DALLAS — Dr. Chip Lavie says he has to wear body armor to races these days because of hostility from fellow runners, and he sounds like he's only partially kidding.
The medical director of cardiac rehabilitation and preventive cardiology at John Ochsner Heart and Vascular Institute in New Orleans is also co-author of two recent studies about running's potentially negative effects on the heart.
"People have written in heavily criticizing it," he says. "Obviously it's made people think."
The essence of the studies is of the good-news, bad-news ilk.
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Good news: Runners have a 20 percent lower mortality rate than nonrunners.
Bad news: People who run in higher doses — more than 20 miles per week, "which is not a whole lot," Lavie says — seem to lose that benefit.
"I thought you'd have lower mortality with running and at some point it would level off, and there would be no additional benefit," he says. "But I didn't think it would level off and head the other way. There actually seems to be a U-shape.
"At superhigh doses — marathon running, ultra-marathons, really long-distance bike races — there's actually potential for cardiac harm."
Though his own research has made Lavie, whose marathon personal best is an impressive 3:10, cut back a little, he still runs almost daily (except one day before a short race and two before a long one). As of right now, he's sticking with 5Ks, 10Ks and half marathons — not full.
"I'm not trying to scare people," he says. "I'm more interested in encouraging people to get the maximum benefit at lower levels. From a society standpoint, there's much more of a problem with lack of exercise than too much."
That seems to be the crux of local experts' message, too.
"First of all, we shouldn't use those studies as a reason not to exercise," says Dr. Sarah Samaan, a cardiologist at Legacy Heart Center and Baylor Heart Hospital Plano as well as an avid horseback rider, cyclist, runner and yoga practitioner. "Exercise absolutely lowers the risk of heart attack, stroke and dementia by 30 percent."
Still, she says, "understand our bodies aren't designed to be put through that stress. If you do marathons, understand there can be risks involved with the heart. If you're going to train, do so in a systematic way."
Dr. Kenneth Cooper, whose running life spanned 44 years and 38,000 miles, says he's much more concerned with obesity and inactivity than "an isolated case of someone running and dying.
"Death doesn't occur that much," says Cooper, who is 81 and now walks regularly. "The chance of dying while exercising is remarkably low. You'll have deaths doing anything — watching football even. The value of exercise is overwhelming compared to the risk, but more isn't always better."
"Honestly, I think most people realize you can do anything to excess," says Dr. Benjamin Levine. He's director of the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian and professor of medicine and cardiology at UT Southwestern Medical Center.
"I don't think most rational people are overly swayed by this," he says. "You can always pick out a piece of information suggesting there may be some risk to very intensive exercise, and I'd be foolish to say there couldn't be any risk. Of course there is. Any exercise tangentially can increase the incidence of having a heart attack compared to doing nothing. But for the most part, people who exercise are healthier."
Heart surgery survivor and marathon runner Don Rossi avidly reads research. He'd never stop running, though; it saved his life, he says.
"I'm so much healthier now that there's no way I'd go back," says Rossi, 51, who no longer takes medicine for hypertension and whose diabetes and weight are well under control.
"Mostly, I don't think twice about the research. I know in the back of my mind I could go out for a run and die, just like I could get in the car and be in a terrible wreck and die. But it's not on my list of things that bother me. If it's my lot in life to die on a run, I can think of worse ways to go."
How much is too much?
Cardiologist and researcher Dr. Chip Lavie offers these takeaways from recent research on running and the heart:
After running a marathon, about 25 percent to 30 percent of people have "significant heart abnormalities," he says. Usually, they reverse "over the next 24 hours and especially over the next seven days," he says.
Runners with the largest mortality benefits are those who run 20 miles a week or less, he says.
"The data isn't so strong that it proves this, but it suggests running more isn't any better than running less but might be worse. It seems you're losing the protection that happens at lower doses."
Intensity is the key word.
"Think if you try to do weights and do a heavy one that's 10 or 15 pounds heavier, what if you lifted it 150, 200 times?" he says. "You'd almost not be able to move the next day. In a way, that's what you're doing in a marathon to the heart muscle. It's one thing if you're doing it for 30, 40 minutes, but another for many hours straight."