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.