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Best leg exercises for knee-friendly strength: 7 moves and a sample week

Strong legs, knees that stay calm. You choose the depth. The load goes up slowly. The hips do their share.

By Susmit Jalan, coach at Online Fitness Worldwide.

Your knees grumble on the stairs. Or someone told you squats wreck knees. You still want strong legs. Good. Strong legs are the plan.

For knee osteoarthritis, a Cochrane review pooled 44 trials. Exercise cut pain by about 12 points on a 0 to 100 scale, and improved function by about 10.[4] NICE in the UK calls therapeutic exercise a core treatment, and names local muscle strengthening.[3]

For pain around the kneecap (patellofemoral pain), an international expert consensus backs exercise therapy, especially hip and knee exercises together.[5]

WHO advises muscle-strengthening work for all the major muscle groups on 2 or more days a week.[1] Legs included. This list keeps it knee-friendly: you set the depth, the load climbs slowly, and the hips work as hard as the knees.

This is training, not treatment. Knee swollen, locking or giving way? Read "Before you start" first.

See also: Best strength exercises for runners: 7 moves and a sample week · Best strength exercises for over 60s: 7 moves and a sample week

The 7 best leg exercises for knee-friendly strength

  1. Box squat

    Why
    You choose the depth, and every rep stops at the same place. In the squat, knee forces rise as the knee bends further. They are lowest in the top half.[7] That is a general pattern. People respond differently, so choose your depth by comfort and control, not by a force chart.
    How
    Stand in front of a sturdy chair or box, feet hip-width or a little wider. Arms forward, or hold a weight at your chest. Sit back and down until you just touch the seat. Don't flop. Stand up. Knees point the same way as your toes. Too much? Add a cushion and sit higher.
    Dose
    2 to 3 sets of 8 to 12. Lower the seat a little when 12 feels easy and calm. If knee ache the next day rises and stays up for 24 hours, raise the box again.

  2. Step-up

    Why
    Stairs, kerbs, a hill. One leg at a time, at a height you pick.
    How
    Start low: the bottom stair at home is fine. Whole foot on the step. Push through it and stand tall. Lower the other foot slowly, don't drop. Hold the rail or a wall. Go higher only when it stays comfortable. Don't raise the step in the same week you add load.
    Dose
    2 to 3 sets of 8 to 10 each leg.

  3. Romanian deadlift

    Why
    Hamstrings and glutes do the work. Your knees stay softly bent and barely move. A good leg move on a day the knees feel grumpy.
    How
    Feet hip-width, knees soft. Hold a dumbbell or a backpack. Push your hips back and let the weight slide down your thighs. Back long. Stop when you feel the stretch at the back of your legs. Stand up by squeezing your glutes.
    Dose
    2 to 3 sets of 8 to 12.[9]

  4. Glute bridge

    Why
    Hip strength from the floor. For pain around the kneecap, a review found hip work plus thigh work cut pain and improved function, with some evidence it helped more at 1 year than thigh work alone.[6]
    How
    Lie on your back, knees bent, feet flat. Press through your heels and lift your hips until knees, hips and shoulders line up. Squeeze. Lower slowly. Easy? Do it on one leg, or with a weight on your hips. Move to one leg only while the two-leg version stays pain-free, and check how the knee feels the next day.
    Dose
    2 to 3 sets of 10 to 15.

  5. Side-lying leg raise

    Why
    Trains the side of your hip, the muscles that keep your pelvis level when you stand on one leg. Hip-focused work is half of what the consensus backs.[5]
    How
    Lie on your side, bottom knee bent. Top leg straight, in line with your body, toes pointing forward. Lift the top leg about a hand's height. Lower slowly. Don't roll back. Easy? Add a band above the knees.
    Dose
    2 to 3 sets of 12 to 15 each side.

  6. Split squat

    Why
    Single-leg strength with both feet on the floor. No jump, no step. You set the depth.
    How
    One foot forward, one back, like a long stride. Hold a wall or a chair. Lower your back knee towards the floor, only as far as stays comfortable. Front knee over the middle of your foot. Push through the front foot to come up. All reps one side, then the other. For the first 2 weeks, the wall or chair support is not optional.
    Dose
    2 sets of 8 to 10 each leg.

  7. Seated knee extension

    Why
    The thigh muscles (quadriceps) on their own. Knee-focused work is the other half of what the consensus backs.[5] No machine needed.
    How
    Sit tall on a chair. Ankle weight, or a band looped round the chair leg and your ankle. Straighten your knee as far as stays calm; full lockout isn't required every rep. If straightening irritates, start in the middle of the range or with a lighter band. Hold for 2 seconds only while pain stays mild and settles within the session. Lower for 3. No weight yet? Your leg is enough.
    Dose
    2 to 3 sets of 10 to 15 each leg.

How deep, how hard, how often

Depth is a dial, not a rule. Knee forces in the squat climb as you bend and peak near the bottom. The same review found the parallel squat, thighs level with the floor, was not injurious to a healthy knee.[7]

Deep squats? The reviews differ. One favoured parallel over deep for healthy knees.[7] Another concluded that, with technique learned under expert supervision and loads built up slowly, deep squats did not add injury risk. It also warned that very heavy half and quarter squats are not the safe option they look like.[8] So: earn your depth. Go as low as stays smooth and calm.

Pair hip and knee. For pain around the kneecap, the 2018 consensus backs exercise therapy, especially hip-focused and knee-focused exercises combined.[5] Items 4 and 5 are hip. Items 1, 2, 6 and 7 are knee. Item 3 is mostly hip.

Told you have knee osteoarthritis? NICE advises explaining that joint pain may increase when you start exercise, and that regular, consistent exercise will still benefit the joints.[3] Ask your doctor or physio how much is fine for you.

