Light Activity Lowers Cardiovascular Risk in Older Women

Norra MacReady

March 19, 2019

Older women who engage in light physical activity (PA), such as gardening or even folding clothes, may have a significantly lower risk for stroke and other cardiovascular disorders than women who spend less time performing these activities, the authors of a new study report.

In a prospective cohort study of nearly 6000 women aged 63 years or older, light PA was associated with a dose-related reduction in the risk for coronary heart disease (CHD) and cardiovascular disease (CVD), Andrea Z. LaCroix, PhD, MPH, and colleagues explain in an article published online March 15 in JAMA Network Open.

"The highest quartile of light PA was associated with a 42% reduction in the risk of MI [myocardial infarction] or coronary death and a 22% reduced risk of incident CVD events compared with the lowest quartile of light PA," they write.

These benefits persisted after adjustment for variables such as age, functional capacity, and overall health status, LaCroix said in a release about the study. "In other words, the association with light physical activity was apparent regardless of these other factors," she said.

The study is also noteworthy because the authors measured the participants' activity using accelerometers instead of relying solely on self-reports, added LaCroix, who is chair of the Division of Epidemiology and director of the Women's Health Center of Excellence at the University of California, San Diego. "To our knowledge, this is the first study to investigate light physical activity measured by accelerometer in relation to fatal and nonfatal coronary heart disease in older women," she said.

LaCroix noted that in this study, there was no correlation between the women's self-reported light PA and the measurements using the accelerometers, probably because most people do not regard activities such as folding clothes as PA.

These data "support the conclusion that all movement counts for the prevention of CHD and CVD in older women," the authors write.

Association Remains After Adjusting for Other Activity

The findings come from the Objectively Measured Physical Activity and Cardiovascular Health (OPACH) study, an offshoot of the Women's Health Initiative, which was started in the early 1990s to address the lack of information on chronic illness in postmenopausal women.

OPACH enrolled 7058 women aged 63 years or older between March 2012 and April 2014. As part of the study, participants were asked to wear accelerometers 24 hours a day for 7 days. Women who experienced a stroke or myocardial infarction prior to baseline were excluded from the current analysis.

The participants were followed from baseline through February 28, 2017. Medical updates were collected regularly by mail or telephone. Time spent engaged in light PA or moderate to vigorous PA (MVPA) was calculated from the accelerometer data, using activity intensity thresholds previously calibrated by OPACH investigators.

The analysis included data on 5861 women who recorded at least 4 days' worth of accelerometer wear, with 10 or more waking hours per day. The mean age of the participants was 78.5 years (standard deviation [SD], 6.7 years; range, 63 – 99 years). They were followed for a mean of 3.53 years (range, .01 – 4.91 years). Of the cohort, 48.8% were white, 33.5% were black, and 17.6% were Hispanic.

Time spent engaged in light PA ranged from 0.6 to 10.3 hours per day. Women in the lowest quartile spent a mean of less than 3.9 hours per day in light PA; women in the highest quartile spent a daily mean of more than 5.6 hours. Those in the highest quartile had higher levels of physical functioning, fewer comorbidities, and a lower mean body mass index than women in the lowest quartile.

During a follow-up of 20,718 person-years, there were 143 incident cases of CHD and 570 incident cases of CVD. After adjusting for age and race or ethnicity, women in the highest quartile for light PA had a 58% lower risk for CHD compared with those in the lowest (hazard ratio [HR], 0.42; 95% confidence interval [CI], .25 – .70; P for trend, <.001). Similarly, women in the highest quarticle had a 37% lower risk for CVD (HR, .6; 95% CI, .49 – .81; P for trend, <.001).

This association between light PA and lower cardiovascular risk persisted after adjusting for other factors, including educational level, alcohol consumption, comorbidities, and CVD risk factors. The association persisted after accounting for levels of MVPA. "Analyzing light PA as a continuous variable, the risk for incident CHD and CVD events decreased in a linear dose-dependent manner over increasing light PA levels," they write.

The strength of these associations "and their consistency across strata of CVD risk, physical functioning, and MVPA suggest that light PA could have much to offer older women in the prevention of CVD whether or not they can or choose to engage in MVPA," the authors conclude.

These findings support recommendations in the 2018 Physical Activity Guidelines released by the US Office of Disease Prevention and Health Promotion, writes Gregory W. Heath, DHSc, MPH, in an invited commentary about the study.

Current evidence suggests that the level of PA among older women is "clearly insufficient and in need of improvement," writes Heath, Guerry Professor of Exercise Science in the Department of Health and Human Performance, the University of Tennessee at Chattanooga.

"The findings of LaCroix and colleagues should serve as a clarion call to physicians, other health care professionals, health care systems, and public health agencies to embrace, communicate, and promote the 2018 Physical Activity Guidelines to all patients and constituents," he writes.

The study authors and Heath have reported no relevant financial relationships.

JAMA Network Open. Published online March 15, 2019. Full text, Commentary

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