title: Accelerometer-measured dose-response for physical activity, sedentary time, and mortality in US adults.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Division of Cancer Epidemiology and Genetics, Nutritional Epidemiology Branch, charles.matthews2@nih.gov.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Matthews
authors.affiliation: Division of Cancer Epidemiology and Genetics, Nutritional Epidemiology Branch.
authors.forename: Sarah Kozey
authors.initials: SK
authors.lastname: Keadle
authors.affiliation: Epidemiology and Genomics Research Program, and.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Troiano
authors.affiliation: Information Management Services Inc., Silver Spring, MD.
authors.forename: Lisa
authors.initials: L
authors.lastname: Kahle
authors.affiliation: Care and Public Health Research Institute School for Public Health and Primary Care, Department of Social Medicine, Maastricht University, Maastricht, Netherlands.
authors.forename: Annemarie
authors.initials: A
authors.lastname: Koster
authors.affiliation: National Institute of Diabetes and Digestive and Kidney Diseases, Diabetes, Endocrinology, and Obesity Branch, Bethesda, MD.
authors.forename: Robert
authors.initials: R
authors.lastname: Brychta
authors.affiliation: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors.forename: Dane
authors.initials: D
authors.lastname: Van Domelen
authors.affiliation: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors.forename: Paolo
authors.initials: P
authors.lastname: Caserotti
authors.affiliation: National Institute of Diabetes and Digestive and Kidney Diseases, Diabetes, Endocrinology, and Obesity Branch, Bethesda, MD.
authors.forename: Kong Y
authors.initials: KY
authors.lastname: Chen
authors.affiliation: National Institute on Aging, Intramural Research Program, Laboratory of Epidemiology, Demography, and Biometry, Bethesda, MD.
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
authors.affiliation: Behavioral Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD.
authors.forename: David
authors.initials: D
authors.lastname: Berrigan
mesh_terms: D061725:Accelerometry / Q000379:methods*; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D057185:Sedentary Behavior; D012959:Socioeconomic Factors; D014481:United States
keywords: accelerometer; light-intensity activity; moderate-to-vigorous intensity activity; mortality; physical activity; sedentary behavior