Authors: Ezra I. Fishman, Jeremy A. Steeves, Vadim Zipunnikov, Annemarie Koster, David Berrigan, Tamara A. Harris, Rachel Murphy
Summary:
Purpose: We examined total, light, and moderate-to-vigorous physical activity (MVPA) as predictors of mortality in a nationally representative sample of older adults. Then, we explored the theoretical consequences of replacing sedentary time with the same duration of light activity or MVPA.
Methods: Using accelerometer measured activity, the associations between total, light (100 to 2019 counts per minute), and moderate-to-vigorous (>2019 counts per minute) activity counts and mortality were examined in adults aged 50 to 79 in the National Health and Nutrition Examination Survey, 2003-2006 (n=3,029), with mortality follow-up through December 2011. Cox proportional hazards models were fitted to estimate mortality risks. An isotemporal substitution model was used to examine the theoretical consequences of replacing sedentary time with light activity or MVPA on mortality.
Results: After adjusting for potential confounders, including age, sex, race/ethnicity, education, body mass index, and the presence of comorbid conditions, those in the highest tertile of total activity counts had one fifth the risk of death of those in the lowest tertile (HR: 0.21, 95% CI: 0.12, 0.38), and those in the middle tertile had one third the risk of death (HR: 0.36, 95% CI: 0.30, 0.44). In addition, replacing thirty minutes of sedentary time with light activity was associated with significant reduction in mortality risk (After 5 years of follow-up: HR = 0.80, 95% CI: 0.75, 0.85). Replacing thirty minutes of sedentary time with MVPA was also associated with reduction in mortality risk (HR = 0.49, 95% CI: 0.25, 0.97).
Conclusions: Greater total activity is associated with lower all-cause mortality risk. Replacing sedentary time with light activity or MVPA may reduce mortality risk for older adults.
Source:
Medicine & Science in Sports & Exercise; 2016.