Lifestyle+ — 19

The multitude of associated benefits are seen for all major organ systems. As well as reduction in cardiovascular mortality and of cancer mortality, we see a reduction in all-cause mortality. A systematic review of 196 studies with more than thirty million participants reported the link to a 31 percent reduction of all-cause mortality, with a “dose response” of more activity, more benefit. A similar magnitude of benefit was seen for increased physical activity improving sleep in more than four thousand participants studied for ten years.

What does moderate and vigorous physical activity mean? Brisk walking, bicycling on level ground, dancing, or gardening, accompanied by an increase in heart rate and breathing but you can still talk comfortably—that’s moderate. Vigorous activity is breathing hard with a fast heart rate from jogging, swimming laps, competitive sports such as basketball or soccer, elliptical, stair climbing, and other aerobic activities.

Aprospective study of nearly seventy-two thousand adults in the UK Biobank with a wrist-worn accelerometer and followed for about six years confirmed all these favorable outcomes, along with a linear dose-response relationship of increasing benefit with moderate to vigorous physical activity. A beneficial relationship for reduced falls was seen in a large cohort of older women engaged in physical activity of more than 150 minutes per week and for preserving cognitive function in older adults. Overall, women benefit more than men from physical activity with respect to all-cause and heart-related mortality.

However, there is debate as to whether a plateau of benefit exists with moderate or vigorous exercise. On the one hand, a study of more than 400,000 Americans of mean age forty-three years followed for ten years showed no plateau of benefit for mortality reduction. On the other hand, a report on more than 116,000 adults with thirty years of follow-up linked reduction of mortality (all-cause, cardiovascular, noncardiovascular) in people who plateaued their physical activity at 300 to 600 minutes per week for moderate exercise or 150 to 300 minutes per week for vigorous exercise. A systematic review of many studies concurs with this finding, that higher doses are not necessarily associated with greater mortality benefits. Likewise, the large body of evidence from observational studies points away from the alternative hypothesis (fig. 3.5) of any loss of health benefits from too much physical activity.

Despite the wealth of evidence that supports improvement in longevity with exercise, only one in four American adults, by self-report, engage in adequate leisure-time aerobic and muscle strengthening physical activity that meets the guidelines of 150 minutes/week or more of moderate physical activity, or 75 minutes or greater of vigorous physical activity, and muscle strengthening activity at least two times per week. Globally, the proportion of adults with inadequate physical activity has been pegged at 27.5 percent.