A general prediction formula has been derived for predicting maximal aerobic power (VO2 max) based on nonlinear relationship between aerobic stress and cardiorespiratory strains imposed on the subject during submaximal exercise on bicycle ergometer. The validity of the prediction formula has been tested for the data consisting of 135 observations on 45 moderately active young subjects who were asked to exercise on the bicycle ergometer at three submaximal and one maximal work rate. It has been found that product moment correlations of aerobic stress with respiratory strain and cardiac strain expressed logarithmically were 0.7651 and 0.7457 respectively. These correlations were significant (P less than 0.001). The multiple correlation between observed and estimated aerobic stress expressed logarithmically in terms of cardiorespiratory strains was 0.8142 which was significant (P less than 0.001). There is a significant improvement in multiple correlation from the product moment correlations of aerobic stress with either of two strains expressed logarithmically. It has been conclusively established that combined index of cardioresiratory strains will be better predictor of aerobic stress than either respiratory or cardiac strain alone as commonly employed by several workers.