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The ARTE index: Characterizing free‐living physical activity and indices of cardio‐metabolic health among postmenopausal women
Author(s) -
Altherr Cody A.,
Baranauskas Marissa N.,
Hunter Gary R.,
Martins Catia,
Carter Stephen J.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.02497
Subject(s) - doubly labeled water , percentile , cardiorespiratory fitness , medicine , body mass index , vo2 max , energy expenditure , physical activity level , physical activity , mathematics , statistics , physical therapy , endocrinology , blood pressure , heart rate
Purpose The doubly‐labeled water (DLW) technique is the gold‐standard used to objectively measure free‐living activity energy expenditure (AEE), however; it does not account for differences in body size or locomotion economy. Whereas the physical activity level (PAL) index, calculated from the ratio of total energy expenditure (TEE) and resting energy expenditure (REE), is employed to adjust for body size – it also does not account for variance in energy expenditure attributed to locomotion economy. Alternatively, the activity‐related time equivalent (ARTE) circumvents the limitations of AEE and PAL. In the present work, DLW was used to compare AEE, PAL, and variations of the ARTE index among a cohort of postmenopausal women dichotomized above/below the 50 th percentile of normative data for body fat%. Correlations of AEE, PAL, and ARTE to measures of cardio‐metabolic health including arterial elasticity, body fat% and cardiorespiratory fitness (V̇O 2max ) were also performed. Methods Ninety‐two, healthy postmenopausal women (65+/−4 years) were recruited to measure free‐living AEE over a 14‐day period using DLW. TEE was reduced by 10% to account for the thermogenesis of feeding whereas AEE was calculated by subtracting REE from adjusted‐TEE. PAL was calculated from the ratio of TEE/REE. ARTE 4act was calculated by dividing AEE by the average energy expenditure of non‐graded walking, graded walking, stair climbing, and a carrying task. AEE divided by the average energy expenditure of non‐graded walking was used to calculate ARTE walk . Arterial elasticity was performed using pulse contour analysis from the radial artery. Dual‐energy X‐ray absorptiometry was used to estimate body fat% whereas a modified‐Balke protocol was used to measure V̇O 2max . Between‐group comparisons were performed using independent t ‐tests and Pearson’s correlation were used to evaluate relationships. Results Between‐group differences were not detected for AEE, PAL, or the ARTE 4act . However, women with less percent body fat (i.e., < 50 th percentile) exhibited greater activity as evidenced by the ARTE walk (min·day −1 ) (255+/−154 vs. 193+/−130; p < 0.05). Though AEE and PAL did not correlate with any cardio‐metabolic variables, ARTE 4act was related to arterial elasticity ( r = 0.24) and V̇O 2max ( r = 0.27) while ARTE walk was related to arterial elasticity ( r = 0.27), body fat% ( r = −0.24), and V̇O 2max ( r = 0.32). Conclusions Consistent with the ARTE walk , adjustments for energetic cost of non‐graded walking may improve the sensitivity of AEE for detecting differences in free‐living physical activity and parameters of cardio‐metabolic health – known to be critical for overall well‐being. Support or Funding Information This investigation was supported by the following grants from the National Institutes of Health: R01AG027084‐01, R01AG027084‐S, P30DK056336, P60DK079626, and UL1RR025777.