Activity-related energy expenditure (AEE) correlates with physical activity volume; however, between-person differences in body size and walking economy (net V̇o2) can influence AEE. The ratio of total energy expenditure (TEE) and resting energy expenditure (REE) estimates physical activity level (PAL) relative to body mass, yet does not account for variance in walking economy. The activity-related time equivalent (ARTEwalk) circumvents such constraints by adjusting for individual-specific walking economy. Herein, we compared AEE, PAL, and ARTEwalk index in a cohort (n = 81) of postmenopausal women while examining possible associations with biomarkers of cardiometabolic health. Secondary analyses were performed on postmenopausal women dichotomized above/below age group 50th percentile for body fat percent. TEE was reduced by 10% for the thermogenesis of digestion wherein AEE was calculated by subtracting REE from adjusted TEE. PAL was calculated as the ratio of TEE/REE. AEE was divided by the mean net energy expenditure of nongraded walking to calculate the ARTEwalk index. Between-group differences were not detected for AEE or PAL. However, the ARTEwalk index revealed that participants with less adiposity were more physically active (258 ± 149 vs. 198 ± 115 min·day-1; P = 0.046; g = 0.46). AEE and PAL did not correlate with cardiorespiratory fitness or biomarkers of cardiometabolic health. Cardiorespiratory fitness (r = 0.32), arterial elasticity (r = 0.24), total cholesterol/HDL-c ratio (r = -0.22), and body fat% (r = -0.24) were correlated with ARTEwalk. The ARTEwalk index may offer utility in detecting possible differences in physical activity volume among postmenopausal women and appears better associated with cardiometabolic biomarkers compared with AEE or PAL.
Trial registration: ClinicalTrials.gov NCT01031394.
Keywords: aging; cardiovascular; doubly labeled water; exercise; mobility.