Cardiopulmonary exercise testing involves collecting variable breath-by-breath data, sometimes requiring data processing of outlier removal, interpolation, and averaging before later analysis. These data processing choices, such as averaging duration, affect calculated values such as VO2max. However, assessing the implications of data processing without knowing popular methods worth comparing is difficult. In addition, such details aid study reproduction. We conducted a semi-automated scoping review of articles with exercise testing that collected data breath-by-breath from three databases. Of the 8,344 articles, 376 (mean 4.5%, 95% CI: 4.1-5.0%) and 581 (7.0%, 6.4-7.5%) described outlier removal and interpolation, respectively. A random subset of 1,078 articles revealed 60.9% (57.9-63.7%) reported averaging methods. Commonly documented outlier cutoffs were ± 3 or 4 SD (39.1% and 51.6%, respectively). The dominating interpolation duration and procedure were one second (93.9%) and linear interpolation (92.5%). Averaging methods commonly described were 30 (30.9%), 60 (12.4%), 15 (11.6%), 10 (11.0%), and 20 (8.1%) second bin averages. This shows that studies collecting breath-by-breath data often lack detailed descriptions of data processing methods, particularly for outlier removal and interpolation. While averaging methods are more commonly reported, improved documentation across all processing steps will enhance reproducibility and facilitate future research comparing data processing choices.
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