Exercises must be individualized to work the right muscles while avoiding overstressing affected joints. Muscle strength is especially important because strong muscles better support and protect joints. Several studies show that if you improve muscle strength, you decrease pain. Joints will probably hurt during exercise, but shouldn't still hurt several hours later. Overuse, injury and obesity are contributing factors in osteoarthritis, and researchers have implicated a faulty gene in the breakdown of cartilage.
Heredity plays a role in other forms of arthritis, too, increasing susceptibility in some people.
Potential genetic therapy approaches are still far off, however.