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ACC council: Even small amounts of exercise lower CVD risk
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Any amount of exercise, no matter how small, reduces CVD risk, and the more frequent the exercise, the lower the risk, according to a literature review written by the American College of Cardiology’s Sports and Exercise Cardiology Leadership Council.
“The public media has embraced the idea that exercise may harm the heart and disseminated this message, thereby diverting attention away from the benefits of exercise as a potent intervention for the primary and secondary prevention of heart disease,” Michael Scott Emery, MD, from Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, and co-chair of the council, said in a press release. “The available evidence should prompt clinicians to recommend strongly low and moderate exercise training for the majority of our patients. Equally important are initiatives to promote population health at-large through physical activity across the life span, as it modulates behavior from childhood into adult life.”
U.S. guidelines recommend 150 minutes per week of moderate-intensity or 75 minutes per week of vigorous-intensity aerobic exercise in adults for prevention of CVD.
Volume and intensity
Emery and colleagues reviewed published data on what volume and intensity of aerobic exercise is needed for favorable CV health, and whether there is a threshold of exercise that increases CVD risk.
They combined data from population studies from around the world and determined that the exercise volume that conferred the most risk reduction for CV mortality is 41 metabolic equivalent of task hours per week (MET-h/week), equivalent to 547 minutes/week of moderate-intensity exercise at 4.5 METs or 289 minutes/week of vigorous-intensity exercise at 8.5 METs. Compared with those completely inactive, those with exercise volume of 41 MET-h/week had a 45% reduced risk for CVD mortality (HR = 0.55; 95% CI, 0.46-0.66).
They wrote that a number of studies have demonstrated CV and/or mortality benefits of small amounts of physical activity compared with none, including one that found a 10% reduction in all-cause mortality for people who stand more than 2 hours per day (HR = 0.9; 95% CI, 0.85-0.95).
The dose-response curves charting physical activity and CVD mortality are different for moderate exercise and vigorous exercise, Emery and colleagues wrote. For moderate exercise, increasing levels of activity confer more reduced risk for CVD mortality, but for vigorous exercise, the response curve flattens after 11 MET-h/week, they wrote. “This relationship may be due at least in part to the repeated observation that vigorous-intensity exercise acutely, albeit transiently, increases CVD events,” they wrote.
Secondary prevention
For people requiring secondary prevention, there is ample evidence that cardiac rehabilitation reduces risk for CV events and mortality, but there is evidence that high-intensity activities and a high exercise volume per week are no better for risk reduction than inactivity, they wrote.
They concluded that “the possibility that too much exercise training could produce deleterious effects including myocardial fibrosis, coronary calcification and atrial fibrillation is interesting and worthy of scientific investigation; however, overall the results, even for very active, life-long endurance athletes, is that the benefits of exercise training outweigh the risks.” – by Erik Swain
Disclosure: Emery reports no relevant financial disclosures. See the full paper for a list of the relevant financial disclosures of the other authors.
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