Predicting VO2max using 3MISP and CPET

This cross-sectional study was approved by the Institutional Review Board (IRB) of the Industrial Technology Research Institute (IRB No: IRB-APP-F02-106-009). The study protocol included two 3MISP tests (3MISP_30s and 3MISP_60s) at a given step count (360 steps) with different frequency sequences, and a graded CPET. In this study, a Polar H10 Heart Rate Monitor (Polar Electro Oy, Finland) was used to continuously monitor the heart rate responses of the participants during the CPET and 3MISP tests. The VO_2max of the participants was directly measured by CPET to exhaustion on an electromagnetic bicycle ergometer (Excalibur Sport Ergometer, Lode BV, The Netherlands) and cardiopulmonary exercise testing system (Vmax Encore 29 System, VIASYS Healthcare Inc., Yorba Linda, CA, USA). Because there is a significant correlation between the directly measured VO_2max value and the heart rate change during the 3MISP tests [30 (link),31 (link)], this study used 3MISP-heart rate (HR) as a predictor of VO_2max and combined age, gender, and physical characteristics to establish two VO_2max prediction models (the 3MISP_30s and 3MISP_60s models). To evaluate the reliability and validity of these two VO_2max prediction models, this study used the predicted residual error sum of squares (PRESS) cross-validation procedure to verify the models.