LaMonte MJ, et al. - Researchers prospectively examined older women to gauge the links between accelerometer-measured physical activity (PA) and mortality, focusing on light-intensity PA. They found that older women exhibited a link between light-intensity and moderate-to-vigorous PA (MVPA) with lower mortality, when accelerometers were used to measure PA. Data suggested that an aging society could benefit from replacing sedentary time with light-intensity PA.

Methods

• Researchers used a prospective cohort study design with baseline data collection between March 2012 and April 2014.
• This study was performed in the setting of Women's Health Initiative cohort in the US.
• Participants were community-dwelling women aged 63 to 99 (N=6,382).
• Measurements included minutes per day of usual PA measured using hip-worn triaxial accelerometers, physical functioning measured using the Short Physical Performance Battery, mortality follow-up for a mean 3.1 years through September 2016 (450 deaths).

Results

• They found that relative risks (95% confidence intervals) for all-cause mortality across PA tertiles were 1.00 (referent), 0.86 (0.69, 1.08), 0.80 (0.62, 1.03) trend P=.07, for low light; 1.00, 0.57 (0.45, 0.71), 0.47 (0.35, 0.61) trend P < .001, for high light; and, 1.00, 0.63 (0.50, 0.79), 0.42 (0.30, 0.57) trend P < .001, for moderate-to-vigorous PA (MVPA), when adjusted for accelerometer wear time, age, race-ethnicity, education, smoking, alcohol, self-rated health, and comorbidities.
• They observed that after further adjustment for physical function, links continued to be significant for high light-intensity PA and MVPA (P < .001).
• Findings demonstrated the association of each 30 minutes/day increment in light-intensity (low and high combined) PA and MVPA, on average, with multivariable relative risk reductions of 12% and 39%, respectively (P < .01).
• They observed that the inverse links remained significant after further simultaneous adjusting for light intensity and MVPA (light-intensity PA: RR = 0.93, 95% CI = 0.89–0.97; MVPA: RR = 0.67, 95% CI = 0.58–0.78).
• No difference was found in these relative risks between subgroups for age or race and ethnicity (interaction, P ≥ .14, all).