EXERCISE

Purpose . Research demonstrates that moderate-to-vigorous physical activity (MVPA) is associated with a reduced risk of all-cause mortality. Few studies have examined the effects of light-intensity physical activity on mortality. Therefore, the purpose of this study was to examine the association between objectively measured light-intensity physical activity and all-cause mortality risk.

Design . Longitudinal. Setting . National Health and Nutrition Examination Survey 2003-2006 with follow-up through December 31, 2011.

Subjects . Five thousand five hundred seventy-five U.S. adults.

Measures . Participants wore an accelerometer for at least 4 days and completed questionnaires to assess sociodemographics and chronic disease information, with blood samples taken to assess biological markers. Follow-up mortality status was assessed via death certificate data from the National Death Index.

Analysis . Cox proportional hazard model.

Results . After adjusting for accelerometer-determined MVPA, age, gender, race-ethnicity, cotinine, weight status, poverty level, C-reactive protein, and comorbid illness, for every 60-minute increase in accelerometer-determined light-intensity physical activity, participants had a 16% reduced hazard of all-cause mortality (hazard ratio = .84; 95% confidence interval: .78-.91; p<.001).

Conclusion . In this national sample of U.S. adults, light-intensity physical activity was inversely associated with all-cause mortality risk, independent of age, MVPA, and other potential confounders. In addition to MVPA, promotion of light-intensity physical activity is warranted.