Oct. 18 (HealthDay News) -- Doing stretching and aerobic workouts in warm water may help relieve pain and improve daily function in people with knee or hip osteoarthritis.

That finding was offered by Danish researchers who reviewed six studies involving about 800 patients.

In the studies, participants did aquatic exercise for different lengths of time and numbers of sessions per week. In most of the studies, patient progress was assessed after three months of therapy.

"In people with osteoarthritis of the hip or knee, pain may decrease by one more point on a scale of 0 to 20 with aquatic exercise, and function may improve by three more points on a scale of 0 to 68," the review authors wrote.

"There is gold-level evidence that for osteoarthritis of the hip or knee, aquatic exercise probably reduces pain and slightly improves function over three months," they noted. "Based on this, one may consider using aquatic exercise as the first part of a longer exercise program for osteoarthritis patients."

The review authors weren't able to find evidence that patients experienced any changes in walking ability or stiffness after aquatic exercise sessions. They said more research is needed to determine whether aquatic exercise offers any long-term benefits for osteoarthritis patients, and the types, duration and frequency of aquatic exercise that may be most effective.

The review is published in the current issue of The Cochrane Library journal.

Osteoarthritis, the most common form of arthritis, affects about 21 million Americans, according to the Arthritis Foundation. Treatment typically involves a combination of weight control, medication, physical therapy and exercise.

SOURCE: Center for the Advancement of Health, news release, Oct. 16, 2007