PurposeThis study assessed the utility of the Children’s Effort Rating Table (CERT) and the Eston–Parfitt (EP) Scale in estimating peak oxygen uptake () in children, during cardiopulmonary exercise testing (CPET) on a treadmill.MethodsFifty healthy children (n = 21 boys; 9.4 ± 0.9 years) completed a continuous, incremental protocol until the attainment of . Oxygen uptake () was measured continuously, and ratings of perceived exertion (RPE) were estimated at the end of each exercise stage using the CERT and the EP Scale. Ratings up to- and including RPE 5 and 7, from both the CERT (CERT 5, CERT 7) and EP Scale (EP 5, EP 7), were linearly regressed against the corresponding , to both maximal RPE (CERT 10, EP 10) and terminal RPE (CERT 9, EP 9).ResultsThere were no differences between measured- and predicted from CERT 5, CERT 7, EP 5 and EP 7 when extrapolated to either CERT 9 or EP 9 (P > 0.05). Pearson’s correlations of r = 0.64–0.86 were observed between measured- and predicted , for all perceptual ranges investigated. However, only EP 7 provided a small difference when considering the standard error of estimate, suggesting that the prediction of from EP 7 would be within 10 % of measured .ConclusionsAlthough robust estimates of may be elicited using both the CERT and EP Scale during a single CPET with children, the most accurate estimates of occur when extrapolating from EP 7.