1. Yoga improves balance. People with arthritis often adopt subtly out-of-whack postures to protect injured joints, which can lead to more aches and pains and decreased strength in affected areas. (When my left knee is aching, I notice that my right hip often hurts worse than my knee by the end of the day.) Yoga promotes symmetry and proper alignment to avoid muscle imbalance.
2. Yoga increases flexibility. Inactivity can cause muscles to shorten and tighten, which may cause joints to become further misaligned. Increased flexibility can result in better range of motion in your joints.
3. Yoga strengthens muscles. It's understandable that many people avoid exercising when their joints hurt, but this unfortunately leads to decreased muscle strength, which in turn contributes to decreased joint motion and ultimately greater pain. Vicious cycle, eh? A gentle yoga practice can help you maintain and build muscle without adding undue stress to your joints.
4. Yoga helps keep joints healthy. Range of motion exercises help "feed" cartilage by squeezing out old, stale fluid and allowing the joint to soak-up fresh, nutrient-rich fluid. You can't rebuild or regrow damaged cartilage, but you can help slow further deterioration.
5. Yoga improves posture. Poor posture can lead to added stress on joints and muscles. A regular yoga practice helps you become more aware of your body positioning, and more mindful of maintaining proper posture.