title: Activity energy expenditure and change in body composition in late life.
abstract: BACKGROUND
  Change in body composition, specifically loss of fat-free mass and gain in fat mass, in older adults is a major pathway leading to the onset of functional decline and physical disability.
  
  
  OBJECTIVE
  The objective was to determine the association of activity-related energy expenditure with change in body mass and composition among older men and women.
  
  
  METHODS
  Total energy expenditure (TEE) was assessed over 2 wk by using the doubly labeled water method in 302 community-dwelling older adults aged 70-82 y. Resting metabolic rate (RMR) was measured by using indirect calorimetry, and the thermic effect of meals was estimated at 10% of TEE. Activity energy expenditure (AEE) was calculated as [TEE(0.9) - RMR]. Total body mass, fat-free mass (FFM), and fat mass (FM) were assessed by dual-energy X-ray absorptiometry annually over a mean (+/-SD) of 4.9 +/- 1.3 y.
  
  
  RESULTS
  In multivariate models adjusted for baseline age, smoking status, and race, men and women had a decline (in kg/y) in body mass (men: -0.34, 95% CI: -0.71, 0.02; women: -0.45, 95% CI: -0.71, -0.19) and FFM (men: -0.48, 95% CI: -0.67, -0.29; women: -0.14, 95% CI: -0.026, -0.03). No changes (in kg/y) were observed in FM (men: 0.14, 95% CI: -0.10, 0.38; women: -0.28, 95% CI: -0.49, -0.07). In men and women, higher AEE at baseline was associated with greater FFM. The average change in these outcomes (ie, slope), however, was similar across tertiles of AEE.
  
  
  CONCLUSIONS
  These data suggest that accumulated energy expenditure from all physical activities is associated with greater FFM, but the effect does not alter the trajectory of FFM change in late life.
authors.affiliation: University of Florida, Department of Aging and Geriatric Research, Gainesville, FL 32611-0107, USA. tmanini@aging.ufl.edu
authors.forename: Todd M
authors.initials: TM
authors.lastname: Manini
authors.forename: James E
authors.initials: JE
authors.lastname: Everhart
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Anton
authors.forename: Dale A
authors.initials: DA
authors.lastname: Schoeller
authors.forename: Steve R
authors.initials: SR
authors.lastname: Cummings
authors.forename: Dawn C
authors.initials: DC
authors.lastname: Mackey
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Delmonico
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Bauer
authors.forename: Eleanor M
authors.initials: EM
authors.lastname: Simonsick
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Colbert
authors.forename: Marjolein
authors.initials: M
authors.lastname: Visser
authors.forename: Frances
authors.initials: F
authors.lastname: Tylavsky
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001481:Basal Metabolism / Q000502:physiology*; D001823:Body Composition; D001835:Body Weight; D006233:Persons with Disabilities / Q000706:statistics & numerical data; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D012146:Rest / Q000502:physiology; D012907:Smoking / Q000453:epidemiology