Advice guide
Knee Strengthening Exercises, and How to Do Them Well
Knees respond well to strength. Whether the problem is arthritis, kneecap pain, a settled injury or general weakness after a period of inactivity, building the muscles around the joint is one of the few interventions with broad support across a range of knee conditions. The exercises below are the ones used most often in general knee rehabilitation. They are ordered from gentle to demanding, so start where you can manage and progress deliberately. This is general information, and knee pain has several distinct causes, so persistent symptoms deserve a proper assessment.
Stage one, for a painful or swollen knee
When a knee is irritable, the aim is to keep the muscles switched on without provoking it. Small ranges, low load, high frequency.
| Exercise | How to do it | Dose |
|---|---|---|
| Quad set | Sitting with the leg straight, press the back of the knee down and tighten the thigh. | 10, hold 5 seconds, twice daily |
| Straight leg raise | Lying down, tighten the thigh and lift the straight leg about thirty centimetres. | 10, slow lowering |
| Heel slides | Lying down, slide the heel towards you, bending the knee within comfort, then straighten. | 10 to 15 |
| Inner range quads | Rolled towel under the knee, straighten the knee lifting only the lower leg. | 10, hold 3 seconds |
Stage two, building real strength
Once the knee tolerates stage one comfortably, move to weight bearing work. This is where the meaningful change usually happens, and it is also the stage people most often skip.
| Exercise | How to do it | Dose |
|---|---|---|
| Sit to stand | Stand up from a chair without using your hands, lowering slowly on the way down. | 10, 3 sets |
| Wall sit | Back against a wall, slide down to a comfortable angle and hold. | 20 to 45 seconds, 3 times |
| Step ups | Step up onto a low step leading with the affected leg, controlling the way down. | 10 each side, 2 to 3 sets |
| Split squat | One foot forward, one back, lower straight down keeping the front knee tracking over the foot. | 8 each side |
| Calf raises | Rise onto the toes and lower slowly, holding a support for balance. | 15, 3 sets |
Form points that protect the knee
Poor technique is the usual reason a sensible exercise irritates a knee. These points cover the majority of what we correct in clinic.
- Let the knee travel forward over the foot naturally, but do not let it collapse inwards towards the other leg
- Keep weight through the whole foot rather than rolling onto the inside edge
- Control the lowering phase, taking around three seconds, since that is where most of the strengthening happens
- Reduce depth rather than abandoning the exercise if pain increases
- Keep the hips level, particularly during step ups and split squats
How to progress sensibly
Change one thing at a time. Add repetitions first, then range or depth, then load such as a rucksack or dumbbells, and only then speed or impact. A useful general marker is the twenty four hour rule: if the knee is no worse the next morning, the dose was reasonable. If it is more swollen, stiffer or more painful the following day, step back to the previous level for a week. Progress is rarely linear, and a flare does not mean damage, though a sudden large increase in swelling should be assessed.
Knee pain during exercise, what it usually means
Not all knee pain during exercise is a problem. Distinguishing types helps you make sensible decisions, though when in doubt an assessment settles it faster than guesswork.
| Sensation | Usual interpretation | What to do |
|---|---|---|
| Familiar ache during, settles quickly | Acceptable working discomfort | Continue at current level |
| Ache worse the next morning | Dose too high | Reduce repetitions or depth for a week |
| Sharp catching pain | Technique or joint irritation | Stop that exercise and get it assessed |
| Giving way or locking | Mechanical problem | Stop and book an assessment |
| Rapid swelling after activity | Joint irritation or injury | Reduce load and seek assessment |
When to stop and seek help
Book an assessment if the knee gives way, locks or catches, if swelling appears rapidly, or if pain persists for several weeks despite consistent sensible work. Seek urgent medical care for a knee that is hot, red and very swollen alongside feeling unwell, for an obvious deformity, for an inability to bear weight after an injury, or for calf pain and swelling with breathlessness, which needs same day medical attention.
Common questions
Should I exercise a knee with arthritis?
Exercise is one of the core recommendations for knee osteoarthritis in UK guidance, alongside weight management where relevant. Load is adjusted to what the joint tolerates rather than avoided altogether.
Are squats bad for knees?
Not inherently. Squats within a comfortable range and with sensible technique are widely used in knee rehabilitation. Depth, load and speed are what need adjusting to the individual.
How long does it take to strengthen a knee?
Meaningful strength changes generally take a number of weeks of consistent work, but the timescale varies widely between individuals and we would not promise a figure for any specific case.
Should I use ice or heat?
Use whichever gives you more relief. Ice is often preferred for a freshly irritated or swollen knee, heat for general stiffness, and neither causes harm when used sensibly for short periods.
Can I run with knee pain?
Sometimes, with adjustments to volume, surface and pace, and sometimes not for a period. It depends heavily on the diagnosis, which is a good reason to have it assessed rather than deciding blind.
Do knee braces help?
Some people find a brace helpful for confidence during specific activities. It is a support rather than a solution, and it works best alongside strengthening rather than instead of it.