title: Activity energy expenditure and mobility limitation in older adults: differential associations by sex.
abstract: In this study, the authors aimed to determine whether higher activity energy expenditure, assessed by using doubly labeled water, was associated with a reduced decline in mobility limitation among 248 older community-dwelling US adults aged 70-82 years enrolled in 1998-1999. Activity energy expenditure was calculated as total energy expenditure (assessed over 2 weeks by using doubly labeled water) minus resting metabolic rate (measured with indirect calorimetry), with adjustment for the thermic effect of food. Across sex-specific tertiles of activity energy expenditure, men in the lowest activity group experienced twice the rate of mobility limitation as men in the highest activity group (41% (n = 18) vs. 18% (n = 8)). Conversely, women in the lowest and highest activity groups exhibited similarly high rates of mobility limitation (40% (n = 16) vs. 38% (n = 15)). After adjustment for potential confounders, men with higher activity energy expenditure levels continued to show reduced risk of mobility limitation (per standard deviation (284 kcal/day): hazard ratio = 0.61, 95% confidence interval: 0.41, 0.92). Women showed no association (per standard deviation (226 kcal/day): hazard ratio = 1.34, 95% confidence interval: 0.98, 1.85). Greater energy expenditure from any and all physical activity was significantly associated with reduced risk of developing mobility limitation among men, but not among women.
authors.affiliation: Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 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: Kushang V
authors.initials: KV
authors.lastname: Patel
authors.forename: Dale A
authors.initials: DA
authors.lastname: Schoeller
authors.forename: Steve
authors.initials: S
authors.lastname: Cummings
authors.forename: Dawn C
authors.initials: DC
authors.lastname: Mackey
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: D000203:Activities of Daily Living; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002151:Calorimetry; D016001:Confidence Intervals; D004185:Disability Evaluation; D004734:Energy Metabolism; D005260:Female; D005684:Gait / Q000502:physiology; D006304:Health Status; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D051346:Mobility Limitation; D009043:Motor Activity / Q000502:physiology*; D016016:Proportional Hazards Models; D012737:Sex Factors; D011795:Surveys and Questionnaires