Physical Activity and All-Cause Mortality in Women
Is accelerometer-measured physical activity and sedentary behavior associated with all-cause mortality?
Data from the Women’s Health Study were used for the present analysis. A total of 18,289 women from the 29,494 living participants agreed to participate in the current study between 2011 and 2015. Women who could not walk unassisted and those with missing physical activity data were excluded. Physical activity (PA) was measured using a triaxial accelerometer, which was worn on the hip for 7 days (except during sleep and water-based activities). The primary outcome of interest was mortality confirmed through medical records, death certificates, or the National Death Index up through December 2015.
A total of 16,741 (96%) women had data from ≥10 h/d on ≥4 days, which was considered compliant for wearing the accelerometer. Mean age for women was 72.0 years (standard deviation, 5.7 years) at baseline, and mean wear time was 14.9 h/d (1.3 h/d). The median times of moderate- to vigorous-intensity PA, light-intensity PA, and sedentary behavior were 28, 351, and 503 min/d, respectively. During an average follow-up of 2.3 years, 207 women died. Total volume of PA was inversely related to mortality after adjustment for potential confounders (p for trend = 0.002). For moderate- to vigorous-intensity PA, a strong inverse association with mortality was observed (p for trend = 0.0002). This association persisted in sensitivity analyses that excluded women with cardiovascular disease and cancer and those rating their health as fair/poor or deaths in the first year. For light-intensity PA, a significant inverse association was observed (p for trend = 0.04). However, with adjustment for potential confounders and moderate- to vigorous-intensity PA, this association was no longer observed. Sedentary behavior was associated with an increased risk for mortality (p for trend = 0.007), which was nonsignificant after further adjustment for potential confounders and moderate- to vigorous-intensity PA.
The authors concluded that PA volume is inversely associated with all-cause mortality, with the strength of this relationship due to volume of moderate to vigorous PA, rather than light PA or amount of sedentary time.
Reduced mortality risk has been observed for moderate to vigorous PA in prior studies. However, as the authors point out, most studies to date have used self-reported PA, rather than objectively measured. It is interesting that light activity and sedentary behaviors were not associated with mortality. These findings need to be confirmed and measured in diverse cohorts, which include variation in race/ethnicity, gender, and socioeconomic factors.
Keywords: Accelerometry, Cardiovascular Diseases, Exercise, Motor Activity, Neoplasms, Primary Prevention, Sedentary Lifestyle, Self Report, Socioeconomic Factors, Walking, Women
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