Effect of endurance training on sedentary energy expenditure measured in a respiratory chamber

The effect of endurance training on 24-h energy expenditure (EE), basal metabolic rate (BMR), sleeping metabolic rate (SMR), and the thermic effect of food (TEF) was assessed in a respiratory chamber where only spontaneous physical activity (SPA) was allowed. Results from 20 highly trained male endurance athletes (25 +/- 5 yr, 178 +/- 7 cm, 70 +/- 8 kg body wt, 64 +/- 7 kg fat-free mass) were compared with those of 43 untrained males who were matched for age (28 +/- 6 yr), height (175 +/- 5 cm), weight (73 +/- 13 kg), and fat-free mass (62 +/- 8 kg). Subjects were admitted to a metabolic ward, fed a weight-maintenance diet, and refrained from physical activity for at least 2 days before measurements. No significant differences were found with respect to 24-h EE (2,126 +/- 186 vs. 2,154 +/- 245 kcal), BMR (1,808 +/- 342 vs. 1,709 +/- 329 kcal), SMR (1,523 +/- 120 vs. 1,555 +/- 188 kcal), or TEF (24.9 +/- 9.2 vs. 21.3 +/- 6.7% of ingested calories; these values included the energy cost of arousal) between trained and untrained subjects, respectively, before or after adjusting for differences in body composition. Neither the 24-h respiratory quotient nor the level of SPA differed between the two groups. No relationship was found between maximal aerobic capacity and metabolic rate adjusted for differences in fat-free mass and fat mass. These results do not support an effect of fitness level on EE measured under sedentary conditions.(ABSTRACT TRUNCATED AT 250 WORDS)