Total Energy Expenditure and Functional Status in Older Adults: A Doubly Labelled Water Study

Objectives Higher total energy expenditure in free living conditions, regardless of any activity, has been strongly associated with a lower risk of mortality in healthy older adults. Also, a good performance in physical and functional tests is a marker of good functional prognosis. However, it is not yet clear what is the association between total energy expenditure and the performance in physical and functional tests. The objective of this study was to verify the association between the total energy expenditure of older adults measured by doubly labelled water and the performance in functional tests. Design Cross-sectional study. Settings and participants Fifty-six older people were recruited from health services linked to the participating institutions. Measurements Socio-demographic, anthropometric and clinical characteristics were assessed through the application of a structured questionnaire. Body composition was evaluated by isotopic dilution of deuterium oxide and functional status was assessed by the gait speed test, 6-minute walk test and handgrip strength. Total energy expenditure (GET) was assessed using the doubly labelled water method and the physical activity profile was verified using an activity monitor based on accelerometery. Results The results showed that the highest total energy expenditure correlated with the best performance in the gait speed tests (r = 0.266; p = 0.047), 6-minute walk test (r = 0.424; p = 0.001) and maximum handgrip strength (r = 0.478; p = 0.000). Multivariate regression analysis in a model adjusted for sex and fat-free mass revealed an association between total energy expenditure and the 6-minute walk test (β = 1.790; t = 2.080; p = 0.044) and the number of sedentary events (β = 6.389; t = 2.147; p = 0.038). Conclusion The results of this study suggest that, in clinical practice, older individuals with lower gait speed, worse performance in the 6-minute walk test and lower handgrip strength, may have lower total energy expenditure, being the stimulus for its increase important for the prevention of possible problems related to low energy expenditure.