Evaluation of non-exercise regression equations in prediction of VO2max in healthy children and adolescents boys: cross-validation of non-native equations by the respiratory gas analysis criterion method

Accurate and fast estimation of maximal oxygen uptake (VO2max) as an indicator of cardio-respiratory fitness (CRF) by regression equations without exercise tests in large populations is of great importance in the field of health and sport sciences. Therefore, the aim of this study was to evaluate the cross-validation of the non-native non-exercise (N-EX) regression equations in estimating VO2max of healthy and adolescent boys using the standard method of respiratory gas analysis.

This research was a cross-sectional study in which 349 healthy boys children and adolescents (age: 12.49±2.72 year, BMI: 20.13±4.70 kg/m2 and VO2max: 41.50±6.47 ml/kg/min) were participated. VO2max was measured on a treadmill by the respiratory gas analysis in modified Bruce exercise test (criterion method) and then estimated by three non-native N-EX regression equations. To evaluate the cross-validation the validity of the N-EX regression equations, Pearson correlation, paired sample t-test and Bland-Altman agreement were used for extraction of results.

A significant correlation was observed between VO2max measured by criterion method and N-EX equations (R=0.63 - 0.73, p<0.01). However, a significant difference (p<0.01) was observed between VO2max of criterion method and predicted VO2max by N-EX regression equations (mean difference=6.4–11.69 ml/ kg/min). Also, the Bland-Altman plot showed low agreement between measured and predicted VO2max.

The nonnative N-EX regression equations studied in the present research do not have the necessary accuracy to estimate the VO2max of in healthy children and adolescent boys. Therefore, it seems necessary to verify foreign N-EX VO2max regression equations before use in the Iranian population.