Exercise – it might not add years to your life, but it adds life to your years.
Amby Burfoot (1968 Boston Marathon winner)
My family history includes heart disease and early cardiac-related death, so running literally has been a lifesaver. Since I started running, I’ve lowered my (bad) cholesterol, lowered my triglycerides, lowered my blood pressure, lowered my heart rate and lowered my weight. I’m healthier, right?
Not so fast, some doctors now say. All of that running may not be so healthy, after all. Splashed across the front page of the The Kansas City Star was a headline warning that too much running – as in, the amount of running I routinely do on a weekly basis – can kill you.
This is what, in my newspaper days, I would have called a “man bites dog” story. It’s newsworthy because it’s paradoxical and surprising and counterintuitive. And, I would add, sensationalistic and misleading.
A study reported in this month’s issue of Missouri Medicine compared the build-up of arterial plaque in 50 runners (who had run one marathon a year for the past 25 years) with an average age of 59. They found that 30 of those runners had plaque build-up. They compared these marathoners with a control group of 23 non-runners, also in excellent health, with an average age of 55. (Why was this group so much smaller and younger? Shouldn’t a control group be the same size and age?) Just as many non-runners had arterial plaque build-up. What raised red flags was the fact that the marathoners seemed to have larger plaque volume. Could too much running be the cause?
This news put marathoners in a real quandary. On one hand, we tend to obsess over statistics and studies. On the other hand, we tend to be stubbornly independent and don’t care much what other people tell us, anyway. We’re used to people thinking we’re crazy.
Is too much running too much of a good thing?
It’s important to point out, first of all, that this study did NOT compare mortality rates. The study looked at one measure of heart health. Artery plaque is a significant risk factor, of course, but there’s no way to predict with certainty who, among either group, might have a heart attack. We don’t know who will actually live longer, the runners or the non-runners, because the study didn’t address longevity. It simply reported on the prevalence of one indicator in isolation from a host of other factors. As far as I know, all of the study participants are still alive and well (and running). It might be interesting for researchers to continue following these subjects and, at some point in the future, report back to us about which group actually lives longer.
My money is on the marathoners.
Also important to point out is that other experts have stepped forward to dispute the study’s conclusions.
A Wall Street Journal article notes that “many cardiologists are skeptical.” For example, Aaron Baggish, a Massachusetts General Hospital cardiologist (and marathon/triathlon athlete) is quoted:
“The science establishing a causal link between vigorous exercise and coronary disease is shaky at best.”
Ah, the “causal link.” It’s always difficult to link cause and effect. Just because two factors are present doesn’t automatically mean that one factor caused the other. One study is insufficient to demonstrate a cause-and-effect link.
I might just as credibly argue that, since the study apparently enlisted only Minneapolis-St. Paul-area runners, the cause might be something in the Minnesota water. (My assumption is based on the fact that they ran the Twin Cities Marathon every year for 25 years.) Or it might have something to do with the surprising fact that most of the marathoners were former or current smokers (52 percent of the marathoners vs. 39 percent of the non-runners).
The authors of the study (which I have completely read and partially understood) seem to tacitly admit as much. They concede that a definitive study would need to begin with a group of individuals randomly assigned to start running marathons for 25 years, while another group of individuals would be randomly assigned to remain sedentary for 25 years. Such a study is “practically impossible, and will never be done,” they rightly lament.
Without such a study, however, they have to admit:
“Thus, a cause-and-effect relationship between marathon running and accelerated coronary plaque development cannot be established.”
Whoa … didn’t they just concede the entire premise of their conclusion?
Amby Burfoot reported in a Runner’s World article:
“This clearly was not an outcomes study,” principal author Robert Schwartz told Runner’s World Newswire. “In the general population, coronary calcium is unequivocally the best predictor of cardiac events, but is the same true for marathoners? No one knows. There’s simply no data now. We need followup studies over time to get the answer.”
Seems some of the study’s authors are not nearly as adamant in their conclusions as the newspaper headlines portray. Burfoot also quotes study coauthor William Roberts, who’s also medical director of the Twin Cities Marathon:
“When the sedentary group starts shoveling snow or racing after a bus, they’re going to be at much higher risk than the runners. We don’t see marathon runners dropping dead on a regular basis at Twin Cities. I’d rather be a marathoner than one of the sedentary guys.”
Alex Hutchinson, unlike yours truly, is qualified to debate this head-to-head with researchers. Hutchinson is a former physicist and national-class runner, and a National Magazine Award-winning science journalist. He delves into the details of this and similar studies and examines the science. And he remains unpersuaded. Hutchinson argues that they are drawing conclusions that aren’t supported by the data.
Risks & Rewards
Bottom line: In running, as in everything else we do, there are risks and rewards. We measure the risks and compare the rewards to determine whether marathon running, or playing tennis, or skydiving is a suitable activity.
I still believe the rewards of marathon running far outweigh the potential risks.
Let’s assume this study is correct, that marathoners might be more likely to die from heart problems caused by arterial plaque. Nevertheless, we are a lot less likely to die from a much longer list of health problems caused by being more sedentary or overweight. The odds are still in our favor.
Running: Magic Pill Or Loaded Gun? Neither!
Natalie Diblasio, who blogs at Runner’s Breakfast, reminded me of a recent Runner’s World report about a study of Boston marathoners to determine if excessive exercise causes atherosclerosis – a disease in which plaque builds up in your arteries. She writes:
The study used 42 Boston Marathoners who had been running for 12 years, on average, and trained about 40 miles a week. The control group was their spouses – selected because they share many of the same lifestyle habits.
The result? There was no difference between the two groups.
“This should be reassuring to marathoners,” says Beth Taylor, Ph.D. told Runner’s World. “Our study suggests that while endurance running is not a ‘magic pill,’ neither is it a loaded gun. To optimally modulate their cardiovascular health, runners need to continue to focus on diet, stress reduction, other risk factors, and regular checkups.”
The study did find some pros for marathoners. The runners had significantly lower body weight, significantly lower resting heart rate and significantly lower BMI.
But the rewards of running transcend physical fitness. Some things can’t be measured by a scale or detected in a doctor’s office or quantified in a research study.
- Rewards of running: emotional, spiritual, and mental health.
- Rewards of running: quality of life, enjoying the outdoors, socializing with a diverse group of like-minded friends.
- Rewards of running: releasing stress, having fun, feeling the rush of endorphins, enjoying a level of fitness that improves our performance in other endeavors.
- Rewards of running: the self-confidence gained by setting and achieving goals, the sense of accomplishment earned by pushing yourself to run farther or faster, the thrill of crossing the finish line.
Risks of running include being bitten by a dog, or hit by a car, or (these doctors say) suffering arterial plaque build-up.
I’ll take those rewards over those risks any day.