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Physical activity beneficial for CV health, but excessive exercise may confer harm

There is a growing body of literature on the benefits of physical activity and an active lifestyle on CV health, but in the past 10 to 15 years, data have accumulated on CV risks associated with intense and prolonged exercise.

The literature on the CV benefits of exercise is plentiful, but some studies have shown that certain people who exercise at vigorous levels experience a flattening out of CV benefits or an increase in CVD mortality risk. With tragic stories of extreme-endurance athletes experiencing sudden cardiac death during a marathon or exercise training that appear frequently in the media, some experts have posed the question of whether physical activity can be too much of a good thing.

Experts told Cardiology Today that there is some evidence that the risk for sudden cardiac death increases during exercise and for 1 hour afterward, but regular physical activity offers protective CV benefits in the long term. The experts noted, however, that only a small portion of the general population reaches the level of excessive exercise at which long-term CV risks potentially increase, most of the data have been observational and the literature is not definitive.

“Every time somebody goes out and exercises, their risk for a cardiac event is a little higher while exercising, but over the long term, that risk is much lower the other 23 hours of the day than if you weren’t exercising for that hour,” Michael Scott Emery, MD, FACC, cardiologist at Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, said in an interview.

Michael Scott Emery, MD, FACC, from Krannert Institute of Cardiology, University of Indiana, says for most people, regular exercise reduces long-term risk for CV events.
Michael Scott Emery, MD, FACC, from Krannert Institute of Cardiology, University of Indiana, says for most people, regular exercise reduces long-term risk for CV events.

Image credit: Tim Yates, Indiana University School of Medicine; printed with permission.

Overall, exercise is good for heart health and must be a priority, experts told Cardiology Today.

“My advice for sedentary patients is to go for a walk, even just 5 to 10 minutes at a time,” said Michael J. Joyner, MD, professor of anesthesiology at Mayo Clinic in Rochester, Minnesota. “Do something. It doesn’t take much, just 10 to 15 minutes per day, to see a difference.”

There is an ongoing discussion on whether people who exercise and their physicians should be more mindful of the intensity and duration of their workouts to attain maximum CV health benefit, and how health care professionals can encourage sedentary patients to exercise despite the negative headlines they might see.

The exercise paradox

Most current research suggests that moderate exercise reaps the most benefit when it comes to CV health, with extremes on either side associated with potential dangers.

Research published in Heart in 2014 by Ute Mons, MA, PhD, from the German Cancer Research Center, and colleagues demonstrated that physical activity decreased CV mortality in patients who never or rarely exercise. However, in patients who exercised daily, the CV mortality risk was higher than for those who only exercised two to four times per week.

In a study published in Mayo Clinic Proceedings,P.T. Williams, PhD, of the Lawrence Berkeley National Laboratory in Berkeley, California, and Paul Thompson, MD, of Hartford Hospital, Connecticut, focused on the CV benefits of running or walking for survivors of MI. Here again, the dose of exercise determined the CV benefits. The researchers observed that CVD mortality risk, especially related to ischemic heart disease, increased in patients who ran more than 7.1 km per day (4.4 miles per day) or took a brisk walk for at least 10.7 km per day (6.6 miles per day). The risk for ischemic heart disease-related mortalities more than tripled in this group.

Research by Miranda E.G. Armstrong, MPhil(Cantab), PhD, from Oxford University, and colleagues published in Circulation in February 2015 reported similar results. In examining the lifestyle habits of 1 million women from the United Kingdom in the Million Women Study, the researchers found that physical activity up to two or three times per week was associated with a 20% lower risk for CHD, stroke and venous thromboembolism events compared with sedentary women (P < .001 for all). Further, physical activity more than three times per week did not offer further benefits. Compared with participants who exercised two or three times per week, more frequent physical activity increased risk for CHD (P = .002), cerebrovascular disease (P < .001) and VTE events (P < .001).