CardioBrief: Benefits Of Physical Activity Seen Worldwide
Observational studies have consistently established a link connecting physical activity and cardiovascular health, but the vast majority of this research has occurred in high-income countries, where physical activity is often recreational. Now the latest report from an enormous worldwide observational study offers powerful evidence that the connection exists in less developed countries as well, where physical activity is mostly non-recreational.
After 6.9 years of follow-up in the PURE study, Scott Lear (Simon Fraser University) and colleagues concluded that "physical activity is associated with reduced risk of mortality and incident cardiovascular disease in all regions of the world. The greatest reductions occurred at the lowest and continued to be present at very high levels of physical activity with no indication of a ceiling effect." The findings were published in The Lancet and were based on questionnaires administered to more than 130,000 people in 17 countries.
The current report will almost certainly be less controversial than the previous major publication from the PURE study, which failed to provide evidence for a broad swath of conventional nutritional wisdom concerning dietary fats and carbohydrates. By contrast, the new PURE paper supports and amplifies the popular view that physical activity is beneficial.
Lear and colleagues calculated that 8% of deaths and 4.6% of CV disease cases were attributable to people not meeting physical activity guidelines. They further calculated that the benefits would be even greater if more people would reach even higher levels of physical activity.
Physical activity showed positive effects throughout a broad range of exercise time, from 150 minutes per week of recreational activity and 750 minutes per week of overall moderate intensity out to 1,250 minutes per week of non-recreational activity.
Benefits were observed with physical activity as little as 30 minutes a day five times a week. "The largest risk reductions are seen between participants not meeting current physical activity recommendations and those meeting these recommendations -- the equivalent of 150 min of moderate activity per week, from all forms of physical activity," the authors reported.
Lear and colleagues found no evidence of reduced benefits at the highest level of physical activity. "We did not observe any adverse effects of physical activity on our outcomes even in the approximately 9,000 participants who reported over 2,500 minutes per week of moderate intensity physical activity (equivalent to 17 times that of the physical activity guidelines)."
The authors strongly supported greater efforts to increase physical activity at a public health level. "Increasing physical activity is a simple, widely applicable, low cost global strategy that could reduce deaths and CVD in middle age," they concluded.
The authors sought "to address concerns related to reverse causality" by excluding people with known CV disease and by performing subgroup analyses in groups based on risk factors.
In an accompanying comment, Shifalika Goenka ((New Delhi, India) and I-Min Lee (Brigham and Women's Hospital) write that the "study indicates that all types of physical activity are equally effective, and the protection accrued from physical activity in the current study that includes low-income countries and middle- income countries seems to be of similar magnitude."
They also supported efforts to encourage physical activity. "Creating a physical, social, and political environment where physical activity in daily living is desirable, accessible, and safe should be a developmental imperative; a planning, economic, social, and equity imperative; and a public health imperative. Parallel to pedestrian pavements, we need additional active transport roads for the many different modes of active transport along with cycling."
Physical Activity and Secondary Prevention
The PURE paper focused exclusively on the role of physical activity in primary prevention. A separate and unrelated paper published in the Journal of the American College of Cardiology offers important evidence that physical activity is equally beneficial for secondary prevention in people with stable coronary heart disease. Ralph Stewart and colleagues report on the 15,486 patients who participated in the lifestyle substudy of the previously published STABILITY trial.
"At a population level, the greatest benefits to health are likely to be achieved by modest increases in exercise in sedentary persons, especially in persons who have a higher risk of adverse events, and those with exertional angina and dyspnea," the authors concluded.
The results in STABILITY were similar to the PURE results. There was a clear association between increasing levels of physical activity and reductions in both all-cause and cardiovascular mortality. The greatest reductions in mortality were observed in the "modest increases in physical activity" compared with sedentary persons. Increased activity continued to be beneficial but the incremental benefit declined.
Valentin Fuster, of the Icahn School of Medicine at Mt. Sinai, the editor-in-chief of JACC, said that the PURE and STABILITY results were completely consistent, offering reassurance that physical activity, even at high levels, is extremely effective for both primary and secondary prevention.
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