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

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 (VO2peak) 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 VO2peak 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 VO2peak.