Validity and feasibility of four standardized aerobic fitness tests in patients with depression: A cross-sectional study

The objective of this study was to examine the validity and feasibility of four standardized aerobic fitness tests to either measure V˙ O2peak or to estimate V˙ O2max (e V˙ O2max) in patients with major depression disorder (MDD). To this end, all subjects (n = 43) performed one maximal cardiopulmonary exercise test with gas exchange measurement (CPET) on a bicycle ergometer. Additionally, three submaximal tests (Åstrand-Rhyming bicycle ergometer test [ART], Physical work capacity test [PWC], and 6-min walk test [6MWT]) were performed within two weeks in counterbalanced order. e V˙ O2max from the submaximal tests was compared to the measured V˙ O2peak from CPET using rANOVAs, Bland-Altman plots, and correlation analyses. Feasibility outcomes (e.g., perceived exertion, discomfort, pretest anxiety, etc.) were compared via rANOVAs. On group level, e V˙ O2max estimated submaximally via ART and PWC did not differ from the CPET-based V˙ O2peak, whereas there was a bias in the 6MWT, as differences of the means increased in participants with higher V˙ O2peak. During CPET, only 56% achieved a primary or secondary criterion of maximum (physiological) exertion. On the group level, V˙ O2peak and e V˙ O2max determined with the different tests showed a sufficient degree of agreement (r ≥ 0.54, ICCs≥0.66, p