October 27, 2010

Marathons Can Damage The Hearts Of Less-Fit Runners

(Ivanhoe Newswire) -- We run to the store. We run to the bank. We run everywhere daily, but how about a marathon? Is running a marathon good for you or can it damage your heart?

A team of researchers and runners from the Heart and Stroke Foundation are trying to answer the question of whether or not fitness level matters. They used a traditional test that uses data from an MRI to find out what is really going on in the marathoner's heart as the kilometers go up. They found that that the magnitude of abnormal heart segments was more widespread and significant in a group of less fit runners. During the marathon, they had signs the heart might be at greater risk of damage than that of runners who had better training or at least had better exercise capacity.

"Without proper training, marathon running can damage your heart. Fortunately the exercise-induced injury is reversible over time," Dr. Eric Larose, professor of medicine at Laval University and a cardiologist and clinical researcher at Institut universitaire de cardiologie et de pneumologie de Qu©bec (IUCPQ) in Qu©bec City was quoted saying.. "But it could take up to three months to completely recover."

The left ventricle of the heart is divided into 17 segments that make up the heart as a whole. When a segment is injured or stressed out during the marathon, its neighbors on either side can take over to perform the function of the damaged area. This makes the heart as a whole appear stronger and fitter than is really the case when considering each individual segment. That makes it impossible for physicians to arrive at an accurate assessment of the heart health when considering the whole heart.

Researchers turned to the VO2 max test. This ultimate measure of aerobic endurance directly measures body oxygen consumption and it is the best test to provide an accurate measure of a safe maximum heart rate (number of beats per minute) for runners. In V02 testing, treadmills or stationary bicycles may be used to establish cardiac fitness.

In this test, researchers took healthy amateur runners and performed a full evaluation six to eight weeks before, and then immediately after, they ran a marathon. They underwent exercise tests, blood analysis, and magnetic resonance imaging.

"What we did notice in this study is a runner with less preparation before the marathon had lower V02 max, so they had lower exercise capacity. "   Dr. Larose was quoted saying. "Compared to those runners with better training, they became more dehydrated and their hearts showed greater signs of injury. The less well trained runners also experienced greater loss of function associated with lower blood flow and greater irritation of heart segments."

They advise new runners to train properly; stay hydrated and most importantly, speak to their doctors about what is right for them.

SOURCE: Canadian Cardiovascular Congress, October 2010