Does Racing 42 km Put A Heart At Risk?

In 2005, 382,000 people completed a marathon in the United States , an increase of more than 80,000 since the year of 2000, according to marathonguide.com. Mathematically, the risk is very small: Runner dying from a heart attack during marathon is about 1 in 50,000.

But, does racing 42 km put a heart at risk?

Let's take a look of a new study published in the Nov 28, 2006's issue of Circulation, a journal of the American Heart Association.

60 entrants (41 men, 19 women) from the 2004 and 2005 Boston Marathon were tested before and after the race. Each was given an echocardiogram (ECG) to find abnormalities in heart rhythm and was checked for blood markers of cardiac problems, in particular for troponin, a protein found in cardiac muscle cells.

If the heart is traumatized, troponin can show up in the blood. Its presence can determine whether there has been damage from a heart attack.

The runners had normal cardiac function before the marathon, with no signs of troponin in their blood. 20 minutes after finishing, 60 percent of the group had elevated troponin levels, and 40 percent had levels high enough to indicate the destruction of heart muscle cells.

Most also had noticeable changes in heart rhythms. Those who had run less than 56 km a week leading up to the race, had the highest troponin levels and the most pronounced changes in heart rhythm.

None had reported chest pains or shortness of breath at the finish. All had felt fine.

Within days, the abnormalities disappeared. But something seemed to have happened in the race. Their hearts appeared to have been stunned and the race does have some effect on the cardiac muscles.

Nevertheless, marathons may present an opportunity for silent symptom-less heart disease to surface abruptly. The pulsing excitement, adrenaline and unpleasant process of hitting the wall may trigger physiological changes that loosen arterial plaques, precipitating a heart attack.

The advices given to the runners with any heart trouble is to train for the race, getting the cardiac benefits of endurance exercise, and then watch the event on television.

Anyone considering joining the marathon should undergo a full medical screening, with a visit to a cardiologist for those over 40, and are covered by insurance if recommended by a physician. Those with the family history of cardiac problems should be especially cautious.

Nonetheless, it is still too early to draw any conclusion. According to the researcher, more bodies will be piling up if there were real lingering long-term cardiac damage.

Overall, the evidence is strongly in favor of the idea that endurance exercise is still helpful in terms of cardiac health.