opposite, if taken to the extreme.
Happily, he adds that training hard and resting hard may not only add years to your training life and your actual life. “There’d a good chance it’ll make you faster too.”
Elite endurance athletes are not likely to look to people who training is all-out and brief for advice on training in the middle years and beyond. But the new awakening to the dangers of extreme training should be taken into account by those of us who do resistance training and high-intensity intervals.
A few years back I wrote about my return to lifting once a week: weights on day 1 and aerobics on day 5. That’s it. I do each form of exercise once a week, allowing four days of recovery after weights and three after aerobics. Both workouts are high intensity—short and hard. http://www.cbass.com/howmuchexercise.htm
The Haywire Heart lends credence to that adjustment. It also alerted me to a review study on the effect of aging on muscle recovery by Australian researchers James Fell and Andrew Dafydd Williams reported January 2008 in the Journal of Aging and Physical Activity. http://journals.humankinetics.com/doi/abs/10.1123/japa.16.1.97
While many studies show that aging muscles experience greater exercise-induced damage and a slower rate of repair and recovery, Fell and Williams suggest that not enough attention has been given to the benefits of training throughout the life span.
“Future research should…take the physical activity level of the participants into account,” they conclude.
It appears that we still have a lot to learn about the optimal balance of stress and rest as the years roll on. What we do know is that too much exercise can cripple or kill, especially in the middle years and beyond.
Rest and recovery become more important with the passing of time. Athletes in their 50s and 60s are especially susceptible to the dangers of overtraining. The few of us still training hard into our 70s and beyond are breaking new ground. We must listen to our body and train sensibly. Find an exercise minded doctor and have regular check-ups. Never forget, however, that you can help yourself more than anyone can help you; the exception is when you are critically ill.
Train hard and rest hard seems to be the best approach—at any age. If you’re going to err, do it on the side of active rest.
March 1, 2017
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