Confirming the attainment of maximal oxygen uptake within special and clinical groups: A systematic review and meta-analysis of cardiopulmonary exercise test and verification phase protocols.

ABSTRACT

BACKGROUND AND AIM: A plateau in oxygen uptake ([Formula see text]) during an incremental cardiopulmonary exercise test (CPET) to volitional exhaustion appears less likely to occur in special and clinical populations. Secondary maximal oxygen uptake ([Formula see text]) criteria have been shown to commonly underestimate the actual [Formula see text]. The verification phase protocol might determine the occurrence of 'true' [Formula see text] in these populations. The primary aim of the current study was to systematically review and provide a meta-analysis on the suitability of the verification phase for confirming 'true' [Formula see text] in special and clinical groups. Secondary aims were to explore the applicability of the verification phase according to specific participant characteristics and investigate which test protocols and procedures minimise the differences between the highest [Formula see text] values attained in the CPET and verification phase. METHODS: Electronic databases (PubMed, Web of Science, SPORTDiscus, Scopus, and EMBASE) were searched using specific search strategies and relevant data were extracted from primary studies. Studies meeting inclusion criteria were systematically reviewed. Meta-analysis techniques were applied to quantify weighted mean differences (standard deviations) in peak [Formula see text] from a CPET and a verification phase within study groups using random-effects models. Subgroup analyses investigated the differences in [Formula see text] according to individual characteristics and test protocols. The methodological quality of the included primary studies was assessed using a modified Downs and Black checklist to obtain a level of evidence. Participant-level [Formula see text] data were analysed according to the threshold criteria reported by the studies or the inherent measurement error of the metabolic analysers and displayed as Bland-Altman plots. RESULTS: Forty-three studies were included in the systematic review, whilst 30 presented quantitative information for meta-analysis. Within the 30 studies, the highest mean [Formula see text] values attained in the CPET and verification phase protocols were similar (mean difference = -0.00 [95% confidence intervals, CI = -0.03 to 0.03] L·min-1, p = 0.87; level of evidence, LoE strong). The specific clinical groups with sufficient primary studies to be meta-analysed showed a similar [Formula see text] between the CPET and verification phase (p > 0.05, LoE limited to strong). Across all 30 studies, [Formula see text] was not affected by differences in test protocols (p > 0.05; LoE moderate to strong). Only 23 (53.5%) of the 43 reviewed studies reported how many participants achieved a lower, equal, or higher [Formula see text] value in the verification phase versus the CPET or reported or supplied participant-level [Formula see text] data for this information to be obtained. The percentage of participants that achieved a lower, equal, or higher [Formula see text] value in the verification phase was highly variable across studies (e.g. the percentage that achieved a higher [Formula see text] in the verification phase ranged from 0% to 88.9%). CONCLUSION: Group-level verification phase data appear useful for confirming a specific CPET protocol likely elicited [Formula see text], or a reproducible [Formula see text], for a given special or clinical group. Participant-level data might be useful for confirming whether specific participants have likely elicited [Formula see text], or a reproducible [Formula see text], however, more research reporting participant-level data is required before evidence-based guidelines can be given. TRIAL REGISTRATION PROSPERO (CRD42021247658) https//www.crd.york.ac.uk/prospero.