Exercise in warm water is highly recommended for arthritis. The warmth and buoyancy of the water is soothing and makes it possible to move more easily and through a greater range of motion.
The warmth may also increase blood flow in general. This helps cleanse the joints and helps muscles relax. The increased hydrostatic pressure has numerous positive effects on the nervous system, cardiovascular system, and musculoskeletal system.
Many people report improved health from a regular aquatic exercise program. They feel more rested, have less joint pain, and benefit from improved strength and coordination.
However, studies don't always support these subjective reports. In a recent review of published literature from 1980 to 2006, aquatic exercise did not reduce pain more than land exercise. It was, however, better than no exercise program at all.
More studies are needed to identify who can benefit the most from aquatic therapy. There are many factors that need to be studied. Pain relief is only one measure of results. Other outcome measures include fitness, joint range-of-motion, muscle strength, endurance, and flexibility.