Research Study Abstract

Accelerometer-measured dose-response for physical activity, sedentary time, and mortality in US adults

  • Published on Oct 5, 2016

Background: Moderate-to-vigorous–intensity physical activity is recommended to maintain and improve health, but the mortality benefits of light activity and risk for sedentary time remain uncertain.

Objectives: Using accelerometer-based measures, we 1) described the mortality dose-response for sedentary time and light- and moderate-to-vigorous–intensity activity using restricted cubic splines, and 2) estimated the mortality benefits associated with replacing sedentary time with physical activity, accounting for total activity.

Design: US adults (n = 4840) from NHANES (2003–2006) wore an accelerometer for ≤7 d and were followed prospectively for mortality. Proportional hazards models were used to estimate adjusted HRs and 95% CIs for mortality associations with time spent sedentary and in light- and moderate-to-vigorous–intensity physical activity. Splines were used to graphically present behavior-mortality relation. Isotemporal models estimated replacement associations for sedentary time, and separate models were fit for low- (<5.8 h total activity/d) and high-active participants to account for nonlinear associations.

Results: Over a mean of 6.6 y, 700 deaths occurred. Compared with less-sedentary adults (6 sedentary h/d), those who spent 10 sedentary h/d had 29% greater risk (HR: 1.29; 95% CI: 1.1, 1.5). Compared with those who did less light activity (3 h/d), those who did 5 h of light activity/d had 23% lower risk (HR: 0.77; 95% CI: 0.6, 1.0). There was no association with mortality for sedentary time or light or moderate-to-vigorous activity in highly active adults. In less-active adults, replacing 1 h of sedentary time with either light- or moderate-to-vigorous–intensity activity was associated with 18% and 42% lower mortality, respectively.

Conclusions: Health promotion efforts for physical activity have mostly focused on moderate-to-vigorous activity. However, our findings derived from accelerometer-based measurements suggest that increasing light-intensity activity and reducing sedentary time are also important, particularly for inactive adults.


  • Charles E Matthews 1
  • Sarah Kozey Keadle 1
  • Richard P Troiano 2
  • Lisa Kahle 4
  • Annemarie Koster 6
  • Robert Brychta 5
  • Dane Van Domelen 7
  • Paolo Caserotti 7
  • Kong Y Chen 5
  • Tamara B Harris 8
  • David Berrigan 3


  • 1

    Division of Cancer Epidemiology and Genetics, Nutritional Epidemiology Branch

  • 2

    Epidemiology and Genomics Research Program

  • 3

    Behavioral Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD

  • 4

    Information Management Services Inc., Silver Spring, MD

  • 5

    National Institute of Diabetes and Digestive and Kidney Diseases, Diabetes, Endocrinology, and Obesity Branch, Bethesda, MD

  • 6

    Care and Public Health Research Institute School for Public Health and Primary Care, Department of Social Medicine, Maastricht University, Maastricht, Netherlands

  • 7

    Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark

  • 8

    National Institute on Aging, Intramural Research Program, Laboratory of Epidemiology, Demography, and Biometry, Bethesda, MD


The American Journal of Clinical Nutrition


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