Cardiorespiratory Parameters Comparison Between Incremental Protocols Performed in Aquatic and Land Environments by Healthy Individuals: A Systematic Review and Meta-Analysis

Background Physical properties of water cause physiological changes in the immersed human body compared with the land environment. Understanding the magnitude of cardiorespiratory alterations might ensure adequate intensity control during aquatic exercise programs. Objective We aimed to compare the oxygen uptake (VO2), heart rate (HR), and rating of perceived exertion (RPE) parameters during aquatic and land incremental tests. Methods Four databases (PubMed, LILACS, EMBASE, and SPORTDiscus) were searched in September 2020. Eligibility criteria included studies in a crossover design comparing aquatic and land incremental tests for healthy individuals with at least one of the following parameters: VO2 (maximal, VO2max; anaerobic threshold, VO2AT), HR (HRmax; HRAT), and RPE (RPEmax; RPEAT). The random-effects meta-analysis included mean difference and 95% confidence interval for VO2 and HR or standardized mean difference for RPE. The Joanna Briggs Institute Critical Appraisal tool was adapted to assess methodological quality. Results Twenty-eight studies were eligible and included in the meta-analysis. Aquatic protocols showed lower values compared with land for VO2max (- 7.07 mL.kg(-1).min(-1); - 8.43 to - 5.70; n = 502), VO2AT (- 6.19 mL.kg(-1).min(-1); - 7.66 to - 4.73; n = 145), HRmax (- 11.71 bpm; - 13.84 to - 9.58; n = 503), and HRAT (- 15.29 bpm; - 19.05 to - 11.53; n = 145). RPEmax (0.01; - 0.16 to 0.18; n = 299) and RPEAT (- 0.67; - 1.35 to 0.02; n = 55) values were similar between aquatic and land protocols. Conclusions Our study reinforces the specificity of the environment during incremental tests for prescribing exercises based on physiological parameters as VO2 and HR parameters presented lower values in aquatic protocols than land protocols. Conversely, RPE seems an interchangeable measure of exercise intensity, with similar values during the protocols in both environments. Substantial levels of heterogeneity were present for the VO2max and HRmax meta-analyses, and as such, results should be interpreted with attention. Protocol Registration This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42020212508).