This summary of a Cochrane review presents what we know from research about the effect of aquatic exercise for osteoarthritis of the hip or knee. The review shows that:
There is gold level evidence that for osteoarthritis of the hip or knee, aquatic exercise probably slightly reduces pain and slightly improves function over 3 months.
The progression of damage in osteoarthritis as seen on x-rays was not measured. Therefore, it is not known whether aquatic exercise improves the progression of osteoarthritis.
Aquatic exercise may not cause harm. But there is not enough evidence to be certain.
More research is needed to determine long term effects and to understand which type of aquatic exercise, how often and for how long, might be beneficial.
What is osteoarthritis and what is aquatic exercise?
Osteoarthritis (OA) is the most common form of arthritis that affects the hips and knees. In OA, the cartilage that protects the ends of the bones breaks down and causes pain and swelling. Aquatic exercise is sometimes known as 'pool therapy' or 'hydrotherapy'. It involves exercises in water that is heated to about 32 to 36 degrees Celsius. Exercises may include aerobic activities, stretching and strengthening, and range of motion.
What are the effects of aquatic exercise?
In the studies, some people did aquatic exercises for different lengths of time and number of sessions per week, while other people did no exercise or exercises on land. The effects were mainly measured at 3 months.
In people with osteoarthritis of the hip or knee,
- pain may decrease by 1 more point on a scale of 0 to 20 with aquatic exercise
- function may improve by 3 more points on a scale of 0 to 68 with aquatic exercise
- progress of damage of osteoarthritis as seen on x-rays was not measured
- there may be little or no difference in harms such as pain or other symptoms with aquatic exercises than with no exercise