Physical Activity: The Real Magic Bullet

JoAnn E. Manson, MD, DrPH


May 23, 2019

This transcript has been edited for clarity.

Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital in Boston, Massachusetts. I'd like to talk with you about physical activity and cardiovascular health, and three recent studies that have helped fill some of the knowledge gaps.[1,2,3]

We all know that physical activity is linked to a reduced risk for heart disease, stroke, type 2 diabetes, osteoporosis, and even cognitive decline. But we've had unanswered questions, such as: Is it ever too late to become physically active? What is the role of light physical activity, especially in older adults who are not engaging in moderate or vigorous physical activity? And third, what is the relationship between physical activity and future risk for heart failure, especially given the very large burden of heart failure in older adults.

These three studies help fill those gaps. Two were published in JAMA Network Open,[1,2] and the third was published in JACC Heart Failure.[3] The first study was from the National Institutes of Health -AARP cohort, and it included 3000 adults, aged 50-71 at enrollment. They were asked about their physical activity over their lifespan. They were asked about activities in adolescence, in their 20s and 30s, and between the ages of 40 and 61.

Of interest, those who became physically active between the ages of 40 and 61, even if not physically active earlier in life, had similar 30%-40% reductions in cardiovascular and all-cause mortality to those who had been physically active over their lifespan, suggesting that it's not too late to start being physically active between the ages of 40 and 61.

The second study,[2] done in the Women's Health Initiative (WHI), was an accelerometer study able to measure light-intensity activities (< 3 metabolic equivalents), such as activities of daily living, chores around the house, gardening, and other activities of that nature. They found that the women, who at the time were in their 70s on average, saw a lower risk for coronary heart disease and total cardiovascular disease (CVD; heart disease plus stroke plus CVD death). If they had done these light activities compared with being sedentary, with each extra hour of light-intensity activity there was a 14% reduced risk for coronary heart disease and an 8% risk for total CVD.

The third study,[3] also from the WHI, looked at walking and moderate physical activity in relation to risk for heart failure. In this study, the women who engaged in regular walking or moderate-intensity exercise had about a 30% lower risk for heart failure. This was true for both preserved and reduced ejection fraction..

These are observational studies and there may be some residual confounding or reverse causation, although there was a very strong effort to adjust for comorbidities, the ability to walk and be active, other types of physical activity, and other lifestyle factors, but the results persisted in the adjusted analyses. Randomized trials are important, and some have documented the importance of physical activity. There is an ongoing randomized trial in the WHI, looking at starting or encouraging higher levels of physical activity in older women and the overall balance of benefits and risks.

But we already have strong and compelling evidence that physical activity is very close to a magic bullet for good health, and it is important to encourage our patients to be physically active; consider writing prescriptions for physical activity. These could be among the most important prescriptions that we write all day. Thank you for your attention. This is JoAnn Manson.

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