Influence of aerobic capacity, body composition, and thyroid hormones on the age-related decline in resting metabolic rate.
It has been suggested that changes in fat-free weight may not fully explain the decline of resting metabolic rate (RMR) that occurs with aging. We therefore examined the hypothesis that a reduction in maximal aerobic capacity (VO2max) may partially explain the lower RMR in older men, after accounting for differences in fat-free weight and fat weight. We also considered differences in energy intake and plasma thyroid hormones as possible modulators of the age-related decline in RMR in men. Three-hundred healthy men (aged 17 to 78 years) were characterized for: (1) RMR (kcal/min) from indirect calorimetry; (2) body composition from underwater weighing; (3) maximal aerobic capacity from a test of VO2max; (4) plasma thyroid hormones (total triiodothyronine [T3], free T3, total thyroxine [T4], and free T4); and (5) estimated energy intake (kcal/d) from a 3-day food diary. A curvilinear decline of RMR with age was found (P less than .01), in which no relationship was found in men less than 40 years of age (r = .10, slope = 0.002 kcal/min/yr), whereas in men older than 40 years, RMR was negatively related to age (r = -.52, slope = -0.008 kcal/min/yr). After statistical control for differences in fat-free weight and fat weight, a negative relationship between age and RMR persisted (partial r = -.30, P less than .01). It was only after control for fat-free weight, fat weight, and VO2max (partial r = -.10, P greater than .05) that no association between age and RMR was noted.(ABSTRACT TRUNCATED AT 250 WORDS)
Poehlman
E T
ET
Department of Medicine, College of Medicine, University of Vermont, Burlington 05405.
Berke
E M
EM
Joseph
J R
JR
Gardner
A W
AW
Katzman-Rooks
S M
SM
Goran
M I
MI
D000293:Adolescent; D000328:Adult; D000332:Aerobiosis; D000368:Aged; D000375:Aging / Q000378:metabolism*; D001481:Basal Metabolism; D001823:Body Composition; D015331:Cohort Studies; D002149:Energy Intake; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D010807:Physical Endurance; D013223:Statistics as Topic; D013963:Thyroid Hormones / Q000097:blood*
D013963:Thyroid Hormones