Washington: A new study now finds that extreme exercise is not detrimental to the health of athletes.
Sports cardiologist Dr Benjamin Levine led a study, now published in JAMA Cardiology, to find the answer.
Notably, coronary calcium scanning is an imaging test that helps physicians classify patients without cardiac symptoms as low, intermediate, or high risk for heart attack.
It represents how much calcium (and thus cholesterol deposits) has accumulated in the blood vessels that supply the heart. The scan can help physicians determine the need for medication, lifestyle modification, and other risk-reducing measures.
Speaking about the study, Dr Levine said, "The question has never been whether exercise is good for you, but whether extreme exercise is bad for you. For the past decade or so, there's been increasing concern that high-volume, high-intensity exercise could injure the heart. We found that high volumes of exercise are safe, even when coronary calcium levels are high."
High-volume, high-intensity exercise was defined in this study as at least five to six hours per week at a pace of 10 minutes per mile. The average amount of high-intensity exercise in this group was eight hours per week.
Coronary calcium is a footprint of atherosclerosis, a disease in which plaque builds up in the arteries and gives rise to heart attack and stroke.
Dr Levine studied data from the Cooper Center Longitudinal Study. The athletes, a majority of them in middle age, reported their physical activity levels and underwent coronary calcium scanning. Most were predominantly runners, but some were cyclists, swimmers, or rowers. A sub-group of athletes trained in three of these sports.
Despite the findings that extreme exercise does not raise heart disease risk, Dr Levine advised against using the protective effect of exercise to excuse poor lifestyle habits. "You cannot overcome a lifetime of bad behaviours - smoking, high cholesterol, hypertension - just from doing high levels of physical activity, so don't use that as a magical cure," said Dr Levine.
He also recommended caution when starting a new training programme. "If you want to train for a marathon, you have to have a long-range plan to build up slowly before you achieve those volumes and intensity of exercise."
Co-author of the study, Dr Laura DeFina added, "The current study shows no increased risk of mortality in high-volume exercisers who have coronary artery calcium. Certainly, these high-volume exercisers should review their cardiovascular disease risk with their primary care doctor or cardiologists and the study results provide helpful clinical guidance."
"The most important take-home message for the exercising public is that high volumes of exercise are safe. The benefits of exercise far outweigh the minor risk of having a little more coronary calcium," Dr Levine added.