The best exercises for knee arthritis strengthen the THIGH and hip muscles, keep the knee bending and straightening fully, and raise your heart rate without pounding the joint. Do the strengthening two to three times a week.
Most people notice less pain and easier stairs after about 6 to 12 weeks of regular work. The first few weeks can feel like nothing is happening. That’s normal.
Exercise does NOT wear out an arthritic knee. A knee that’s rested too much gets weaker and stiffer, and usually hurts more.
Why exercise won’t wear out your knee
- Movement feeds cartilage: cartilage has no blood supply of its own. It takes in nutrients from the joint fluid as the knee is loaded and unloaded
- Strong muscles absorb load: the thigh muscles are the knee’s shock absorbers. Weak ones leave more of the load on the joint
- Ache isn’t damage: some pain during exercise doesn’t mean you’re harming the knee. How much an arthritic knee hurts is a poor guide to what’s happening inside it
- It’s a core treatment, not an extra: the NHS calls exercise one of the most important treatments for osteoarthritis, whatever your age or fitness
A knee you protect by resting gets weaker. A knee you load a little more each week gets stronger.
Phase 1: weeks 1 to 4, get it moving
Start here if your knee is sore or you haven’t exercised in a while. These are gentle enough to do most days. The numbers are starting points.
- Heel slides: lying on your back, slide your heel toward your bottom as far as is comfortable, then straighten the leg fully. Start with 10 to 15, slowly
- Thigh tightening (quad sets): sitting with the leg straight out, tighten the front of the thigh to press the back of the knee down, and hold for 5 seconds. Start with 10
- Straight leg raise: lying on your back with the other knee bent, tighten the thigh and lift the straight leg to the height of the other knee, then lower slowly. Start with 2 sets of 10
- Sit-to-stand from a high seat: stand up and sit down slowly, without pushing off with your arms if you can. Add a cushion to raise the seat if needed. Start with 2 sets of 8 to 10
- Bridge: lying on your back with knees bent, squeeze your buttocks and lift your hips, hold for 3 seconds. Start with 2 sets of 10
- Exercise bike: about 10 minutes at an easy pace, with the seat high enough that the knee is only slightly bent at the bottom of each turn
Phase 2: weeks 4 to 8, build strength
Strengthen two to three times a week with a rest day between. The last few reps of each set should feel like work.
- Lower sit-to-stands: use a normal chair height, then wear a backpack with some weight in it once that’s easy. Start with 3 sets of 10
- Step-ups: step up onto a low step with the sore leg, bring the other foot up, then step down slowly. Start with a 4 to 6 inch (10 to 15 cm) step, 2 to 3 sets of 10
- Mini squats: feet hip-width apart, bend the knees about a quarter of the way down as if sitting back into a chair, then stand tall. Start with 3 sets of 10
- Side-lying leg lifts: lie on your good side with the bottom knee bent, lift the top leg up and slightly back, then lower slowly. This strengthens the outer hip, which stops the knee dropping inward. Start with 3 sets of 10
- Ankle weights: add a light one to straight leg raises once the plain version is easy
Phase 3: week 8 onward, make it part of life
- Harder strength work: higher steps, deeper squats within comfort, sit-to-stands on one leg, or a leg press machine at the gym
- Balance: stand on the sore leg for 30 seconds next to a kitchen counter, then try it with your eyes closed
- Low-impact aerobic exercise: walking, cycling, swimming or water exercise. Build toward the general adult target of about 150 minutes a week, in any size chunks
- Keep going: two or three strength sessions a week to hold on to your gains. The benefit fades over a few months if you stop
The pain rules
- During exercise: a mild to moderate ache is fine, up to about 5 out of 10
- Afterward: it should settle within an hour or two
- The next-morning test: if the knee is more painful, stiffer or more swollen than usual the next morning, you did too much. Cut back the reps or weight for a few days, then build again
- After a flare: drop back to the Phase 1 exercises for a few days rather than stopping completely
How to progress
- Move up when you can do 3 sets of 10 to 15 with good control and the knee passes the next-morning test
- Change one thing at a time: reps first, then weight or step height, then how often
- Expect wobbles: a flare every few weeks is common and doesn’t mean the program isn’t working
What to stop or avoid
- Deep squats or lunges that pinch: work in the comfortable range and let it grow
- Big jumps in load: doubling your walking distance in a week is a common trigger for flares
- Kneeling on hard floors if it hurts. Use a thick cushion
- Anything that causes sharp pain, locking or the knee giving way
For the condition itself and the other treatments, see knee arthritis.
If you’ve given exercise a proper go for three months and the knee is still running your life, see when is it time for a knee replacement.
If a worn meniscus is part of the picture, see meniscus tear exercises.
Get seen urgently if
- The knee is suddenly hot, red and swollen, especially with a fever
- Your calf is swollen, warm or painful
- You can’t put weight on the leg after a fall or twist
Get it checked if
- The knee locks and won’t straighten, or keeps giving way
- Swelling keeps coming back after exercise despite cutting back
- Pain is keeping you awake most nights
- Nothing has changed after 12 weeks of regular, progressing exercise
An arthritic knee needs more strength, not more rest.