Relation of age and physical exercise status on metabolic rate in younger and older healthy men.

We examined the influence of age and habitual physical exercise level on resting metabolic rate (RMR) and thermic effect of a meal test (TEM) by studying sedentary and physically active younger and older men. RMR was measured using a ventilated hood and TEM for 180 min after ingestion of a liquid meal. RMR, adjusted for fat-free weight (FFW) and percent body fat, was lower in sedentary older men relative to the other three groups. TEM (kcal.180 min-1) was highest in active younger (77.3 +/- 3.7) and active older men (69.8 +/- 7.0) relative to sedentary younger (53.1 +/- 4.0) and sedentary older men (51.5 +/- 6.9). TEM was not related to age or body composition. A sedentary life style in older men may be associated with a lower RMR, independent of FFW and percent body fat, relative to younger men and older men who regularly exercise. Participation in physical exercise, regardless of age, is associated with a higher TEM.