Straight Leg Raise

The straight leg raise strengthens the big thigh muscle (quadriceps) without bending the knee. That makes it one of the first exercises physiotherapists give for painful knees, knee arthritis and early recovery after knee surgery. It can be done lying on a bed, which suits older adults who find it hard to get down to the floor.

Written by Dr. V. B. Rajendra Prasad, MPT, licensed in the US and UK.

1. Start: one knee bent, the other leg straight and thigh tightened
2. Lift to the height of the other knee, hold, then lower slowly

How to do it

  1. 1

    Lie on your back on a firm bed or a mat. Bend one knee and place that foot flat. Keep the other leg straight.

  2. 2

    Tighten the thigh muscle of the straight leg, so the back of the knee presses down and the kneecap pulls up slightly. Pull your toes towards you.

  3. 3

    Keeping the knee straight and the thigh tight, lift the leg until your heel is about level with the other knee.

  4. 4

    Hold for 3 to 5 seconds.

  5. 5

    Lower the leg slowly back down, then relax the thigh fully before the next repetition.

How many

Start with 8 to 10 repetitions on each leg, 2 sets, once or twice a day. Build up to 15 repetitions as it gets easier.

Common mistakes

Letting the knee bend as you lift. Tighten the thigh first, then lift. If the knee keeps bending, lift lower.

Lifting too high. Going higher than the other knee adds little and can strain the lower back.

Arching the lower back. Keeping the other knee bent helps the back stay flat.

Dropping the leg. Lowering slowly works the muscle as much as lifting.

Holding your breath. Breathe out as you lift.

Make it easier

If lifting is too hard, start with thigh tightening alone: lie with the leg straight, tighten the thigh to press the knee down, hold for 5 seconds, relax. When you can do 10 of these comfortably, try the lift.

Make it harder

Hold the leg up for longer, up to 10 seconds. Later, add a light ankle weight (half a kilo to one kilo). Your physiotherapist will move you on to standing exercises such as sit-to-stand and step-ups.

Who it helps

Knee osteoarthritis
Recovery after knee replacement
Pain around the kneecap
Weak thighs after illness or a hospital stay
Early rehab after knee injury or surgery (when your surgeon allows)

When to stop and check

Stop and check with your physiotherapist if you feel sharp pain in the knee, hip or lower back. After knee surgery, follow your surgeon's or physiotherapist's advice on when to start. If you cannot keep the knee straight while lifting, tell your physiotherapist, as it shows the thigh muscle needs specific work.

Not sure you are doing it right? A physiotherapist can watch you on a video call, correct your form and build a full programme around it.

Get my form checked

Frequently asked questions

Is the straight leg raise good for knee arthritis?
Yes. Strengthening the thigh muscles is one of the most effective treatments for knee osteoarthritis, and the straight leg raise does this without bending a painful knee. It is usually one of several exercises in a programme.
When can I start straight leg raises after knee replacement?
Many patients start within the first days after surgery, often in hospital, but it depends on your surgeon's protocol. Ask your physiotherapist before starting.
Why does my knee bend when I lift my leg?
This usually means the thigh muscle is not yet strong enough to hold the knee fully straight, which is common after knee surgery or with knee pain. Go back to thigh tightening, lift lower, and tell your physiotherapist.
How many straight leg raises should I do a day?
A common starting point is 2 sets of 8 to 10 on each leg, once or twice a day. Quality matters more than numbers. Your physiotherapist will adjust this to your condition.

Related

Online physiotherapy for knee painOnline physiotherapy after knee replacementKnee strengthening exercisesKnee pain self-check
Dr. Rajendra

Written by Dr. V. B. Rajendra Prasad, MPT. Licensed to practice in the US (NY state) and UK (HCPC).
20 years of clinical experience. About Dr. Rajendra