The effects of a single bout of exercise on resting energy expenditure and respiratory exchange ratio

We investigated the effects of a single bout of aerobic and resistance exercise of similar relative intensity and duration on resting energy expenditure (REE) and substrate utilisation. Ten young healthy males volunteered [age 22 (1.8) years, weight 76 (7.9) kg, height 176 (4.1) cm, percentage body fat 10.5 (4.0)%; mean (SEM)]. They randomly underwent three conditions in which they either lifted weights for 60 min at 70–75% of 1-RM (WL), ran for 60 min at 70–75% of maximal oxygen intake (R) or did not exercise (C). REE and substrate utilisation, determined via respiratory exchange ratio (R), were measured prior to exercise, and 10, 24, 48 and 72 h post-exercise. It was revealed that REE was significantly elevated (P<0.05) 10 and 24 h after the end of WL [2,124 (78) and 2,081 (76) kcal, respectively] compared to pre-exercise [1,972 (82) kcal]. REE was also significantly increased (P<0.05) 10 and 48 h after the completion of R [2,150 (73) and 1,995 (74) kcal, respectively] compared to pre-exercise data [1,862 (70) kcal]. R was lower 10 and 24 h following either WL or R [0.813 (0.043); 0.843 (0.040) and 0.818 (0.021); 0.832 (0.021), respectively] compared to baseline measurements [0.870 (0.025) and 0.876 (0.04), respectively]. Creatine kinase was significantly elevated (P<0.05) 24 h after both WL and R, whereas delayed onset muscle soreness became significantly elevated (P<0.05) 24 h after only WL. There were no significant changes for any treatment in thyroid hormones (T₃ and T₄). These results suggest that a single bout of either WL or R exercise, characterised by the same relative intensity and duration, increase REE and fat oxidation for at least 24 h post-exercise.