Myers J, Walsh D, Buchanan N, Froelicher V F
Cardiology Department, Long Beach VA Medical Center, Calif. 90822.
Chest. 1989 Dec;96(6):1312-6. doi: 10.1378/chest.96.6.1312.
The failure of oxygen uptake to increase with increasing work has been considered a marker of the limits of the cardiopulmonary system for many years. However, the concept has suffered from inconsistencies in definition, criteria, and data sampling, all of which affect the interpretation of the relation between changes in work and oxygen uptake. To evaluate the response and reproducibility of the slope in oxygen uptake at peak exercise, six subjects (mean age, 33 +/- 6 years) performed two individualized ramp treadmill tests on separate days. During exercise, oxygen uptake (for a given sample of 30 eight-breath running averages) was regressed with time and the slope was calculated. Maximal oxygen uptake, maximal heart rate and maximal perceived exertion were reproducible from day 1 to day 2 (mean difference, 0.4 ml/kg/min, 1.0 beats per minute, and 0.2 for maximal oxygen uptake, heart rate, and maximal perceived exertion, respectively [not significant]). Considerable variability in the slopes was observed during each test and from day to day. This occurred despite the use of large gas exchange samples, averaging techniques, and constant, consistent changes in external work. A plateau, defined as the slope of an oxygen uptake sample at peak exercise that did not differ significantly from a slope of zero, was not a consistent finding within subjects between days. We conclude that marked variability in the slope of the change in oxygen uptake occurs throughout progressive exercise, despite the use of large samples and a linear change in external work. These findings appear to preclude the determination of a plateau by common definitions.
多年来，摄氧量未能随工作量增加而上升一直被视为心肺系统功能极限的一个标志。然而，这一概念在定义、标准和数据采样方面存在不一致之处，所有这些都会影响对工作量变化与摄氧量之间关系的解读。为了评估峰值运动时摄氧量斜率的反应性和可重复性，6名受试者（平均年龄33±6岁）在不同日期进行了两次个性化的斜坡跑步机测试。运动期间，对摄氧量（针对30个八次呼吸平均量的给定样本）与时间进行回归分析并计算斜率。第一天到第二天，最大摄氧量、最大心率和最大主观用力程度具有可重复性（平均差异分别为0.4毫升/千克/分钟、每分钟1.0次心跳以及最大摄氧量、心率和最大主观用力程度分别为0.2[无显著性差异]）。在每次测试期间以及不同日期之间，观察到斜率存在相当大的变异性。尽管使用了大量气体交换样本、平均技术以及外部工作量持续、一致的变化，但这种情况仍然发生。将峰值运动时摄氧量样本的斜率定义为与零斜率无显著差异的平台期，在不同日期的受试者之间并非一致的发现。我们得出结论，尽管使用了大量样本且外部工作量呈线性变化，但在整个渐进性运动过程中，摄氧量变化斜率存在显著变异性。这些发现似乎排除了根据通用定义确定平台期的可能性。
