October 19, 2017
Regular walking, even when it's below the minimum recommended levels for physical fitness, is associated with lower all-cause mortality compared with inactivity, according to new data from a large, ongoing US cancer prevention cohort study among older Americans.
"A lot of people find it daunting to start an exercise regimen. They think they have to start jogging or doing something intense," said lead author, Alpa Patel, PhD, a researcher at the American Cancer Society. "There is a tremendous health benefit to simply going out for a walk." Walking is "simple, free and does not require any training" and is "the ideal activity for most Americans, especially as they age," observe Dr Patel and coauthors.
Their new study was published online October 19 in the American Journal of Preventive Medicine. Various US guidelines call for adults to perform either more than 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity physical activity a week to pursue "optimal health." These are recommended minimum amounts.
But the new study showed that 120 minutes or less of weekly moderate-intensity walking is also a boon to one's life span. In other words, you can fall short of the minimum goal for adults and still benefit.
This is not "power-walking," nor is it "strolling through the grocery store," emphasized Dr Patel. The study evaluated walking at "an average pace."
That speed "may cause you to eventually feel a slight increase in your breathing and will allow you to cover roughly a mile in 20 minutes," she said.
"Walking at that pace is a moderate-intensity activity, and that's what a lot of people don't realize," Dr Patel noted.
Any Is Better Than None
Walking is the most common type of physical activity performed by Americans and has been linked to lower risk for heart disease, diabetes, and breast and colon cancers. But the new study is the first to examine walking only (separated out from other activities) in relation to mortality in older men and women.
To do so, Dr Patel and colleagues reviewed data on more than 62,000 men and 77,000 women enrolled in the Cancer Prevention Study II Nutrition Cohort, which surveyed participants repeatedly via mailed questionnaires. The primary endpoint of the current study was death from any cause between 1999 and 2013.
The mean age of the participants in 1999 was 71 years for men and 69 years for women. In the study, 5.8% of men and 6.6% of women reported no moderate to vigorous physical activity at baseline in 1999. These "inactive" individuals were 26% more likely to die prematurely compared with study participants who walked "some" but less than the minimum recommended levels mentioned above (hazard rate ratio, 1.26).
Conversely, higher levels of walking were associated with lower all-cause mortality (hazard rate ratio, 0.80). "You see a 20% lower risk [of mortality]," Dr Patel said about comparing study participants who met or exceeded the minimum recommendation vs those who walked some (but less than the minimum).
The multivariable analyses adjusted for other risk factors, including smoking, obesity, and chronic illnesses. "Clearly, the more you walk the better. But doing any walking is better than doing none. Being completely inactive is the worst," Dr Patel summarized the findings in an interview with Medscape Medical News.
The new study provides "an interesting but perhaps not surprising finding," said Roger Fielding, PhD, professor of nutrition and medicine, Friedman School of Nutrition Science and Policy, Tufts University School of Medicine, Boston, Massachusetts.
"The bottom line is that any physical activity — in this case, less than 2 hours per week of walking — confers substantial and clinically meaningful benefits with respect to mortality," he told Medscape Medical News in an email.
The benefit is enhanced in individuals who meet or exceed the recommended physical activity guidelines, he also summarized, echoing Dr Patel. There is also a dose-response effect of the amount of physical activity, including walking, performed over 2 years with respect to the reduction in mobility and disability risk, Dr Fielding added, citing his own recently published LIFE randomized trial.
Dr Patel also put the new results in absolute numbers, while cautioning that they are not controlled for confounding factors. The age-standardized overall death rate for inactive participants is 4293 per 100,000. And the rate is 2851 for walking less than the recommended amount. That is 1442 fewer deaths per 100,000 than inactive participants.
The rate drops further for those who met and exceeded exercise recommendations: It was only 2088 per 100,000 for walking 1 to 2 times above the recommended levels. "I would consider these to be important risk reductions," concluded Dr Patel.
She also told Medscape Medical News that says she takes daily walks along the 0.2-mile path in the American Cancer Society's Atlanta headquarters' atrium during the workday and in the nearby Centennial Olympic Park.
Her coworkers do likewise. "A lot of people now will do walking meetings instead of sitting in offices," she said.
Regular Walking, Even if Minimal, Tied to Lower Death Risk - Medscape - Oct 19, 2017.