Is long distance running too much of a good thing?

10/16/2013

Come Sunday, Oct. 20, more than 20,000 people will participate in the Detroit Free Press Marathon. Given the popularity of the sport and the well-publicized deaths of athletes at running events, Beaumont researchers did a study to assess heart risks in marathon runners. They wanted to know: Is running 26.2 miles too much of a good thing?

Marathon running has increased in popularity over the past four decades with participation in the United States rising from 25,000 runners in the mid-1970s to more than 500,000 today. At the same time, it is estimated that six to eight marathon runners nationwide will die each year due to heart problems and physical and/or environmental stresses.

During the 2009 Detroit Free Press Marathon and Half-Marathon, three runners collapsed and died of heart-related problems. Two of the runners were participating in the half-marathon.

To look at the risks of marathon running, Beaumont cardiologist Justin Trivax, M.D., and his research team recruited 25 registrants of the 2008 Detroit Free Press Marathon as volunteer research subjects. After verifying age; the absence of signs, symptoms, or medical history of heart disease, 13 women and 12 men were randomly chosen to participate from 428 registrants who showed interest in the study.

Each runner was monitored with blood tests and imaging during training, one to four weeks before the marathon and immediately after they crossed the finish line. All underwent electrocardiography monitoring and cardiac magnetic resonance imaging. A repeat cardiac MRI was performed six months following the marathon.

Study results were published in the Journal of Applied Physiology, "Acute cardiac effects of marathon running," and as an abstract in the American Heart Association's Circulation.

While the research determined there is evidence that marathon running causes right-heart overload, it does not appear to result in permanent injury to any chamber. Explains Dr. Trivax, "Due to exertion from prolonged exercise, the right atrium and ventricle become enlarged or dilated. All of the acute changes seen immediately after the marathon normalized six months later."

Dr. Trivax and a multidisciplinary team plan on opening a new Cardiovascular Performance Clinic for athletes who engage in high-volume, high-intensity exercise. The Beaumont Health Center-based clinic will offer amateur and professional athletes state-of-the-art diagnostic and physiologic testing. The medical team will include sports medicine/exercise physiologists; physicians specializing in adult and pediatric cardiology, internal medicine, pulmonary medicine and endocrinology; dietitians; rehabilitative therapists and athletic trainers. Each athlete will receive counseling and specific training recommendations. By providing these services, the new clinic aims to assist the growing number of recreational athletes seeking to improve their performance, while maximizing the benefits and reducing the associated risks of high-intensity exercise.

"Exercise both protects and provokes cardiovascular events," adds Dr. Trivax, a runner himself. "It's important to remember, the overall benefits of exercise far outweigh the risks.

Most physicians and researchers agree sudden death during exercise, like running long distances, is almost always heart-related. Deaths of runners under 30 years of age usually are due to structural abnormalities of the heart, like hypertrophic cardiomyopathy, causing a thickening of the heart muscle. Runners over 30 usually die due to plaque rupturing in their coronary artery.

"The bottom line is anyone interested in long distance running, no matter their age, should be carefully evaluated by a cardiologist before beginning an exercise program," says Dr. Trivax. "The doctor will ask about your family health history for underlying congenital and acquired forms of heart disease. Any history of fainting or cardiac arrest during or shortly after a run deserves a full evaluation for structural and coronary heart disease. Our study also showed that if a runner experiences palpitations it may signal the occurrence of atrial fibrillation."

Dr. Trivax says runners should be carefully evaluated
by a cardiologist before beginning any exercise program.