Use of the Wasserman equation in optimization of the duration of the power ramp in a cardiopulmonary exercise test: a study of Brazilian men

This study aimed to analyze the agreement between measurements of unloaded oxygen uptake and peak oxygen uptake based on equations proposed by Wasserman and on real measurements directly obtained with the ergospirometry system. We performed an incremental cardiopulmonary exercise test (CPET), which was applied to two groups of sedentary male subjects: one apparently healthy group (HG, n=12) and the other had stable coronary artery disease (n=16). The mean age in the HG was 47±4 years and that in the coronary artery disease group (CG) was 57±8 years. Both groups performed CPET on a cycle ergometer with a ramp-type protocol at an intensity that was calculated according to the Wasserman equation. In the HG, there was no significant difference between measurements predicted by the formula and real measurements obtained in CPET in the unloaded condition. However, at peak effort, a significant difference was observed between oxygen uptake ( V ˙O2)peak(predicted) and V ˙O2peak(real) (nonparametric Wilcoxon test). In the CG, there was a significant difference of 116.26 mL/min between the predicted values by the formula and the real values obtained in the unloaded condition. A significant difference in peak effort was found, where V ˙O2peak(real) was 40% lower than V ˙O2peak(predicted) (nonparametric Wilcoxon test). There was no agreement between the real and predicted measurements as analyzed by Lin’s coefficient or the Bland and Altman model. The Wasserman formula does not appear to be appropriate for prediction of functional capacity of volunteers. Therefore, this formula cannot precisely predict the increase in power in incremental CPET on a cycle ergometer.

本研究旨在对比Wasserman提出的公式法测算的无负荷摄氧量与峰值摄氧量，与直接采用心肺运动测功系统（ergospirometry system）实测得到的真实值之间的一致性。我们对两组久坐男性受试者实施了递增式心肺运动试验（incremental cardiopulmonary exercise test, CPET）：一组为外观健康受试者组（HG，n=12），另一组为稳定型冠状动脉疾病受试者组（CG，n=16）。健康组的平均年龄为47±4岁，冠状动脉疾病组的平均年龄为57±8岁。两组均采用斜坡式负荷方案，在自行车测功仪上完成CPET，负荷强度依据Wasserman公式计算确定。在健康组中，无负荷状态下公式预测摄氧量与CPET实测值无显著差异；但在峰值运动状态下，预测峰值摄氧量（V̇O₂peak(predicted)）与实测峰值摄氧量（V̇O₂peak(real)）之间存在显著差异（非参数Wilcoxon检验（nonparametric Wilcoxon test））。在冠状动脉疾病组中，无负荷状态下公式预测值与CPET实测值间存在116.26 mL/min的显著差异；峰值运动状态下同样存在显著差异，实测峰值摄氧量较预测值低40%（非参数Wilcoxon检验）。通过Lin相关系数（Lin’s coefficient）与Bland-Altman模型（Bland and Altman model）分析显示，真实值与预测值之间无一致性。Wasserman公式似乎并不适用于预测受试者的运动功能容量，因此该公式无法精准预测自行车测功仪递增式CPET中的功率增幅。