Fact sheet: Exercise, weight loss and osteoarthritis

Pain, stiffness, and crunching in the joints: these are the typical signs of osteoarthritis (OA). It happens to most people when they get older, and some are already having joint problems in middle age. If symptoms get worse, they can severely limit mobility. And osteoarthritis is the main reason that people get knee or hip replacements.

If you have painful osteoarthritis, it can be harder to get enough exercise and you may gain more weight. And if you gain more weight, it could make the OA worse, especially in the knees. But how much does it help to exercise and what exercise might be best for people with OA? And what about weight loss? Can that increase mobility? Researchers have found some answers to these questions that might be important for people with OA.

What causes the most stress on joints affected by osteoarthritis?

Our joints take a lot of wear and tear during our lives, and this becomes noticeable with age. The knees are the joints particularly affected. As we age or if we have had an injury in a joint, OA will often develop. If you have OA in a joint, it means that some parts of the joint have been damaged, especially the cartilage. The cartilage is a tough kind of tissue at the end of bones where they meet to form a joint. If the cartilage is damaged and bits of the cartilage break away, those bits can move into the joint space and irritate the muscles. This can cause pain and problems with movement in the joint. And when the cartilage is not able to work as it should, other parts of the joint and the muscles have to work harder to try and manage movement.

Cartilage itself is not sensitive to pain, but the muscles and other tissues in and around the joint are. If the cartilage wears away a lot, then the bones will rub directly against each other, causing more pain. Bone tissue can grow and form what are called spurs or osteophytes. This can severely disable movement in the joint.

Other than getting older, being very overweight (obese) is the biggest risk factor for OA developing or getting worse. There is a complex relationship between OA and being overweight. People are obese if they have a body mass index of more than 30.If a woman of 160 cm weighs 80 kg, her body mass index is 31.25, and she would be considered obese. Click here to find out more about the body mass index and how to calculate it.

Being very overweight puts a lot of strain on the joints, especially the knees. And it also often slows people down and makes it difficult for them to move. If overweight people also have OA, and they are stiff and in pain, they might get even less exercise and put on more weight.

On top of that, being more inactive makes your muscles less fit and other parts of the joints stiffer. When the muscles around the affected knee get weaker, it is another risk factor for OA getting worse. So while some people might think that exercise itself adds extra wear and tear to the joints, in fact being overweight and inactive is more of a stress, especially for the knees. It might not seem sensible to exercise a damaged joint, but when the damage is due to OA, it is actually necessary to keep the joint mobile and to keep your weight down.

How much relief from osteoarthritis can I expect if I lose weight?

If you have osteoarthritis and you are overweight or obese, your doctor will probably strongly encourage you to try to lose weight. That is easy to say, but much harder to do. Losing weight needs a lot of motivation, and you will probably have to change your diet as well as get more exercise. Researchers have shown though, that it is worth the effort. You can read more about that research here.

Experts often recommend that people who are overweight and have OA try to lose about 10% of their body weight. So if you are 80 kg, this means losing 8 kg. If you can manage to do that within 3 months, then you could expect to considerably increase your mobility. But even after losing 5% of your body weight within 5 months, you can expect to notice a difference. Losing weight has other health benefits too, and you can read more about them here.

What kinds of exercise could help?

There are many options for exercise when you have OA. There are specific exercise therapies for the particular joint too. These exercises are put together and explained by a physiotherapist, to help increase movement in a joint. Therapeutic exercises can involve muscle strengthening, flexibility or resistance workouts. But they can also include functional or coordination exercises such as certain stepping exercises or using a balance board). These therapeutic exercises can help in the short-term, but if you stop the therapy, the benefit you had will not last for long. You can expect more benefit from forms of exercise that you can integrate into your life and keep doing in the long term.

Many different kinds of exercises have been studied for people with OA, including brisk walking, aerobics, bike-riding and swimming. In general, these can help reduce the disability that OA causes. Tai chi has not yet been proven to help reduce the disability from osteoarthritis. Aquatic exercises or water aerobics can be less painful than other forms of exercise for people with OA in the knees. Water-based exercise can help relieve the pain and disability of OA in the short-term, but again, if you stop doing it, there will be no long-lasting benefit.

Brisk walking is a popular, low-cost and low-injury form of exercise. It is an easy way to stay more active and has a lot of benefits, if you can manage to keep doing it. You can read about the health benefits of walking and ways that can help you walk more in your everyday life here.

Exercise is not a cure-all for OA and it will not solve all the problems that this condition causes. But losing weight and incorporating exercise into your life can help stop your joints from getting worse, and help you live better with osteoarthritis. It might seem hard to keep active over the years, but it can considerably improve your quality of life.

© IQWiG (Institute for Quality and Efficiency in Health Care)