ALTERATIONS IN RESTING METABOLIC-RATE AS A CONSEQUENCE OF 20 WK OF ENDURANCE TRAINING - THE HERITAGE FAMILY STUDY

This study determined the effects of endurance exercise training on th e resting metabolic rate (RMR). It was hypothesized that the RMR would be increased posttraining, but that this increase would reflect the i nfluence of the last exercise bout, not a chronic adaptation to exerci se training. Seventy-four subjects (40 men and 37 women) aged 17-63 y participated in a 20-wk endurance training program. RMR and maximal ox ygen uptake (V over dot O(2)max) were each measured on 2 separate days both pre- and posttraining; the posttraining RMR measurements were ta ken 24 and 72 h after the last exercise bout, There were small but sig nificant changes posttraining in relative body fat (-1.0%), fat mass ( -0.6 kg), and fat-free mass (0.7 kg) and a 17.9% increase in V over do t O(2)max. The RMR remained unchanged posttraining, both 24 and ?2 h a fter the last exercise bout, even when the data were adjusted to accou nt for the potential confounding effects of age, sex, body composition , and V over dot O(2)max. In conclusion, 20 wk of endurance exercise t raining had no effect on the RMR even in the presence of small changes in body composition and a large increase in V over dot O(2)max.