Knee friendly exercises for legs: a home workout that builds strength

The most knee-friendly leg exercises work your hips hard and bend your knees only as far as they're comfortable: glute bridges, hip hinges, step-ups onto a low step, sit-to-stands from a high seat, wall sits, straight leg raises, side leg raises and calf raises. Done slowly, two or three times a week, they strengthen the muscles that take load off the knee joint.

The rule that makes any of them safe is simple: a little discomfort that settles is fine, pain that's worse two hours later means you did too much. Below: what makes a leg exercise kind to knees, ten moves with sets and an easier and harder version of each, a 20-minute workout, a 6-week plan, the moves to change, and when to get your knee checked.

Why leg strength matters for sore knees

Your knee sits between two long levers, the thigh and the shin, and the muscles around it decide how much of every step, stair and squat the joint itself has to absorb. The front thigh (quadriceps) controls the knee as it bends under load, like going downstairs. The buttock and outer hip muscles keep the knee from collapsing inward. The hamstrings and calves steady it from behind.

That's why exercise is a first-line treatment, not an afterthought. The 2019 American College of Rheumatology and Arthritis Foundation guideline strongly recommends exercise for people with knee osteoarthritis, and the American Academy of Orthopaedic Surgeons publishes a home knee conditioning programme built on many of the same moves below. Avoiding leg work altogether tends to leave the muscles weaker and the knee less supported.

See someone first if your knee does this

Strengthening is for knees that are stiff, achy or complain on stairs. Get a doctor or physical therapist to look at it before you start if:

• It swelled up quickly after a twist, fall or pop.
• It locks, catches, or gives way under you.
• You can't put weight on it, or can't straighten or bend it fully.
• It's red and hot, or you have a fever.
• The pain wakes you at night, or has been getting worse for weeks despite rest.
• You've had knee surgery and haven't been cleared for exercise.

What makes a leg exercise knee friendly

No exercise is good or bad for every knee. What changes how much a move asks of the joint comes down to four things you can adjust:

• Depth. Research on squats shows the forces on the knee rise as the knee bends further. Stopping higher (sitting to a tall chair instead of a low one) is the easiest way to make a move gentler.
• Load. Body weight first. Add weight only when a move is comfortable for 12 slow reps.
• Speed and impact. Lowering slowly, over about three seconds, is easier on a joint than dropping. Jumps and fast landings ask the most.
• Where the work goes. Hip-led moves (bridges, hinges) load your buttocks and hamstrings with little knee bend. Knee-led moves (squats, step-ups) load your thighs. A knee-friendly plan uses lots of the first and a comfortable range of the second.

About "never let your knees go past your toes": in a squat, the knees moving forward is normal. One study of barbell squats found that stopping the knees from moving forward cut stress on the knee but sharply raised it on the hips and lower back. If forward knees hurt, sit back more or stop higher; if they don't, you don't need to force them back.

The knee pain rule to use during every workout

Many people with sore knees are told "if it hurts, stop", then stop everything. A more useful approach:

Then check later. The Arthritis Foundation's 2-hour rule: if your joint hurts more two hours after exercise than before you started, do less next time. Some soreness in the muscles the next day or two is normal and fades.

10 knee friendly leg exercises

1. Glute bridge

Lie on your back, knees bent, feet flat and hip-width apart. Squeeze your buttocks, then lift your hips until there's a straight line from shoulders to knees. Pause a breath, lower over three seconds. 2 to 3 sets of 10 to 15.

• Easier: a smaller lift.
• Harder: a 3-second hold at the top, a weight on your hips, then one leg at a time.
• Knee note: if the front of your knees aches, walk your feet a little further away.

2. Hip hinge, then Romanian deadlift

Stand tall, knees soft. Push your hips straight back, letting your chest tip forward with a flat back, until you feel a stretch down the back of your thighs. Squeeze your buttocks to stand up. Start with hands on hips; later hold a bottle or dumbbell in each hand close to your legs. 2 to 3 sets of 8 to 12.

• Easier: a shorter reach, with your backside touching a wall behind you as a guide.
• Harder: heavier weights, or a slow single-leg version holding a chair.
• Back note: keep the movement at the hips. If your lower back takes over, shorten the range.

3. Straight leg raise

Lie on your back, one knee bent, the other leg straight. Tighten the front of the straight leg's thigh, then lift it to the height of the bent knee. Lower slowly. 2 to 3 sets of 10 to 15 each leg. This one is in most knee rehab programmes because it trains the front thigh with no bend at all.

• Harder: a 3-second hold at the top, then a light ankle weight.

4. Sit-to-stand to a high seat

Sit on a chair with a cushion or two on it. Feet flat, slightly behind your knees. Lean forward and stand up, then sit back down slowly and lightly. 2 to 3 sets of 8 to 12.

• Easier: higher seat, hands pushing on your thighs.
• Harder: remove a cushion every week or two as long as your knee is happy, then hold a weight at your chest.
• Knee note: keep knees in line with your second toe; don't let them drift inward.

5. Wall sit, short depth

Lean your back against a wall, feet about a foot and a half forward. Slide down only until your thighs are working and your knees feel fine, maybe a quarter of the way. Hold. 3 to 4 holds of 15 to 30 seconds. Holding still (an isometric) lets you work the front thigh hard with no movement in the joint, and many people with sore knees find holds more comfortable than reps.

