Evaluating maximal oxygen uptake in exercise-based cardiac rehabilitation

Maximal oxygen uptake (VO₂max) is a strong, independent predictor of both all-cause and disease-specific mortality, making it a key health and performance marker for individuals with heart disease. While cardiopulmonary exercise testing is the gold standard for determining VO₂max, its use in primary healthcare settings remains underexplored. This study aims to evaluate standard criteria for assessing VO₂max in individuals enrolled in cardiac rehabilitation.

A cross-sectional study was conducted in a primary healthcare setting. Participants who referred to exercise-based cardiac rehabilitation underwent a cycle ergometer exercise test to determine VO₂max. The primary validation criterion was the presence of a VO₂ plateau, defined by cut-offs of ≤50 and ≤100 mL O₂/min. Secondary criteria included respiratory exchange ratio, rate of perceived exertion, and maximal heart rate.

Among 93 participants, 88% reached a VO₂ plateau using the ≤100 mL cut-off. Additionally, 61% met at least two secondary criteria, indicating maximal effort.

In primary healthcare cardiac rehabilitation, a cut-off of ≤100 mL may be suitable for identifying a VO₂ plateau. For those not reaching a plateau, maximal effort can be assessed using RER ≥1.15 and RPE ≥17 as criteria.