Darlene Backlund, 73, of Palm Springs completes a 50K race walk in Santee. But older women don’t have to walk that far to gain benefits. Photo by Ken Stone

UC San Diego researchers said Tuesday that light-intensity physical activity, including shopping or a casual walk, can protect mobility in older women.

According to the study from the school’s Herbert Wertheim School of Public Health and Human Longevity Sciences, one in four women over age 65 is unable to walk two blocks or climb a flight of stairs. Known as mobility disability, it is the leading type of incapacity in the United States and a key contributor to a person’s loss of independence.

In Tuesday’s online issue of JAMA Open, researchers found that women who did not have a mobility disability at the start of the study, and who spent the most amount of time doing light-intensity activities, were 40% less likely to experience loss of mobility over a six-year period.

“Older adults who want to maintain their mobility should know that all movement, not just moderate-to-vigorous physical activity, counts,” said senior author Andrea LaCroix, professor and chief of the Division of Epidemiology at Herbert Wertheim School of Public Health. “We found that, among older women, light-intensity physical activity preserves mobility later in life.”

Researchers observed 5,735 women age 63 and older living in the United States and enrolled in a study by the Women’s Health Initiative. Participants wore a research-grade accelerometer for seven days to obtain accurate measures of their physical activity. The mean time spent in light physical activity was 4.8 hours per day.

Researchers found that women who spent the most time performing light- intensity physical activity had a 46% lower risk of mobility loss compared to women who participated in lower levels of physical activity. Similar results were observed among white, Black and Latina women. Women with and without obesity also reduced their risk of mobility disability, but the benefit was strongest among women with a body mass index of less than 30.

“Moderate-to-vigorous physical activity is increasingly more difficult to perform as people age,” said co-author John Bellettiere, professor of epidemiology. “Considering the aging population in the United States, these findings could have major impacts on public health recommendations, putting more focus on the importance of light physical activity to improve the health and well-being of older women. Doing so may help women maintain mobility and independence as they age.”

Authors said their data suggest light activity is likely important for maintaining mobility, which is essential for healthy aging.

“The highest levels of light-intensity physical activity are unnecessary,” said first author Nicole Glass, a doctoral candidate in the San Diego State University/UCSD Joint Doctoral Program in Public Health. “After five hours of activity, we observed no further increase in benefit.

“In addition, our results showed that light-intensity physical activity was associated with preserved mobility regardless of the amount of higher-intensity physical activities, such as brisk walking, jogging or running, the women engaged in. So whether you exercise or not, higher light-intensity physical activity is healthy,” Glass continued.

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