Smith, D. A., J. Dollman, R. T. Withers, M. Brinkman, J. P. Keeves, and D. G. Clark. Relationship between maximum aerobic power and resting metabolic rate in young adult women. J. Appl. Physiol. 82(1): 156-163, 1997.The literature is inconclusive as to the chronic effect of aerobic exercise on resting metabolic rate (RMR), and furthermore there is a scarcity of data on young women. Thirty-four young women exhibiting a wide range of aerobic fitness [maximum aerobic power (O_{2 max}) = 32.3-64.8 ml ^· kg^{1 ·} min¹] were accordingly measured for RMR by the Douglas bag method, treadmill O_{2 max}, and fat-free mass (FFM) by using Siri's three-compartment model. The interclass correlation (n = 34) between RMR (kJ/h) and O_{2 max} (ml ^· kg^{1 ·} min¹) was significant (r = 0.39, P < 0.05). However, this relationship lost statistical significance when RMR was indexed to FFM and when partial correlation analysis was used to control for FFM differences. Furthermore, multiple linear-regression analysis indicated that only FFM emerged as a significant predictor of RMR (kJ/h). When high- (n = 12) and low-fitness (n = 12) groups were extracted from the cohort on the basis of O_{2 max} scores, independent t-tests revealed significant between-group differences (P < 0.05) for RMR (kJ ^· kg^{1 ·} h¹) and O_{2 max} (ml ^· kg^{1 ·} min¹) but not for RMR (kJ/h), RMR (kJ ^· kg FFM^{1 ·} h¹), and FFM. Analysis of covariance of RMR (kJ/h) with FFM as the covariate also showed no significant difference (P = 0.56) between high- and low-fitness groups. Thus the results suggest that 1) FFM accounts for most of the differences in RMR between subjects of varying O_{2 max} values and 2) the RMR per unit of FFM in young healthy women is unrelated to O_{2 max}.