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Turkish Journal of Medical Sciences

Abstract

Background/aim: Existing treadmill-based VO₂ prediction models may not accurately estimate submaximal VO₂ in patients with coronary artery disease (CAD), as they are often derived from healthy populations. This study aimed to develop and validate a submaximal VO₂ prediction model derived from healthy individuals and tested for generalizability in CAD patients by incorporating clinically relevant parameters.

Materials and methods: A retrospective analysis was conducted with 101 participants (54 healthy, 47 CAD patients) undergoing cardiopulmonary exercise testing using the modified Bruce protocol. To better represent the submaximal VO₂ reached during exercise, the average VO₂ in the last minute of each stage was used. The model was developed using data from healthy individuals and subsequently validated in the CAD cohort. A linear mixed-effects model was employed to predict VO₂ based on speed, grade, and other confounders, including peak VO₂, body weight, and body mass index (BMI). The model’s performance was evaluated and compared with previously published equations using Bland–Altman plots, mean absolute error (MAE), root mean square error (RMSE), and Lin’s concordance correlation coefficient (CCC).

Results: The final model, including speed, grade, and peak VO2, achieved an R² of 0.83 (95% CI: 0.79, 0.86; f² = 4.88). For CAD patients, the predicted-actual VO₂ difference was –0.05 ± 1.8 mL/kg/min, with MAE and RMSE values of 1.4 and 1.8 mL/kg/min, respectively. The model outperformed reference equations, achieving the highest accuracy (CCC = 0.923) and minimal bias. Incorporating peak VO₂ effectively accounted for exercise response differences between healthy individuals and CAD patients.

Conclusion: A submaximal VO₂ estimation model derived from healthy individuals and validated in CAD patients demonstrated high accuracy. Incorporating peak VO₂ effectively bridged physiological differences, supporting individualized exercise prescriptions in cardiac rehabilitation. However, larger prospective cohorts are warranted to confirm external validity.

Author ORCID Identifier

LEVENT KARATAŞ: 0000-0003-0751-5632

ESRA ORBAK YENİDÜNYA: 0009-0000-8650-002X

NESRİN DEMİRSOY: 0000-0003-4332-6118

DOI

10.55730/1300-0144.6046

Keywords

Cardiac rehabilitation, coronary artery disease, exercise, oxygen uptake, treadmill

First Page

930

Last Page

939

Publisher

The Scientific and Technological Research Council of Türkiye (TÜBİTAK)

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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