• Harder: longer holds, then a little lower.

6. Step-up onto a low step

Stand facing the bottom stair, holding the banister. Put your whole foot on the step and press through that heel to stand up on it. Step down slowly with the other foot. Do all reps on one side, then switch. 2 sets of 8 to 10 each leg.

• Easier: a lower step, such as a thick book or an exercise step.
• Harder: a slower step-down, then a bottle in each hand.
• Knee note: stepping down is often harder on sore knees than stepping up. If it is, take the slow lowering out for now.

7. Side-lying leg raise

Lie on your side, bottom knee bent for balance, top leg straight and slightly behind you, toes pointing forward. Lift the top leg about a foot and lower slowly. 2 to 3 sets of 10 to 15 each side. The outer hip muscles keep your knee from caving inward on stairs and when you stand on one leg.

• Harder: a loop band above your knees, or standing side steps with the band.

8. Standing hamstring curl

Hold the back of a chair. Keeping your thighs in line, bend one knee to bring your heel toward your buttock, then lower slowly. 2 sets of 10 to 15 each leg.

• Harder: an ankle weight or a band looped round the chair leg.

9. Calf raise

Stand with hands on a wall or counter. Rise onto the balls of your feet as high as you can, pause, lower over three seconds. 2 to 3 sets of 12 to 20.

• Harder: on the edge of a stair so your heels drop below the step, then one leg at a time.

10. Supported split squat, short range

Stand side-on to a chair and hold it. Step one foot back, back heel lifted. Lower straight down a few inches by bending both knees, then push back up through the front foot. Unlike a walking lunge, your feet stay put, which most knees find easier. 2 sets of 6 to 10 each leg.

• Easier: a smaller drop.
• Harder: deeper, as your knee allows, then holding a weight.

A 20-minute knee friendly leg workout

Do it two or three times a week, with a day between. Rest 45 to 60 seconds between sets.

Only have 15 minutes? Our 15 minute workout for women over 40 has three low-impact full-body circuits with a knee swap for every leg move.

Leave two or three reps in reserve on every set: you should finish feeling you could do a little more. It's the same effort rule we use in our beginner strength plan for women over 40, which adds the upper body and core to these leg moves.

A 6-week plan

Change one thing at a time. If your knee grumbles for more than a day after a change, go back a step for a week. If you'd like this worked out for you, our free 2-minute quiz asks about your knees, back and time, then builds a 12-week home plan with the knee swaps already chosen. Or read how our home strength plan for women over 40 works and what it costs first.

Leg exercises to change, not necessarily drop

These moves aren't harmful in themselves, but they ask the most of a sore knee. Change them before you cut them:

Mistakes that keep knees sore

• Doing nothing. Rest for a flare-up is fine; weeks of no leg work leaves the knee with less support.
• Only training the front of the thigh. Bridges, hinges and side raises matter as much.
• Letting knees cave in. Watch in a mirror: knees should track over the second toe.
• Dropping into the bottom. Lower slowly; the controlled part is the useful part.
• Adding everything at once. New move, more weight and more sessions in the same week is how flares start.
• Judging the session only during it. Check two hours later and the next morning.

Questions people ask

Are squats bad for your knees?

Not for most people. Squats to a comfortable depth are part of most knee programmes; it's very deep, heavy or fast squats that sore knees often don't tolerate. Start with sit-to-stands to a high seat and go lower only as your knee allows. Our guide to squat alternatives for bad knees puts nine options in order from easiest to hardest, with a step-by-step route back to a full squat.

Should I exercise my legs if I have knee arthritis?

For most people, yes: exercise is strongly recommended in the US rheumatology guideline for knee osteoarthritis. Start with the gentlest versions, use the 2-hour rule, and ask your doctor or a physical therapist if you're unsure what's safe for your knee.

Can I build leg muscle without bending my knees much?

Yes. Bridges, hip hinges, straight leg raises, side raises, wall sits at a short depth and calf raises all build leg muscle with little or no deep knee bend.

How often should I do knee friendly leg exercises?

Two or three times a week, with a rest day between, is a common dose for strength. A few gentle moves such as leg raises can be done more often if your knee likes them.

Is walking good for bad knees?

For most people, yes. Walking is low-impact and part of most arthritis exercise advice. Pair it with the strength work here; it doesn't replace it.

When will my knees feel better?

There's no set date, and nobody can promise it. Strength takes weeks to build. Keep a note of how stairs and getting out of a chair feel each week; if pain is getting worse rather than better after a few weeks, get it checked.

More plain guides on getting stronger at home: all our home strength guides.

Sources: Kolasinski S. et al., 2019 American College of Rheumatology/Arthritis Foundation guideline for the management of osteoarthritis of the hand, hip and knee, Arthritis Care Res, 2020. American Academy of Orthopaedic Surgeons, OrthoInfo, Knee conditioning program. Arthritis Foundation, the 2-hour pain rule. Escamilla R., "Knee biomechanics of the dynamic squat exercise", Med Sci Sports Exerc, 2001. Fry A., Smith J., Schilling B., "Effect of knee position on hip and knee torques during the barbell squat", J Strength Cond Res, 2003. NIAMS (NIH), Knee problems. US Department of Health and Human Services, Physical Activity Guidelines for Americans, 2nd edition, 2018. This guide is about exercise and is not medical advice; if a physical therapist or doctor has given you a programme, follow theirs.