In 1924, famous cardiologist Paul Dudley White claimed that "Exercise can't hurt a healthy heart." Over the years, several poorly-controlled studies have shown that ultra-endurance events, such a running a marathon, might impaired heart function. Now a study from Northwestern University shows that Dr. White is still correct (Journal of the American Society of Echocardiography, February 2006). The authors tested 45 patients before they ran the Chicago Marathon and re-tested them one month after the race. They demonstrated that the race had not caused any abnormalities in heart function.

This does not mean that everyone can go out and run a marathon. People who have damaged hearts can die from over-exertion. If you are a middle-aged person who is thinking about starting a vigorous exercise program, you should get a stress test, an electrocardiogram done while you are exercising vigorously. Tests done while a person is at rest often do not pick up blockages in the arteries leading to the heart. If your stress test shows warning signs, you may need further tests. If you pass your stress test, the odds are strong that you can start your exercise program safely. Once you have your doctor's approval, begin your exercise program gradually to build up the strength of your skeletal muscles and your heart over several months. Then you will be ready to start serious training for your marathon or other endurance event.

Gabe Mirkin, M.D.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in Sports Medicine and three other specialties.

Dr. Mirkin's daily features on fitness have been heard on CBS Radio News stations since the 1970's. He has written 16 books including The Sportsmedicine Book, the best-selling book on the subject that has been translated into many languages. His latest book is The Healthy Heart Miracle, published by HarperCollins.

Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. A Boston native, Dr. Mirkin did his residency at the Massachusetts General Hospital. He has served as a Teaching Fellow at Johns Hopkins Medical School, Assistant Professor at the University of Maryland, and Associate Clinical Professor in Pediatrics at the Georgetown University School of Medicine. He has run more than forty marathons and is now a serious tandem bicycle rider with his wife, nutritionist Diana Mirkin.