Keep going. In the Cochrane review, the drop in pain was still there 2 to 6 months after formal programmes ended. Programmes delivered one-to-one tended to do better than classes or home programmes, though the studies varied a lot.[4]

Twice a week covers the WHO minimum.[1] When you beat 12 good reps by 1 or 2, add a little: 2 to 10% more load.[9] No heavier weight? Lower more slowly, lower the box a little, or add a set.

A sample week for knee-friendly leg strength

Sample only. Not a prescription. Adjust it to your body, your health and your history.

  • Monday, about 30 minutes: box squat, Romanian deadlift, glute bridge, side-lying leg raise. 2 to 3 sets each.
  • Tuesday: an easy walk or cycle.
  • Wednesday: rest, or a walk.
  • Thursday, about 30 minutes: step-up, split squat, seated knee extension, glute bridge. 2 to 3 sets each.
  • Friday: rest.
  • Saturday: something you enjoy. A walk, a swim, a ride.
  • Sunday: rest.
  • Knees grumpy the next day? Keep the session, shrink it: higher seat, lower step, less load.
  • Pain check: mild discomfort that settles soon is fine. Pain that rises during a set means make it easier: less range or less load. Sharp pain, swelling, pain spreading down a limb, numbness, a joint giving way or locking means stop and get it checked. I'm a coach, not a physio or doctor.

Want it coached live?

Iron Hour is 60 minutes, 1:1. Set-up at minute 0: camera placed so I can see your feet, knees and hips. Warm-up from minute 4. The primary lift at 14, at the depth we agreed. Accessories at 28. Cool-down at 50.

Return is 45 minutes, 1:1, 12 alternate-day sessions a month. For when a sore knee, a break or life put training on hold. We build the base first.

Lean Reset is 20 sessions a month, 1:1. Open Floor is a small group. I'm a coach, not a physio: if your doctor or physio has set limits, we train inside them.

Coached live on Google Meet, Zoom or FaceTime, in your own living room. In Hindi or English. On IST. Not sure yet? Start with a 30-minute consultation. It is a conversation, not training. Booking holds a time. The fee is agreed directly.

See the programsAsk on WhatsApp (opens in a new tab)

Before you start

General information, not medical advice. ACSM's screening model says: if you are inactive, have no symptoms and no known heart, metabolic or kidney disease, you can start light to moderate exercise without medical clearance and build up gradually. If you have one of those conditions, or symptoms, get medical clearance first.[10] The NHS says to see a GP if knee pain does not improve within a few weeks. It says to get urgent advice if your knee is very painful, you cannot move it or put weight on it, it is badly swollen or has changed shape, it locks, gives way or painfully clicks, or you have a very high temperature with redness or heat around the knee. Painless clicking is normal.[2] Outside the UK, that means your doctor or local urgent care. Recent knee injury or surgery? Follow your surgeon's or physio's plan first. Train on a floor that doesn't slip. Stop if you get sharp pain, chest pain or dizziness.

ASCA Level 1 (strength and conditioning) and ACE (anatomy and biomechanics). These are credentials held by the coach. Neither body endorses this business or this article.

Sources

  1. [1] World Health Organization. WHO guidelines on physical activity and sedentary behaviour. Geneva: WHO; 2020. https://www.who.int/publications/i/item/9789240015128 (opens in a new tab)
  2. [2] NHS. Knee pain. nhs.uk. https://www.nhs.uk/conditions/knee-pain/ (opens in a new tab)
  3. [3] National Institute for Health and Care Excellence (NICE). Osteoarthritis in over 16s: diagnosis and management. NICE guideline NG226. 2022. https://www.nice.org.uk/guidance/ng226/chapter/Recommendations (opens in a new tab)
  4. [4] Fransen M, McConnell S, Harmer AR, Van der Esch M, Simic M, Bennell KL. Exercise for osteoarthritis of the knee. Cochrane Database Syst Rev. 2015;(1):CD004376. https://doi.org/10.1002/14651858.CD004376.pub3 (opens in a new tab)
  5. [5] Collins NJ, Barton CJ, van Middelkoop M, et al. 2018 Consensus statement on exercise therapy and physical interventions (orthoses, taping and manual therapy) to treat patellofemoral pain. Br J Sports Med. 2018;52(18):1170–1178. https://doi.org/10.1136/bjsports-2018-099397 (opens in a new tab)
  6. [6] Lack S, Barton C, Sohan O, Crossley K, Morrissey D. Proximal muscle rehabilitation is effective for patellofemoral pain: a systematic review with meta-analysis. Br J Sports Med. 2015;49(21):1365–1376. https://doi.org/10.1136/bjsports-2015-094723 (opens in a new tab)
  7. [7] Escamilla RF. Knee biomechanics of the dynamic squat exercise. Med Sci Sports Exerc. 2001;33(1):127–141. https://doi.org/10.1097/00005768-200101000-00020 (opens in a new tab)
  8. [8] Hartmann H, Wirth K, Klusemann M. Analysis of the load on the knee joint and vertebral column with changes in squatting depth and weight load. Sports Med. 2013;43(10):993–1008. https://doi.org/10.1007/s40279-013-0073-6 (opens in a new tab)
  9. [9] American College of Sports Medicine. Position stand: Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687–708. https://doi.org/10.1249/MSS.0b013e3181915670 (opens in a new tab)
  10. [10] Riebe D, Franklin BA, Thompson PD, et al. Updating ACSM's recommendations for exercise preparticipation health screening. Med Sci Sports Exerc. 2015;47(11):2473–2479. https://doi.org/10.1249/MSS.0000000000000664 (opens in a new tab)