Extreme exercise is riskyThursday, June 14, 2012 12:00 AM Views : 330Journal Online
EXERCISE, they say, can give lots of health benefits, but too much can be bad for the heart.
Recent evidence suggests training for and participating in extreme endurance exercises, such as marathons and triathlons, may cause heart problems in some.
A web post quoted Dr. James O'Keefe, a cardiologist at Saint Luke's Hospital in Kansas City, as saying that there's very little to gain from doing more than about an hour of exercise a day.
However, experts emphasize that exercise is very important for health, and the proportion of endurance athletes at risk for exercise-related heart problems is quite small: The rate of sudden cardiac death among marathon participants is one in 100,000.
One should undergo an examination from a heart doctor before participating in any strenuous exercise or activities. While tests cannot predict for sure whether an athlete will experience heart problems down the road, they can provide clues to how big a person's risk may be.
Studies suggest extreme endurance training can cause temporary changes to the heart's structure, such as stretching of tissue, and increases in certain biomarkers known to be associated with heart injury. These factors have been shown to return to normal after one week, but over time, repeated bouts of extreme exercise may lead to more permanent damage, such as heart scaring, in some people.
In one study of about 100 apparently healthy marathon runners, 12 percent showed evidence of heart scaring, a rate three times higher than that of non-marathon runners. Heart scaring can increase the susceptibility to heart rhythm problems.
Extreme exercise has also been associated with an increased risk of calcium build up in artery walls, leading to a narrowing of the arteries.
To exercise for health, take 150 minutes of moderate exercise per week, or 75 minutes of vigorous exercise per week.
People who ran moderate distances at moderate speeds, and exercised a few times a week lived longer than those that ran longer distances at faster speeds.