Even Modest Daily Activity May Reduce Mortality Risk for Women

Tara Haelle

November 10, 2016

Even a reasonable amount of light physical activity spread throughout the day is linked to a reduction in women's risk for death from any cause, according to a study published online November 2 in the American Journal of Preventive Medicine. Men had a reduced risk from moderate to vigorous physical activity (MVPA), as recommended daily, but not from light physical activity alone.

These findings come from objectively measured activity levels that are generally more reliable than commonly used self-reporting, which is subject to recall bias and social desirability bias.

"[A]lthough mortality risk differs in those who do little or no MVPA versus those who did only a modest amount, there is little or no difference in risk in those who do a modest amount of MVPA versus those who do a lot," write Emily Borgundvaag, MSc, and Ian Janssen, PhD, from Queen's University in Kingston, Ontario, Canada.

"The dose–response pattern between MVPA and mortality risk is encouraging from a behavior change standpoint," they write. "The message for inactive adults does not need to be to run a marathon, but rather to just do a little bit of MVPA."

The researchers used Actigraph accelerometers to measure the physical activity of 5562 adults, over the course of 4 to 7 days. The adults, who were participants in the 2003 to 2006 National Health and Nutrition Examination Survey and had an average baseline age of 48.4 years, were then tracked for a mean 6.7 years.

The investigators stratified participants into quintiles on the basis of their amount of daily light physical activity (LPA) and their amount of MVPA. They designated the first quintile as low participation, which included 10.0 to 157.0 minutes daily of LPA and up to 3.1 minutes daily of MVPA. Modest to high quintiles of activity ranged from 157.1 to 423.4 minutes per day for LPA and 3.2 to 343.8 minutes daily of MVPA.

After adjusting for age, sex, race, socioeconomic status, diet, smoking, and alcohol consumption, they found that women with modest to high levels of LPA were 42% less likely to die from any cause (hazard ratio [HR], 0.58; 95% confidence interval [CI], 0.38 - 0.88) than those in the low participation group.

In addition, women with moderate to vigorous physical activity in the modest to high quintiles had a 66% lower risk for all-cause mortality (HR, 0.34; 95% CI, 0.20 - 0.57).

The researchers then compared women with different combinations of activity levels with women with only low LPA and low MVPA. They found that adding even a modest amount of MVPA added the greatest benefit: an 84% (HR, 0.16; 95% CI, 0.07 - 0.34) reduction in mortality if they were in the lowest quintile for LPA and 83% reduction if they had modest to high levels of LPA (HR, 0.17; 95% CI, 0.09 - 0.36).

Yet even women with low levels of MVPA had a 58% lower risk for mortality if their LPA levels were modest to high (HR, 0.42; 95% CI, 0.26 - 0.70).

Men, meanwhile, did not have a statistically significant difference in all-cause mortality with LPA (HR, 1.02; 95% CI, 0.64 - 1.61). They did show a 61% (HR, 0.39; 95% CI, 0.27 - 0.56) decreased likelihood of all-cause mortality with MVPA in the modest to high quintiles, but those with low levels of MVPA did not gain any reduction in mortality risk with high levels of LPA.

"In the present study, participants in the second MVPA quintile accumulated 23–69 minutes/week of MVPA, a modest amount of activity by most if not all standards," the authors write. "Eighty-five percent of this MVPA was accumulated sporadically (e.g., a couple of minutes here and there) and not in bouts of MVPA that were at least 10 minutes long."

The research was funded by a Canada Research Chair award. The authors have disclosed no relevant financial relationships.

Am J Prev Med. Published online November 2, 2016. Abstract

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