Body Composition and Cardiorespiratory Fitness vs. 1-MET Value in Older Adults: A Factor Analytic Study.

Abstract

Background: The metabolic equivalent (1-MET) represents the oxygen consumption at rest, reflecting the body's minimal energy needs. Determinants of 1-MET among older adults are yet to be defined. This cross-sectional study examined the association between 1-MET, body size and composition, and cardiorespiratory fitness in older adults using principal component analysis (PCA).

Methods: Fifty-eight participants aged 60 and above (12 males, 75.4 ± 6.5 years) were assessed for 1-MET and peak oxygen consumption (VO_2peak) via indirect calorimetry, and body composition was measured by dual-energy X-ray absorptiometry.

Results: The average 1-MET value (2.3 mL·kg^-1·min^-1) was significantly lower than the reference 3.5 mL kg^-1·min^-1 (p < 0.001). PCA identified two factors accounting for 79.3% of the variance. Factor 1 (51.2% variance) grouped body mass index (BMI), fat mass, and body surface area. Factor 2 (28.1% variance) linked VO_2peak and 1-MET. Results showed that 1-MET was more strongly associated with cardiorespiratory fitness than body size or composition.

Conclusions: Cardiorespiratory fitness seems to be a determinant of the resting metabolic rate in older adults, and lower 1-MET values would be expected in individuals with poorer vs. higher VO_2peak.