It’s news that should reassure anyone running a marathon this spring. A new study led by Assistant Professor Beth Taylor found that prolonged training does not damage the heart. The results of the study, originally published in BMJ Open under the title, “Influence of Chronic Exercise on Carotid Atherosclerosis in Marathon Runners,” have generated a lot of attention, including articles in the New York Times and Runner’s World magazine.
Taylor, an assistant professor in the Department of Health Sciences and Nursing in the University’s College of Education, Nursing and Health Professions, and her team conducted the research in response to some studies that suggested long-time endurance athletes can have a heightened risk for abnormal heartbeats, and experiments with lab animals that found possible links between prolonged, extremely strenuous running and undesirable changes in the structure and function of the heart. It is difficult to isolate the risks associated with strenuous exercise from other lifestyle factors, Taylor told The New York Times. So Taylor and her colleagues decided to better control for such factors by studying marathon runners along with their domestic partners, who presumably would be sharing their lifestyles if not their physical exertions. If cardiac health differed among these couples, the scientists felt, they could reasonably conclude that training had played a role, since so many lifestyle factors would be the same.
With that idea in mind, Taylor and her colleagues surveyed 42 runners who had qualified and signed up for the 2012 Boston Marathon, and their non-running spouses or partners. The participants also had their hearts scanned and cardiovascular disease risk assessed. Half of the runners were women. Their ages ranged from 33 to 59, although most were in their mid- to late 40s. Their partners were around the same age but considerably less active, averaging fewer than two sessions of moderate exercise per week. Many did not formally exercise at all, although most reported frequently walking, gardening or similar moderate-level activities.
The day before the 2012 Marathon, the runners and their partners filled out questionnaires about their exercise and health histories and had their height, weight, pulse rate, blood pressure and other vital signs measured. The participants also gave a blood sample so that researchers could determine the volunteers’ cholesterol and triglyceride profiles. Finally, each volunteer underwent a noninvasive heart scan to reveal the buildup of arterial plaques, an indication of heart disease.
Not surprisingly, the marathon runners were significantly thinner than their partners, although few of the partners were overweight. The runners also generally had lower blood pressure, heart rates, bad cholesterol and other indicators of cardiac health. But running did not insulate the racers altogether from heart disease, the scientists found. Some of the racers, particularly the oldest ones, carried large deposits of plaques in their arteries, a worrying sign.
In essence, the scans showed that marathon training did not cancel out the depredations of age, longstanding bad health habits or a family history of cardiac problems, Taylor said. On the other hand, the scientists found no relationship between the number of hours the runners trained or how fast they ran and the levels of plaque in their arteries, indicating that marathon training had not directly damaged any of these racers’ hearts.
Overall, Taylor said, the data suggests if you’re training for a marathon or otherwise doing frequent and prolonged endurance exercise, you’re probably not hurting your heart and are likely strengthening it. But you should be aware of your past health habits and family history and monitor any symptoms, such as shortness of breath, that could be a sign of potential heart troubles.
Perhaps the more surprising takeaway of the study, Taylor said, is that marathon training’s cardiac benefits may be transferable. “The spouses of the runners were quite healthy, too,” she pointed out. More so than many people, they walked and moved around frequently, and had generally robust cardiac risk profiles.
Taylor maintains a blog, uheart, (http://uheart.wordpress.com/) that documents the progress of her heart- and health-related research interests. It was recently featured by the Hartford Marathon Foundation.
In addition to her scholarship, Taylor serves the community as a member of the Hartford Board of Education. At Hartford Hospital, she is the director of exercise physiology research.