Daily Activity Energy Expenditure and Mortality Among Older Adults
- Todd M. Manini, PhD;
- James E. Everhart, MD, MPH;
- Kushang V. Patel, PhD, MPH;
- Dale A. Schoeller, PhD;
- Lisa H. Colbert, PhD;
- Marjolein Visser, PhD;
- Frances Tylavsky, PhD;
- Douglas C. Bauer, MD;
- Bret H. Goodpaster, PhD;
- Tamara B. Harris, MD
- Author Affiliations: National Institute on Aging, Laboratory of Epidemiology, Demography and Biometry (Drs Manini, Patel, and Harris) and National Institute of Diabetes and Digestive and Kidney Diseases (Dr Everhart), Bethesda, Md; Departments of Nutritional Sciences (Dr Schoeller) and Kinesiology (Dr Colbert), University of Wisconsin, Madison; Institute of Health Sciences, Faculty of Earth and Life Sciences, VU University and Institute for Research in Extramural Medicine, VU University Medical Center, Amsterdam, the Netherlands (Dr Visser); Department of Biostatistics and Epidemiology, University of Tennessee, Memphis (Dr Tylavsky); Department of Medicine, University of California, San Francisco (Dr Bauer); and Division of Endocrinology and Metabolism, University of Pittsburgh Medical Center, Pittsburgh, Pa (Dr Goodpaster).
- Corresponding Author: Todd M. Manini, PhD, National Institute on Aging, 7201 Wisconsin Ave Gateway Bldg, Suite 3C309, Bethesda, MD 20892 (maninit{at}mail.nih.gov).
Abstract
Context Exercise is associated with mortality benefits but simply expending energy through any activity in an individual's free-living environment may confer survival advantages.
Objective To determine whether free-living activity energy expenditure is associated with all-cause mortality among older adults.
Design, Setting, and Participants Free-living activity energy expenditure was assessed in 302 high-functioning, community-dwelling older adults (aged 70-82 years). Total energy expenditure was assessed over 2 weeks using doubly labeled water. Resting metabolic rate was measured using indirect calorimetry and the thermic effect of meals was estimated at 10% of total energy expenditure. Free-living activity energy expenditure was calculated as: (total energy expenditure × 0.90) − resting metabolic rate. Participants were followed up over a mean of 6.15 years (1998-2006).
Main Outcome Measures Free-living activity energy expenditure (3 tertiles: low, <521 kcal/d; middle, 521-770 kcal/d; high, >770 kcal/d) and all-cause mortality.
Results Fifty-five participants (18.2%) died during follow-up. As a continuous risk factor, an SD increase in free-living activity energy expenditure (287 kcal/d) was associated with a 32% lower risk of mortality after adjusting for age, sex, race, study site, weight, height, percentage of body fat, and sleep duration (hazard ratio, 0.68; 95% confidence interval, 0.48-0.96). Using the same adjustments, individuals in the highest tertile of free-living activity energy expenditure were at a significantly lower mortality risk compared with the lowest tertile (hazard ratio, 0.31; 95% confidence interval, 0.14-0.69). Absolute risk of death was 12.1% in the highest tertile of activity energy expenditure vs 24.7% in the lowest tertile; absolute risks were similar to these for tertiles of physical activity level. The effect of free-living activity energy expenditure changed little after further adjustment for self-rated health, education, prevalent health conditions, and smoking behavior. According to self-reports, individuals expending higher levels of free-living activity energy were more likely to work for pay (P = .004) and climb stairs (P = .01) but self-reported high-intensity exercise, walking for exercise, walking other than for exercise, volunteering, and caregiving did not differ significantly across the activity energy expenditure tertiles.
Conclusions Objectively measured free-living activity energy expenditure was strongly associated with lower risk of mortality in healthy older adults. Simply expending energy through any activity may influence survival in older adults.
