Exercise may seem like the worst thing for stiff, aching joints. But it is just what most people with arthritis need. Completing an eight-week program designed for arthritis sufferers improved range of motion and reduced pain and fatigue, according to a study of 346 patients conducted by the Thurston Arthritis Research Center at the University of North Carolina at Chapel Hill.

Bonus: While swimming pool exercise frequently is recommended for people with arthritis, this study looked at routines that could be done while sitting or standing. Some classes included floor exercises.

Who was studied: The study, published this year, included people with arthritis severe enough to limit normal activities. The average participant's age was 70. "We were specifically evaluating the people with the least amount of activity coming in," says Leigh F. Callahan, an associate professor of medicine who led the study. Arthritis affects about 46 million Americans.

Which exercises worked: Participants did movements such as lifting their arms overhead or getting up and down from a chair. Workouts also incorporated stretching with resistance bands and light weight lifting. The routine is known as the Arthritis Foundation Exercise Program.

How long results lasted: Participants experienced improvements in pain and fatigue for at least six months after the class. Though not tracked beyond that, patients reported that they felt less confident in their ability to safely exercise as time passed, indicating that people may need to remain in a class to show continued benefit, Dr. Callahan says.