Abstract
Introduction: During maximal ramp-incremental exercise (RIE), the oxygen uptake power output relationship (V̇ O₂gain) may deviate from linearity near exhaustion. An increased oxygen cost of ventilation (V̇ O₂VENT) is a plausible but under-quantified contributor. This study tested a non-linear multi-factorial model using measured V̇ O2VENT and six predictors: resting expired ventilation (V̇ E), weight, height, age, V̇ O₂peak, and maximal heart rate (HRMax) to 1) estimate V̇ O₂VENT and its contribution to maximal oxygen uptake (V̇ O₂max) in an independent dataset, and 2) determine whether correcting V̇ O₂ by V̇ O₂VENT (V̇ O₂VCORR) alters V̇ O₂max and V̇ O₂gain estimates.
Methods: Published data from 42 participants (11 females, 31 males; 29 ± 6.5 y; V̇ O₂max = 4.02 ± 1.06 L·min⁻¹) were used to derive the model. Leave-one-out cross-validation (LOOCV) assessed validity, with predictive accuracy and coefficient stability evaluated via bootstrap resampling. The model was applied to an independent RIE dataset to generate V̇ O₂VCORR, compared with uncorrected V̇ O₂ across six %Wpeak intensities using repeated-measures ANOVA and final 30 s slope analysis.
Results: The model explained 81% of V̇ O₂VENT variance (adjusted R² = 0.78 ). V̇ O₂VENT represented 17.43 % ± 3.58 % of V̇ O₂ at V̇ O₂max, Across 35–100 % Wpeak, V̇ O₂VCORR values (L·min⁻¹) increased with intensity [1.77 ± 0.43, 2.68 ± 0.57, 3.43 ± 0.72, 3.72 ± 0.79, 3.84 ± 0.86, and 3.92 ± 0.82) but remained significantly lower than uncorrected V̇ O₂ (p < 0.001), with the final-30 s V̇ O₂ slope attenuated following correction (p = 0.002).
Conclusion: The internally validated model revealed V̇ O₂VENT may contribute to a significant fraction of V̇ O₂ near exhaustion.