THIS MONDAY, more than 16,000 people will gather in Hopkinton, Massachusetts, pumped up on pasta, prepared to run 26.2 miles. At moments along the course, some will cry. Many will pee, mid-stride, through their shorts. And, according to some new research, a few may come awfully close to death.
Marathon runners have long been touted as poster children for physical fitness. For runners, crossing a marathon finish line is in many ways a rite of passage, a badge of courage, a coming of age. Their sinewy, muscled legs, their relentless drive, their dedicated eyes. Those protein-laden packets of goo they eat, for God’s sake. These folks are tough!
For years now, doctors have been saying that long-distance running batters the body. Runners are familiar with the obvious plagues of knee problems, shin splints, and bad backs, but new research points to the possibility of a far worse fate: death. Late last year, McLean Hospital released two studies indicating a possible connection between marathon running and increased risk of cardiac arrest. In the late 1990s, another researcher at Harvard found that exercise’s best health benefits come from the caloric equivalent of running a total of 20 miles per week — as opposed to 26.2 miles in one day.
It’s a rare marathoner who doesn’t experience an injury while training or during the race. In fact, the litany of distance-runner ills reads like a pharmaceutical drug company’s small print: may lead to stress fractures, lower-back pain, blood in the urine, repetitive-stress injuries, increased risk for eating disorders. But dropping dead — known in clinical terms as sudden cardiac arrest — is another story. Still, word of such serious health woes has yet to put the brakes on those hot to trot. Come Monday, they’ll stretch, they’ll line up — and they just may run their hearts out.
CERTAINLY, there’s such a thing as going too far — and many say a marathon qualifies. "It’s not natural for your body," advises Brian Fitzgerald, an athletic trainer and research-projects coordinator at Boston’s Children’s Hospital, who also sits on the Governor’s Committee on Physical Fitness. "There are road races — but marathons are going a little beyond."
While running has been shown to help prevent heart attacks over time, Arthur Siegel, director of Internal Medicine at McLean Hospital in Belmont, has conducted research showing that some distance runners put themselves at high risk. "There’s a paradox about exercise," he says. "It looks like the more you do, the better off you are. And that’s true, except, unfortunately, during the exercise itself." Siegel compares running to drinking. While a little alcohol may be good for the heart, too much of a good thing can lead to death — the returns diminish after a certain point. And docs are still trying to figure out what the magic number is.
Last October, in the American Journal of Cardiology, Siegel published two concurrent studies linking increased risk of heart-damaging events with long-distance running. Between 1996 and 2001, Siegel drew blood from 80 middle-aged male runners before, immediately following, and a day after the marathon. His findings showed that 24 hours after the race, the men, none of whom had any history of heart disease, exhibited early-stage signs of cardiac damage similar to those that appear during a heart attack.
(The American College of Cardiology recommends that runners over 40 take a stress test before embarking on a marathon. It is usually hidden or asymptomatic conditions that put long-distance runners at risk.)
Siegel explains that running a marathon causes injury to the skeletal muscles, which "sets off a cascade of inflammation in the body." Inflammation, normally a healthy bodily response that initiates muscular repair, also causes blood to thicken and clot. This secondary effect is good in the event of injury because it limits bleeding. But clotting and thickening of the blood can also occur in main arteries, interrupting normal heart function. Prolonged vigorous exercise can raise this normal clotting response to lethal levels, especially in those with a history of heart disease.
In addition, certain cardiac enzymes that show up during heart attacks are also present in some distance runners, a preliminary finding Siegel plans to explore further at Monday’s marathon. While the numbers of mid-marathon deaths are low — around one in 100,000 — Siegel says "sometimes the first symptom they have is a sudden death." But it’s also important to note, says Siegel, that because he tested men with an average age of 47, his findings may not have much bearing on younger heart-healthy runners. And, notes Charles Schulman, a cardiologist and assistant clinical professor at Harvard and the president of the American Running Association, while those enzymes may be elevated, that doesn’t mean the runners will necessarily suffer heart attacks. "These are not specific tests for heart damage," Schulman says. "[The doctors Siegel studied] run the marathon, and they’re perfectly fine. We see them coming back."
Though unusual, marathon casualties do make the news from time to time; most famously, there were two at the 1994 New York City Marathon and another at the Boston Marathon Centennial in 1997. Given their medical knowledge of such events, cardiologists must balance cautioning those at risk with endorsing exercise, which is equally important for good health.
Not surprisingly, Marvin Adner, medical director of the Boston Marathon, leans in favor of running — though he doesn’t deny the risks. "You’re at higher risk for heart attack when you’re running. And when you’re not running, you’re at a lower risk," explains Adner, who adds nonchalantly that he’s had "a few friends" die from running. "In the long run, it’s more value than harm — but some people die doing it."
Another frightening threat to distance runners has emerged in recent years: hyponatremia, a condition that occurs when runners drink too much water. Siegel, who’s in the process of studying the illness, calls it "water-intoxication syndrome." As a result of over-hydrating — which can happen at races in hot climates — the balance of salt and water in runners’ bodies’ gets out of whack, and the concentration of sodium in their blood falls too low, causing an electrolyte disorder. The result? Brain swelling and, in some cases, seizure. Certainly, hyponatremia doesn’t pose as much of a threat in Boston in April as it does in a place like Houston during the summer, when temperatures soar and runners chug water, but doctors will be keeping an eye out for signs of the condition come Monday.
Although, in the end, maintaining adequate electrolyte balance — not just regulating water intake — is most important in preventing conditions such as cardiac arrhythmia.
Marathon running had a portentous start. The 26.2-mile race gets its name from a run taken by an ancient Greek messenger named Phidippides from Marathon to Athens to warn of approaching Persian ships. After finishing the run — which followed days of other lengthy message deliveries — he reportedly dropped dead, after uttering the proclamation, "Rejoice."
Rejoice, indeed. Worldwide, marathons have become a cause for mass celebration, especially in Boston, where a holiday is spent cheering on the throng of sweaty runners. The Boston Marathon, held by the Boston Athletic Association, has been run annually (except 1918) on Patriots’ Day since 1897. In addition to this year’s 16,830 registered participants, organizers anticipate a "fair share of bandits," or unregistered runners, jumping into the course.
Most agree that running can be a tremendous form of exercise. Studies abound pointing to the high-intensity workout's physical boons. In 2000, the American Journal of Hypertension hailed running's effect on lowering blood pressure. The year before that, the American Journal of Public Health reported a link between running and reduced health problems in the obese and overweight. It’s even been reported that regular runners can count on an increased life expectancy of two to seven years. Run an hour, goes the conventional wisdom, add two hours to your life.
Harvard School of Public Health’s Ralph Paffenbarger tracked Harvard alumni over a period of about 40 years. His data showed that exercisers get the most benefit from an energy expenditure equaling approximately 20 miles of running per week, which cuts stroke risk in half and lowers the risk of death from heart disease. But it’s unclear whether adding to that mileage also adds to the benefits; Paffenbarger didn’t test marathoners, and the tests that have been done, like Siegel’s, have not been promising.
