title: Objectively Measured Walking Duration and Sedentary Behaviour and Four-Year Mortality in Older People.
abstract: BACKGROUND
  Physical activity is an important component of health. Recommendations based on sensor measurements are sparse in older people. The aim of this study was to analyse the effect of objectively measured walking and sedentary duration on four-year mortality in community-dwelling older people.
  
  
  METHODS
  Between March 2009 and April 2010, physical activity of 1271 participants (≥65 years, 56.4% men) from Southern Germany was measured over one week using a thigh-worn uni-axial accelerometer (activPAL; PAL Technologies, Glasgow, Scotland). Mortality was assessed during a four-year follow-up. Cox-proportional-hazards models were used to estimate the associations between walking (including low to high intensity) and sedentary duration with mortality. Models were adjusted for age and sex, additional epidemiological variables, and selected biomarkers.
  
  
  RESULTS
  An inverse relationship between walking duration and mortality with a minimum risk for the 3rd quartile (102.2 to128.4 minutes walking daily) was found even after multivariate adjustment with HRs for quartiles 2 to 4 compared to quartile 1 of 0.45 (95%-CI: 0.26; 0.76), 0.18 (95%-CI: 0.08; 0.41), 0.39 (95%-CI: 0.19; 0.78), respectively. For sedentary duration an age- and sex-adjusted increased mortality risk was observed for the 4th quartile (daily sedentary duration ≥1137.2 min.) (HR 2.05, 95%-CI: 1.13; 3.73), which diminished, however, after full adjustment (HR 1.63, 95%-CI: 0.88; 3.02). Furthermore, our results suggest effect modification between walking and sedentary duration, such that in people with low walking duration a high sedentary duration was noted as an independent factor for increased mortality.
  
  
  CONCLUSIONS
  In summary, walking duration was clearly associated with four-year overall mortality in community-dwelling older people.
authors.affiliation: Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany.|Department of Geriatrics and Geriatric Rehabilitation, Robert-Bosch-Hospital, Stuttgart, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Klenk
authors.affiliation: Department of Internal Medicine II-Cardiology, University of Ulm Medical Center, Ulm, Germany.|Agaplesion Bethesda Hospital, Geriatric Research Unit, Ulm University and Geriatric Center Ulm/Alb-Donau, Ulm, Germany.
authors.forename: Dhayana
authors.initials: D
authors.lastname: Dallmeier
authors.affiliation: Agaplesion Bethesda Hospital, Geriatric Research Unit, Ulm University and Geriatric Center Ulm/Alb-Donau, Ulm, Germany.
authors.forename: Michael Dieter
authors.initials: MD
authors.lastname: Denkinger
authors.affiliation: Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany.|Department of Geriatrics and Geriatric Rehabilitation, Robert-Bosch-Hospital, Stuttgart, Germany.
authors.forename: Kilian
authors.initials: K
authors.lastname: Rapp
authors.affiliation: Department of Internal Medicine II-Cardiology, University of Ulm Medical Center, Ulm, Germany.|Deutsches Herzzentrum München, Technische Universität München, Munich, Germany.|DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Munich, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Koenig
authors.affiliation: Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany.
authors.forename: Dietrich
authors.initials: D
authors.lastname: Rothenbacher
mesh_terms: D061725:Accelerometry; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D015415:Biomarkers / Q000378:metabolism; D017079:Exercise Tolerance; D005260:Female; D005858:Germany; D006304:Health Status; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality; D009043:Motor Activity; D016016:Proportional Hazards Models; D011446:Prospective Studies; D057185:Sedentary Behavior; D016138:Walking
chemical_list: D015415:Biomarkers