probably not bad for you. Source, Frank Dinenno, a professor in the Department of Health and Exercise Science, and Nate Bachman, a doctoral student in the Human Cardiovascular Physiology Laboratory, studied 25 athletes and 18 "moderately active" Coloradans to determine if excessive aerobic exercise caused damage to the heart. After putting the participants through various fitness tests and medical exams, Dinenno and Bachman came to this conclusion: "...while some ultra-athletes showed some minor calcium buildup in their coronary arteries, they were still healthier overall than a control group of people who only got moderate exercise." Get our free mobile app Despite the fact that eight of the athletes demonstrated calcium buildup, as opposed to two in the control group, researchers found that this had little impact on the participants' risk for coronary heart disease.