Running: Marathoning dangerous?

Friday, March 30, 2007 - 06:47 PM

After years of coaching marathon runners, Ken Parker had a change of heart that he says may save the hearts of others.

Want to run a marathon? Think again.

Ken Parker, one of the founders of the Ottawa Marathon and former coach of the late Emilie Mondor, one of Canada's greatest distance runners, now finds himself in the unusual position of trying to dissuade people from attempting the event.

Research suggests that the 42-kilometre marathon -- which the fastest men complete in just over two hours, but can take amateurs four hours or longer to finish -- can cause heart disease, irregular heartbeats, damage to the immune system, and post-marathon cardiac dysfunction in under-trained runners.

"It's hard to accept that something that has been championed as a positive addiction could have serious negative consequences," said Parker, who said CBC refused to air his interview on the topic because his comments were too critical. "Maybe it's just that we keep pushing the distances. If more people ran five and 10Ks, perhaps the problem would disappear.

"Most people I know are not even aware of these studies. Of those who are, many blow them off because they are in the business of either coaching or selling."

When it comes to selling -- workout clothes, shoes and training clinics -- nobody does it better than Running Room stores. More than 400,000 North Americans have graduated from their walking and running clinics for races ranging from five kilometres to the marathon.

So if all we need for health is moderate exercise, what's the appeal of the marathon?

"I think the marathon for many people is the horizontal Everest," said John Stanton, the Edmonton-based Running Room founder. "It's the achievement that many people want to achieve. I would disagree with Ken Parker or anyone who says not to recommend the marathon. Do I agree that the training has to be proper? Absolutely. People embarking on training for a marathon should never take it lightly."

The risks of the marathon, it seems, relate to both under- and over-training.

Under-trained amateur marathon runners who run less than 64 kilometres per week often show signs of cardiac dysfunction after the race and some of these abnormalities may persist for up to a month after they cross the finish line. The study of 20 amateur athletes who ran the 2003 Boston Marathon also showed that individuals who consistently ran more than 72 kilometres per week showed no such signs of damage.

On the other hand, putting in higher mileage -- more than 95 kilometres per week -- can also cause problems. Dr. David Nieman at Appalachian State University in Boone, N.C., found that over- training can depress the immune system, doubling athletes' chances of getting sick in the days and weeks following the race. When the immune system is stressed, inflammation results, and there is a link between inflammation and diseases such as heart disease, cancer and arthritis.

This past January a Belgian study published in the European Heart Journal showed how physical wear and tear from years of heavy-duty workouts can predispose an athlete to a rare but potentially deadly condition called ventricular arrhythmia in which the heart beats erratically. Further research is needed to rule out genetics as a factor, said professor Hein Heidbuchel, a cardiologist and the author of the paper.

Just this month, a report in the American Journal of Cardiology described heart disease found in a 51-year-old male that tests showed was induced by too much exercise. So even though aerobic activity has been shown to reduce the risk of heart disease, this case suggests that too much exercise may have the reverse effect in certain people.

"Moderate activity is fine," said Michael Miller, the study's senior author and director of preventive cardiology at the University of Maryland Medical Center. "Extreme activity requires more caution and evaluation."

So where does this leave enthusiastic couch potatoes who still dream of running a marathon? First, both Parker and Stanton agree, get a doctor's approval before starting. Then, start small, very small.

According to Parker, training for a marathon is a "multi-year project" and beginners should to target distances of only five to 10 kilometres.

"When you run, a lot of things happen to your body and most of them are very good, but there's the potential for some things that people should be aware of," Parker said. "It's early days for this information and I don't think that the news is reaching the runners as it should."