A prediction equation for the estimation of cardiorespiratory fitness using an elliptical motion trainer

Objective: In the United States of America, 6.2 million individuals are using elliptical motion trainers in fitness centres. However, graded exercise test protocols to estimate peak oxygen consumption (VO_2peak) using elliptical motion trainers have not been developed for the general population. Methods: Fifty-nine subjects (mean age: 23.5 ± 4.1 years) were randomly divided into a validation (VAL: n = 39) or cross-validation (XVAL: n = 20) group. Peak oxygen consumption (ml·kg^-1·min^-1) was measured via indirect calorimetry on an elliptical motion trainer for both groups. Subjects exercised at 150 strides·min^-1 against a resistance of four and a crossramp of 8%. The resistance was increased every two minutes by two units until exhaustion. For the VAL group, a stepwise regression analysis was used to predict VO_2peak from resistance, maximal heart rate (HR_max), body mass index (BMI), height and gender (female = 0, male = 1). Results: The prediction equation derived from this study was VO_2peak (ml·kg^-1.min^-1) = 187.39403 + 12.97271 (gender) - 1.45311 (height) - 1.21604 (BMI) - 0.19613 (HR_max) + 1.57093 (resistance) (R² = 0.76, SEE = 4.47, p < 0.05). Using this equation, the predicted VO_2peak of the XVAL group was 45.18 ± 6.42 ml·kg^-1·min^-1, while the measured VO_2peak was 43.55 ± 6.23 ml·kg^-1·min^-1 Conclusion: No significant difference was found between the measured and predicted VO_2peak in the XVAL group. Therefore, it appears this protocol and equation will allow individuals to accurately estimate their VO_2peak without using direct calorimetry. However, future studies should investigate the validity of this protocol with diverse populations.