Effect of aquatic high-intensity interval training on exercise capacity in people with chronic conditions: a systematic review and meta-analysis
Question
Does aquatic HIIT improve exercise capacity in adults with chronic conditions compared with control, land-based HIIT, or aquatic moderate-intensity continuous training?
Summary
This review found that aquatic HIIT improved exercise capacity compared with non-exercise controls and had similar effects to land-based HIIT, with a small benefit over aquatic moderate continuous training. Adherence was generally high, but adverse-event reporting was sparse.
Methodology
- Adults with chronic musculoskeletal, respiratory, cardiovascular, metabolic, or neurological conditions
- 868 participants.
- Water-based interval exercise.
- Work intervals: Varied by trial; examples included 30-second all-out swimming, 2-minute intense bouts, 3-4-minute deep-water running intervals, and 4-minute rounds.
- Recovery: Varied by trial.
- Intensity: Defined by RPE >=14, HRmax >=77%, VO2 >64% VO2peak/max capacity, or study-defined HIIT with monitored intensity.
- Often 45-60 minutes.
- Often 2-3 sessions per week.
- 8-16 weeks in many trials; minimum 6 weeks.
- Systematic review and meta-analysis of randomized and nonrandomized clinical trials
- Exercise capacity, Adherence, and Adverse events were tracked.
Outcomes
Capacity vs control
Aquatic HIIT improved exercise capacity compared with non-exercise control.
10 RCTs; SMD 0.78, 95% CI 0.48 to 1.08, P < 0.00001, I2 = 52%, moderate certainty
Capacity vs LBHIIT
Aquatic HIIT did not significantly differ from land-based HIIT.
4 RCTs; SMD 0.28, 95% CI -0.04 to 0.60, P = 0.08, I2 = 0%, moderate certainty
Capacity vs AMICT
Aquatic HIIT produced a small benefit over aquatic moderate-intensity continuous training.
4 RCTs; SMD 0.45, 95% CI 0.10 to 0.80, P = 0.01, I2 = 0%, moderate certainty
Adherence
Reported aquatic HIIT adherence was high across trials that reported it.
12 trials reported adherence; AHIIT 84-100%, LBHIIT 85-100%
Safety
Adverse events were sparsely reported; reported events did not show a clear excess versus comparators.
4 trials reported adverse events; examples included asthmatic attacks of unclear group, medical consultations, muscle/joint pain, fatigue withdrawal, and two trials with no AEs
Insights
- Aquatic HIIT may be useful for chronic-condition populations who benefit from buoyancy or reduced joint load.
- Most protocols were supervised and group-based, limiting direct app-only translation.
- Sparse adverse-event reporting means safety claims should be cautious.
Limitations
- Heterogeneity in AHIIT versus control comparisons.
- Methodological concerns and limited blinding.
- Adverse-event reporting was sparse.
- Follow-up periods were limited.
- Functional and quality-of-life persistence was not fully explored.
Safety
- Only 4 trials reported adverse events.
- Reported events included asthmatic attacks, knee pain/dyspnoea consultations, muscle/joint pain, one fatigue withdrawal in control, and two trials with no adverse events.