Aquatic high-intensity interval training (HIIT) may be similarly effective to land-based HIIT in improving exercise capacity in people with chronic conditions: a systematic review and meta-analysis

OBJECTIVE: To investigate the effect of aquatic high-intensity interval training (AHIIT) on exercise capacity in people with chronic conditions. DESIGN: Systematic review and meta-analysis. PARTICIPANTS: Adults (age ≥18 years) with any chronic conditions (long duration, continuing health problems). DATA SOURCES: The databases Medline, EMBASE, CINAHL, SPORTSDiscus, PEDro and The Cochrane Library were searched from inception to 11 August 2023. ELIGIBILITY CRITERIA: Randomised or non-randomised controlled trials of adults reporting one or more chronic conditions were included, comparing the effect of AHIIT with a non-exercising control group, land-based high-intensity interval training (LBHIIT) or aquatic moderate-intensity continuous training (AMICT). RESULTS: Eighteen trials with 868 participants with chronic musculoskeletal, respiratory, cardiovascular, metabolic or neurological conditions were included. Adherence to AHIIT was high, ranging from 84% to 100%. There was moderate certainty in evidence according to the Grading of Recommendations Assessment, Development and Evaluation system for a moderate beneficial effect on exercise capacity standardised mean differences (SMD) 0.78 (95% CI 0.48 to 1.08), p<0.00001) of AHIIT compared with a non-exercising control group. There was moderate certainty in evidence for no difference of effects on exercise capacity (SMD 0.28 (95% CI −0.04 to 0.60), p=0.08) of AHIIT compared with LBHIIT. There was moderate certainty in evidence for small effect on exercise capacity (SMD 0.45 (95% CI 0.10 to 0.80), p=0.01) of AHIIT compared with AMICT. CONCLUSION: There are beneficial effects of AHIIT on exercise capacity in people with a range of chronic conditions. AHIIT has similar effects on exercise capacity as LBHIIT and may represent an alternative for people unable to perform LBHIIT. PROSPERO REGISTRATION NUMBER: CRD42022289001.