Exercise for Knee Arthritis
Exercise is the only treatment strongly recommended for everyone with knee osteoarthritis in the Australian guideline. What kind, how much, why it does not wear the joint out, and what to do when it hurts at first.
If you read only one page in this section, this is the one.
Exercise is the only treatment the Australian guideline strongly recommends for every single person with knee osteoarthritis. Not some people, not as an adjunct — everyone. No injection, tablet or supplement carries a recommendation of that strength.
It is also the treatment people are most likely to dismiss, partly because it is free and partly because it sounds like being told to try harder.
Why it works on a worn joint
The intuition that exercise must wear an arthritic knee out faster is understandable and wrong.
Cartilage has no blood supply. It is fed by the movement of joint fluid across its surface, which happens when the joint is loaded and moved. A joint that is rested is a joint whose cartilage is being poorly nourished.
Meanwhile the muscles around the knee — the quadriceps especially — act as shock absorbers. They take load that would otherwise pass through the joint surface. Quadriceps weaken measurably within weeks of reduced activity, and a weak quadriceps means more load reaching the arthritic surface with every step. This is the mechanism by which resting a sore knee makes it a more painful knee.
So the sequence people fall into — knee hurts, move less, muscle weakens, knee hurts more, move even less — is a real one, and it is reversible from any point on it.
What actually to do
The guideline names three things specifically: walking, muscle-strengthening exercise, and Tai Chi.
Strengthening is the part with the most direct evidence, and the quadriceps is the priority. Straight-leg raises, sit-to-stand from a chair, wall sits and step-ups all work. So does a leg press or a resistance band. The knee does not need to bend deeply for this to help.
Hip strength matters more than most people expect. The hip abductors control how the thigh tracks over the knee, and weakness there changes how load distributes across the joint. Side-lying leg raises and lateral band walks are unglamorous and useful.
Aerobic work — walking, cycling, swimming — maintains general fitness, helps with weight, and keeps the joint moving. Cycling is particularly useful when weight-bearing is painful, because it moves the knee through range with low load.
Range of movement. A knee that loses extension gets progressively harder to walk on. Simple work to keep the knee straightening fully is worth doing daily.
How hard, and how sore is too sore
The single most useful rule: soreness should settle within about 24 hours, and the knee should not be worse the next morning.
Some discomfort during and after exercise is expected and is not damage. What is not expected is sharp pain, a knee that swells noticeably afterwards, or pain that climbs session on session. Those mean the load is too high — reduce it, rather than stopping.
Most people err the other way. The commonest mistakes are doing too little to produce any adaptation, avoiding the loaded movements that would help most, and stopping at four weeks because nothing has changed yet.
How long it takes
Six to twelve weeks of consistent work before the difference is clear.
That is genuinely slow compared to a cortisone injection, which is why people give up on it and why injections feel more impressive. It is also why the benefit persists in a way an injection’s does not.
The trade-off is honest: the benefit lasts only as long as the exercise does. This is not a course of treatment you complete. It is closer to brushing your teeth.
Getting help with it
You can do this alone, and plenty of people do. But a few sessions with a physiotherapist or exercise physiologist at the start is worth it if you can manage it, mostly to get the intensity right and to be given permission to load a knee that hurts.
Ask your GP about a chronic disease management plan — where you are eligible, it provides a Medicare rebate for a number of allied health sessions each year.
What exercise cannot do
It will not regrow cartilage or reverse the arthritis. Nothing available does.
What it reliably does is reduce pain, improve function, and delay or remove the need for surgery in a great many people. It also materially improves how you recover if you do eventually have a knee replacement — the strength you take into that operation is a good predictor of how the first months afterwards go.
Which means the time spent on this is not wasted even in the scenario where surgery happens anyway.
Next: weight and knee load, the other strongly recommended treatment — or back to the overview.
Does exercise make knee arthritis worse?+
No, and this is the most common misconception about it. Cartilage is not a tyre tread that wears out faster the more you use it — it depends on loading and joint movement for its nutrition, because it has no blood supply of its own and relies on the movement of joint fluid. Muscle that supports the knee also weakens quickly without use, which increases the load the joint itself has to absorb. Sensible exercise protects an arthritic knee; avoiding movement reliably makes it stiffer, weaker and more painful.
What is the best exercise for knee arthritis?+
The Australian guideline strongly recommends land-based exercise for everyone with knee osteoarthritis, and specifically names walking, muscle-strengthening exercise and Tai Chi. Quadriceps strengthening has the most direct evidence behind it. Beyond that, the best exercise is largely the one you will actually keep doing — consistency matters more than the specific programme.
Should exercise hurt when I have knee arthritis?+
Some discomfort during and shortly after exercise is normal and not a sign of damage. A reasonable rule is that pain should settle within about 24 hours and should not be worse the following morning. Sharp pain, a knee that swells substantially afterwards, or pain that keeps climbing session to session means the load is too high — reduce it rather than stopping altogether.
How long before exercise helps my knee?+
Usually six to twelve weeks of consistent work before the change in pain and function is clear. This is slower than an injection, which is why people often abandon it, and it is also why the benefit lasts in a way an injection's does not. The catch is that the benefit continues only while the exercise does.
Do I need a physiotherapist or can I do it myself?+
Both work, but starting with a physiotherapist or exercise physiologist is worth it if you can. Most people under-load rather than over-load, avoid the specific movements that would help most, and stop too early. A few supervised sessions to establish the programme and the right intensity, then continuing independently, is a sensible pattern. A GP management plan may provide a Medicare rebate for a number of sessions each year — worth asking about.
Is swimming or cycling better than walking for knee arthritis?+
Water-based exercise and cycling are both useful, particularly when weight-bearing is very painful, and cycling is excellent for maintaining movement with low joint load. The guideline's strong recommendation is specifically for land-based exercise, which has the better evidence base for knee osteoarthritis. In practice a combination is often the most sustainable, and any of them beats none.