Validity and reproducibility of VO₂ max testing in a respiration chamber

The aim of this study was to investigate whether VO₂ max can be accurately measured in a respiration chamber. Thirty participants aged 23.4 ± 3.9 years with a wide range in VO₂ max were included. Participants performed four incremental cycle ergometer tests (VO₂ max) with a minimum of 5 days between tests. These tests consisted of one familiarization test with face mask, followed by two VO₂ max tests in the respiration chamber and one test with face mask in randomized order. Oxygen consumption and CO₂ production were measured continuously using Omnical (Maastricht University, the Netherlands) gas analysis system. The mean VO₂ max was 3634 ± 766 ml, which resulted in mean VO₂ max per lean body mass of 60.8 ± 8.0 ml/kg. Repeated respiration chamber tests showed a high concordance, and no significant differences were detected between tests (Lin's concordance correlation coefficient (Rc) = 0.99; ∆70 ± 302 ml/min; p = .38). There was high concordance between the mean VO₂ max from both respiration chamber tests and the mean face mask tests, and no significant difference (Rc = 0.99; ∆41 ± 173 ml/min; p = .22) was observed. The Bland-Altman plots showed no proportional bias between different tests. In conclusion, the respiration chamber has been found to be a valid and reproducible method for measuring VO₂ max. New research opportunities are possible in the respiration chamber, such as maximal exercise testing during 24-hour measurements.