There are many different types of arthritis, which means “inflammation of a joint,” but the most common is osteoarthritis. Osteoarthritis makes your joints feel stiff and achy, and it results from wear and tear that causes the cartilage in the joints to break down. Without the cartilage, the bones in the joint rub together, causing pain and sometimes loss of movement.

There is no known single cause of, or cure for, osteoarthritis. Exercise, however, is one of the best things you can do to relieve the discomfort caused by arthritis and increase range of motion in joints. In fact, a motto of the Arthritis Foundation says it best: “Moving is the best medicine.” Yet by one estimate, 60 percent of adults who suffer from some form of arthritis are either completely sedentary or don’t exercise enough to reap any benefits from physical activity. Exercise — such as walking, swimming or water aerobics, riding a bicycle, and doing yoga — increases energy, boosts mood, and reduces pain, among other benefits. If you don’t exercise because you’re worried that the activity could worsen your discomfort, know that research shows the opposite: 30 minutes of moderate activity can ease symptoms of arthritis.

Morning stiffness is a hallmark of osteoarthritis. But you can’t stay in bed all day! Try these two stretches, recommended by the Arthritis Foundation, when you first wake up.

For the wrists and hands

Stand, or sit in a low-back chair. Hold your palms face out to the sides of your shoulders with your elbows about waist level, making a “W” shape. Keep your shoulders relaxed, not hunched. Bring your elbows back to pinch your shoulder blades together. Hold for three counts. Then relax, and repeat once or twice more.

For the back

Stand in front of a doorway with your feet shoulder-width apart and your knees slightly bent. With arms bent at the elbow in a 90-degree angle, place your palms on the sides or frame of the doorway. Lean forward, and you’ll feel your pectoral muscles stretch. Bonus: The muscles on the front of your shoulders get a stretch, too.

A 2009 study suggests that tai chi, a traditional Chinese form of exercise, relieves pain in people who suffer from osteoarthritis. Tai chi is a versatile activity that can be easily incorporated into your daily activities. To find a class near you, contact the Arthritis Foundation, Or purchase the organization’s DVD “Tai Chi for Arthritis” ($29.95). You don’t need any special clothing or equipment to practice tai chi — just an open mind.

Knees are the joint most commonly affected by osteoarthritis, but women who have strong quadriceps (thigh muscles) cut their risk of developing arthritis in the knees significantly, according to researchers at the Clinical Osteoarthritis Research Program at the University of Iowa. Quadriceps strength has long been known to be associated with better ability to walk and get up from a chair, but this particular study also indicates that quadriceps strength may protect against symptomatic knee osteoarthritis. Exercises such as lunges and squats are very effective for building thigh strength.