Assessing Maximal Exercise Capacity: Peak Work or Peak Oxygen Consumption?

作者：Kaminsky David A^*; Knyazhitskiy Alexey; Sadeghi Ali; Irvin Charles G

来源：Respiratory Care, 2014, 59(1): 90-96.

DOI：10.4187/respcare.02253

• cardiopulmonary exercise test
• maximal oxygen consumption
• anaerobic threshold
• work capacity

BACKGROUND: Exercise capacity assessed by cardiopulmonary exercise testing is usually measured by peak oxygen consumption ((V) over dot(O2)). However, not uncommonly, patients achieve a relatively higher work load (peak work) compared to their peak (V) over dot(O2). In these situations it is difficult to know which parameter to use in assessing exercise capacity. The purpose of this study was to determine whether there are distinguishing physiological characteristics of patients with discordance between percent-of-predicted peak work versus peak (V) over dot(O2), in order to understand how to use these measurements in interpreting exercise capacity. METHODS: We conducted a retrospective study of 172 cardiopulmonary exercise tests performed at our institution between 2003 and 2010. RESULTS: The subjects in the higher peak work group demonstrated higher ventilatory efficiency (lower slope of minute ventilation to carbon dioxide production) and lung FEV1 and FVC), a greater breathing reserve (higher breathing reserve, lower (V) over dot(E)/maximal voluntary ventilation), and achieved a higher maximal heart rate. Subjects in the higher maximum (V) over dot(O2) group were heavier, had lower ventilatory efficiency, and had a reduced breathing reserve. Multivariate logistic regression analysis showed that the predominant independent factors associated with group assignment were body mass index, breathing reserve, and peak heart rate. The subjects with higher percent-of-predicted peak work than peak (V) over dot(O2) had a lower body mass index, a greater breathing reserve, and a higher peak heart rate. CONCLUSIONS: The observation that there are distinguishing physiological features between those who have a higher peak work and those who have higher peak (V) over dot(O2) provides insight into the underlying processes determining maximal exercise capacity.

• 出版日期2014-1