Abstract: Objective:To study the reliability of prediction of maximal oxygen uptake (VO2 max) from sub-maximal ratings of perceived exertion (RPE) and heart rate (HR) elicited during a graded treadmill exercise test.Methods:22physical education college students (10male and 12 female) performed a incremental treadmill exercise test at moderate intensity range, and the RPE level, heart rate and oxygen uptake at the different exercise stages were measured.The RPE9and RPE13, RPE9and RPE15were used to establish the linear model of RPE and oxy- gen uptake respectively, then used the linear model that had been established to determine the oxygen uptake of RPE20 and RPE19 corresponding, which is the maximal oxygen uptake predic- tion value.Similarly, the RPE9and RPE13, RPE9and RPE15were used to establish the line- ar model ofVO2 and HR respectively, then used the linear model that had been established to determine the oxygen uptake of the maximum heart rate, which is the maximal oxygen uptake prediction value, and the maximum heart rate was calculated using 220-age and 206.9-0.67 ×age.Results:1) comparing the predicted values of the RPE and HR with the test values, theVO2 max prediction values from RPE9-13 (RPE20) (denotation that linear equation was been build using RPE9and RPE13, and the oxygen uptake at RPE20 as the prediction value of VO2 max, the same below) , RPE9-15 (RPE20) , RPE9-15 (RPE19) , HR9-13 (220-age) , HR9-13 (206.9-0.67×age) and HR9-15 (220-age) were not significantly different with the actual test.2) from the Pearson's correlation analysis, theVO2 max prediction value from RPE9-13 (RPE20) , RPE9-13 (RPE19) , RPE9-15 (RPE20) and RPE9-15 (RPE19) has certain relation with the actual test value, and the correlation coefficient are higher between theVO2 max prediction val- ue from RPE9-13 (RPE20) and RPE9-13 (RPE19) (r>0.90, P<0.001) .The heart rate predic- tedVO2 max value and actual test is a low correlation coefficient (r<0.60) .3) from the in- tra-class correlation analysis, the intra-class correlation coefficients betweenVO2 max prediction value from RPE9-13 (RPE20) , RPE9-13 (RPE19) , RPE9-15 (RPE20) and RPE9-15 (RPE19) and actual test value were above 0.80 (P<0.01) , and the intra-class correlation coefficients are higher between theVO2 max prediction value from RPE9-13 (RPE20) and RPE9-13 (RPE19) and actual test value (ICC>0.90, P<0.001) .But the intra-class correlation coefficient between the VO2 max prediction value from heart rate and the actual test value is lower.4) the analysis of Bland-Altman and limits of agreement (95%LoA, bias±1.96×SDdiff) showed the range of limits of agreement between the predicted value from heart rate and the actual test value is wide, but that is relatively narrow between the predicted value from RPE and the actual test value, and the best consistency is RPE9-13 (RPE20) , the 95%LoA were 0.49±5.08 (male) , -0.43±6.25 (female) and-0.01±5.68 (integrated) .Conclusion:using the RPE level at the different exercise stages during agraded treadmill exercise test in sub-maximal intensity range to predict theVO2 max has certain reliability, where the RPE9-13 extension to the RPE20 to predicted VO2 max is highest accuracy.