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.本研究旨在分析基于Wasserman提出的公式计算得到的无负荷摄氧量、峰值摄氧量，与直接通过运动心肺测试系统（ergospirometry system）实测得到的对应指标之间的一致性。本研究针对两组久坐男性受试者开展递增负荷心肺运动试验（CPET）：一组为外观健康对照组（HG，n=12），另一组为稳定性冠状动脉疾病患者组（CG，n=16）。对照组（HG）受试者的平均年龄为47±4岁，冠状动脉疾病组（CG）受试者的平均年龄为57±8岁。两组受试者均采用基于Wasserman公式计算得到的运动强度，在功率自行车上开展斜坡式递增方案的CPET。在健康对照组中，无负荷状态下公式预测的摄氧量与CPET实测摄氧量之间无显著差异。但在力竭峰值状态下，经非参数Wilcoxon检验显示，预测峰值氧摄入量（V̇O2peak(predicted)）与实测峰值氧摄入量（V̇O2peak(real)）之间存在显著差异。在冠状动脉疾病组中，无负荷状态下公式预测值与CPET实测值之间的差值达116.26 mL/min，且存在显著统计学差异。经非参数Wilcoxon检验，力竭峰值状态下同样存在显著差异：实测峰值氧摄入量较预测值低40%。通过Lin一致性相关系数与Bland-Altman模型（Bland and Altman model）分析显示，实测值与预测值之间不存在一致性。Wasserman公式似乎并不适用于预测受试者的运动功能储备。因此，该公式无法精准预测功率自行车递增负荷CPET中的功率增幅。