5 fixes for achy joints Don't let joint pain move you to the sidelines. Consult our guide for staying in the game. Rheumatoid arthritis This is an autoimmune disorder in which your body attacks healthy joint tissue. "Rheumatoid arthritis tends to affect the small joints in your hands and feet first," says Dr. Joanne Jordan, director of the Thurston Arthritis Research Center at the University of North Carolina. Then other joints, like the shoulders and elbows, start to become painful. Prevent it: Research from South Korea shows that people who consume the most vitamin D are 24 percent less likely to develop rheumatoid arthritis than those who consume the least D. Osteoarthritis The condition can announce itself with swelling, but it usually starts with nagging pain that can progress from minor to severe, Dr. Jordan says. Prevent it: Warm up before you work out - an injury in your 20s can resurface as osteo arthritis pain in your 40s. And stay slim. Otherwise, Jordan explains, your joints have to work harder to carry your weight, and fat cells promote joint inflammation. (Bored with your workout? Try one of these 3 New Treadmill-Free Cardio Routines.) Gout Excess uric acid in your blood can form crystals around your joints. The result is joint inflammation and pain, most commonly felt in your big toe. The ache manifests as severe, sudden swelling, known as a flare. Prevent it: Drink less alcohol and lay off heavy animal fats. A diet rich in purines - chemicals found commonly in red meat and seafood - can raise your gout risk, says Jordan, since your body metabolizes these compounds and makes uric acid. See why gout is The Secret Cause of Workout Soreness. Tendinitis Tendons attach muscle to bone. With tendinitis, that tissue becomes inflamed and sore. The worst nagging pain is felt at night. You can blame wear and tear due to sports, hobbies, or your job, says Dr. Theodore Blaine, chief of shoulder and elbow surgery and a professor of rehabilitation at Yale school of medicine. Prevent it: Avoid trying to go from slug to stud too fast. "If you're looking to get more fit, you should gradually increase your exercise," Blaine says. Bursitis This is inflammation of your bursa - fluid-filled pouches that lie next to your tendons. The hallmark symptoms are swelling and pain, and the condition can be caused by either an acute injury or repetitive overuse. Prevent it: Follow the same rule for preventing tendinitis. And forget the idea of "playing through the pain" - if you feel soreness in a shoulder, knee, or elbow, stop. For more doctor-approved health fixes and injury-prevention tips, check out The Most Annoying Sports Maladies Ever - Cured!)