Marathoning may be run for your life

`Double-edged': The 26-mile race can be beneficial, but also can lead to heatstroke, water intoxication and heart failure.

April 07, 2003|By Stephen Smith | Stephen Smith,NEW YORK TIMES NEWS SERVICE

It is hailed as the zenith of human performance, an event testing the mettle of athletes - the marathon, a 26-mile, joint-jolting measure of running prowess and emotional endurance. But just how good is it for the human body to be pushed so far for so long?

"I don't think anybody can tell you what the optimal level of physical activity is to get all of the health benefits that we all want," said Dr. Miriam Nelson, a nutrition and physical activity specialist at Tufts University's Friedman School. "But the reality is, it's not the marathon."

But for those who will take feet to pavement for the Boston Marathon on April 21 and other long races, it's caveat runner. There are the minor injuries - pulled muscles, blisters, shin splints. And then there are the potentially life-threatening medical crises - heatstroke, water intoxication, heart failure.

"It is a double-edged sword," said 1976 Boston Marathon champion Jack Fultz, now coach of the Dana-Farber Marathon Challenge team and an adviser to Nike. "Training for and running a marathon can be a very beneficial thing for one's physical stature, but it can also be very detrimental."

To be sure, most runners finish the race without major complications. But, as the death last year of Boston Marathon runner Cynthia Lucero revealed, marathoning is no trivial pursuit.

Lucero's demise was attributed to drinking excessive fluids, a phenomenon known as hyponatremia - water intoxication. For runners accustomed to the maxim that too much water is never enough, Lucero's death demonstrated the perils of extreme amounts of liquid - a profound dilution of sodium in the blood, which can cause lethal brain swelling.

More broadly, researchers have come to understand that the water intoxication of marathoners reflects the body's systemic response to being driven to such extremes. In fact, Dr. David Greenes of Children's Hospital Boston, who is presiding over a major study of runners' health, refers to a marathon as "a scheduled disease."

Last year, his research team tracked 484 Boston Marathon runners. The findings await release, but Greenes revealed that a substantial number had dangerously low sodium levels - even if they had not complained of related symptoms.

"There are, no doubt, some health benefits to training as vigorously as people do for marathoning," he said. "But I think there are also ... some risks. We as a medical community need to understand what the risk factors are for the rare but unfortunate outcomes that we see."

That is precisely what Dr. Arthur Siegel has been doing after hanging up his marathon shoes in the late 1980s. His work revolves around the notion that marathoning produces such acute injury to the body that a massive inflammatory response ensues.

A manifestation of that, he said, can be found in the blood. After examining samples from 80 marathoners, Siegel concluded that the morning after a race, the balance between blood thickening and thinning factors was out of whack. Clotting and inflammatory factors were elevated, putting runners at risk of heart attacks.

Kidneys can be inflamed, too, Siegel reported, further evidence of what happens when asking the body to cover 26 miles in a few hours. A marathon "is an overdose of a good thing," said Siegel, of McLean Hospital in Belmont, Mass. "But the point is not to scare people out of doing it. The point is helping them do it more safely."

That's why Siegel recommends that marathoners consider taking an aspirin to give them an edge against potential blood clotting.

"What I tell people is that a marathon is a very special event," added Dr. Lyle Micheli, who has treated marathon injuries for three decades. "Don't think of it as part of your daily health regimen."

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