Predicting energy expenditure in elders with the metabolic cost of activities

Introduction: Measuring free-living energy expenditure in aging human is a considerable challenge. The objective of this study was to predict total energy expenditure (TEE) in elders by combining the metabolic cost of activities and accelerometer outputs. Methods: Seventeen elders (7 women, 10 men) aged 60 to 78 yr were recruited. Body composition was measured by dual x-ray absorptiometry. Doubly labeled water was used as the criterion standard to measure TEE on a 7-d time frame. During the same period, participants wore a uniaxial accelerometer (Caltrac) to estimate TEE. Resting metabolic rate and metabolic costs of sitting, standing, and walking (1, 3, and 5 km[middle dot]h-1) were measured by indirect calorimetry. Results: There was no correlation between Caltrac's outputs and doubly labeled water measurement of TEE. The best predictors of TEE were fat-free mass, the metabolic cost of standing, and the metabolic cost of walking at 3 km[middle dot]h-1 (r2 = 0.78, P < 0.01). Conclusions: Our results suggest that TEE may be estimated with good accuracy using fat-free mass, the cost of standing still, and the cost of walking at 3 km[middle dot]h-1. These predictors are easy to measure in older adults. Further work is needed to confirm our findings and develop prediction equation with these parameters