by Maura Daly Iversen, PT, DPT, MPH, ScD, and Anne-Marie Dupre, PT, DPT, MS, NCS
Your hips play an important role in many everyday activities, from sitting down to standing up, from walking to climbing stairs, from tying your shoelaces to cutting your toenails. If you have osteoarthritis (OA) of the hip, you know that pain and stiffness can make these activities difficult to do. You may avoid exercise because you think it will make things worse, but research shows that the right kind of exercise can actually help improve hip mobility and reduce pain. In this article, we’ll show you some easy stretching and strengthening exercises designed to do this. Many of the exercises are suitable for people who’ve had a hip replacement, but others may need modifying because they involve moves that can destabilize the new joint. The exercise instructions explain which ones these are.
To understand why the hip plays such a significant role in function, it is important to understand the design of the joint and how it moves. The hip is a ball-and-socket joint connecting the femur, or thighbone, and the pelvis. The head of the femur is the “ball,” and the part of the pelvis called the acetabulum is the “socket” (see The Hip Joint). Covering the ball and lining the socket is a slippery material called cartilage, which cushions the bone and allows the ball and socket to slide smoothly against each other when they move, instead of grinding. The ball-and-socket design allows the hip to have a great range of motion: You can bend at the hip and straighten up again; you can rotate your hip to the side; and you can rotate your legs, move them from side to side, and move them back and forth. None of this would be possible, of course, without the muscles surrounding the joint, which contract to make it move. The muscles also help keep the joint stable.
The muscles also play another important role. The hip is a weight-bearing joint: It helps support your body weight and absorbs some of the impact of activity. Your hip withstands forces equal to one-third of your body weight when you stand, three times your body weight when you walk up stairs, and more than four times your body weight when you run. When the cartilage is healthy, the muscles are strong, and the joint is stable, those forces are distributed equally across the joint, with the muscles and cartilage absorbing much of the stress.
In OA, the cartilage in the hip gradually wears away. As the cartilage wears, the space between the ball and socket narrows, and eventually bone rubs on bone. The joint begins to feel stiff and painful. The muscles around the joint are weak, mostly because people with OA tend to use their painful joint less (although a 1997 study suggested that muscle weakness might possibly be a risk factor for knee OA, rather than a result of it). Whatever the case, when muscles are weak, they can’t support the joint as well, and the added stress on the joint can accelerate cartilage degeneration. With weak muscles, your ability to move the joint decreases, too. Sometimes, when the joint isn’t moved much, muscles develop contractures, that is, they shrink, or shorten. Contractures alter the alignment of the joint and limit movement. They can also affect how the muscles work, so that more energy is required to carry out activities, resulting in fatigue.
As we noted earlier, hip OA can interfere with everyday activities such as walking. Limited hip mobility may impair personal hygiene and sexual function, too. It can also affect how you move your spine, knees, and ankles, putting abnormal stresses on these joints. For all of these reasons, it is important to maintain or improve your joint mobility with exercise.
A comprehensive exercise program contains three elements: flexibility, strengthening, and aerobic exercises. Flexibility exercises stretch the muscles around the joint and help to improve mobility. Strengthening exercises strengthen the muscles so that they better support and protect the joint. And aerobic exercise increases endurance and makes the muscles work more efficiently, improving function. Because the different types of exercise help you in different ways, you need all three in your program.
Last Reviewed on October 10, 2012
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