Prediction of oxygen uptake at peak exercise in patients with inflammatory bowel disease using submaximal cardiopulmonary exercise testing and the steep ramp test as a practical field test

Purpose To develop predictive equations for oxygen uptake at peak exercise (VO 2peak ) measured during a cardiopulmonary exercise test (CPET) for patients with inflammatory bowel disease (IBD) using submaximal CPET-derived parameters and the steep ramp test, along with demographic and clinical characteristics. Methods This study included patients with IBD in remission or with mild-to-moderate disease activity who performed a CPET and a steep ramp test within 14 days. Submaximal CPET-derived parameters included oxygen uptake (VO 2 ) at the ventilatory anaerobic threshold (VAT) and oxygen uptake efficiency slope (OUES), while the outcome of the steep ramp test was the work rate achieved at peak exercise (WR peak ). Results Predictive regression equations with submaximal VO 2 at the VAT and with OUES, when combined with age and body fat percentage, explained >89% of the variance in VO 2peak (optimism-adjusted R 2 = 0.895 and 0.938). Predictive capacity increased when both VO 2 at the VAT and OUES were combined in a predictive regression equation, together with age, body fat percentage, and clinically active disease (optimism-adjusted R 2 = 0.951). Steep ramp test WR peak explained 89% of the variance in VO 2peak (optimism-adjusted R 2 = 0.892). Conclusion The highly predictive equations developed in this study support the use of the submaximal CPET and the steep ramp test as alternatives for assessing VO 2peak in patients with IBD in remission or with mild-to-moderate disease activity in clinical and research settings.