Validation of Francis Step Protocol by Respiratory Gases Analyses and Design Native Equation to Estimate Aerobic Capacity in Iranian Boys

Abstract

Introduction: Accurate, safe and simple measurement of the cardio-respiratory fitness is important in clinical and research settings. Therefore, the assessing the validity of exercise testsoutside the laboratory environment is important. The aim of this study was to assess the validity and reliability of the Francis steps protocol based on respiratory gases analysis method and design a native equation to estimate aerobic capacity in Iranian boys.

Methods: Maximum oxygen consumption was measured in two ways of maximal standard test on treadmill with direct measurement of respiratory gases and Francis steps tests by Ergostep electromechanical bench with adjustable height from 138 students ranging from 8 to 13 years old. To assess the validity and reliability of the Francis steps protocol, Pearson’s correlation coefficient and intra-class correlation coefficient (ICC) was used.

Results: Significant correlation between maximal oxygen uptake measured by the direct method and the results obtained through the steps protocol of Francis was observed (P<0.001, r=0.85). Francis steps test reliability was observed in excellent level (ICC=0.96). Iranian boys predictive equation for maximum oxygen consumption using age, BMI, ending heart rate, of the Francis steps test was designed (P<0.001, SEE=2.61, r=0.88).

Conclusion: Due to the high validity of adjustable height Francis step test, it can be used for estimating the performance of the cardio respiratory system of the boys. Thus application of native equation of Francis step test in Iranian boys, in clinical and exercise setting and in health sciences studies, can be used.