Aquatic exercise for knee and hip osteoarthritis: what the Cochrane evidence shows

For people with painful knee or hip osteoarthritis, land-based exercise can feel like a catch-22: the joints that need loading are the ones that hurt under load. Water changes that equation — buoyancy reduces joint compression while still allowing muscles to work against resistance.

This Cochrane review pooled 13 randomised controlled trials, 1,190 participants in total, comparing aquatic exercise programs against no-exercise controls in adults with knee and/or hip osteoarthritis. Immediately after a program, participants in aquatic exercise rated their pain and their disability roughly 5 points lower on a 0–100 scale than controls, and their quality of life about 7 points higher.

Those are modest numbers, and the authors are careful about them: the certainty of the evidence was moderate, the measurements were taken right after the programs ended, and it is less clear how long the benefit persists without continued activity. What is notable is the safety profile — across all included trials, no serious adverse events were attributed to aquatic exercise.

For a condition where fear of flare-ups keeps many people inactive, an intervention that reliably produces some benefit with essentially no serious risk earns its place — particularly as an entry point for people who cannot yet tolerate land-based programs.

Key findings

• 13 randomised trials with 1,190 participants with knee and/or hip osteoarthritis were included.
• Aquatic exercise improved pain and disability by about 5 points on a 0–100 scale versus control immediately after a program.
• Quality of life improved by about 7 points on a 0–100 scale.
• No serious side effects were reported in any included trial.
• Effect sizes were small-to-moderate and measured at the end of programs; long-term durability was less clear.

Clinical relevance

Aquatic sessions let clients with osteoarthritis start moving earlier and with far less joint load than land-based work, then act as a bridge toward it. This is exactly how our community and aquatic rehabilitation programming is used: begin in water where movement is tolerable, build capacity, and progress to land-based strengthening as confidence and tolerance grow.

Prepared by the Volt Health team as an educational summary of the cited publication. It is not medical advice; assessment and treatment decisions should always be made with a qualified health professional.