A single leg wall sit is a wall sit where you hold the bottom position on one leg. You lean back on a large exercise ball against a wall, slide down until your knees are bent to about a right angle, then lift one foot just off the floor and hold. The standing leg takes all of your weight, and you will feel the front of that thigh and the buttock working hard. Physios usually add it only once a wall sit on both legs feels easy.

How to do the single leg wall sit with a ball

Put a large exercise ball against a wall and lean back into it, so it sits behind the lower half of your back. Stand with your feet hip width apart, toes forward, far enough from the wall that your knees will stay above your ankles when you sit down.
Hold your hands together at chest height, arms forward, as the woman in the video does. Bend your knees slowly, with the ball rolling along with you, until your knees reach about a right angle, or stop higher if that depth hurts.
Check that each kneecap lines up with your second toe and sits above the ankle, not out past your toes. Keep the natural small curve in your lower back against the ball.
Lift one foot a little off the floor and hold, keeping the standing knee steady with no wobble in or out. Breathe steadily throughout.
Put the foot back down, then press through both feet to slide back up to standing. Lift the other foot on the next rep, so both legs get the same work.

What you should feel

A strong effort that builds in the front of the thigh and the buttock of the standing leg. The kneecap itself should not hurt.

Common mistakes

Having your feet so near the wall that the standing knee ends up in front of your toes.
Shifting or tipping sideways as the foot comes up.
Letting the standing knee cave inward.
Holding your breath while the foot is off the floor.

How often

Try 3 to 5 single leg holds on each side, starting at about 5 to 10 seconds and working toward 20 to 30. A higher position, with less knee bend, makes it easier. Your physio will adjust this.

Stop and check with your physio if

Sharp pain in or behind the kneecap, or knee pain that builds from one hold to the next.
The standing knee buckles, or you cannot slide back up under control.
Chest pain or pressure, dizziness or feeling faint, a racing or irregular heartbeat, or being far more out of breath than the effort should cause.

From the clinic

Get the two-legged wall sit or the ball wall squat steady first. Lifting one foot moves the whole load onto the other leg, and balancing on that leg against a rolling ball is harder than it looks. Inflate the ball until it feels firm, choose a non-slip floor, and place a solid chair or counter within arm's reach to steady yourself as you lift the foot and as you stand back up. If you have fallen in the past year or feel unsteady on one leg, ask your physio before you try this version.

If you have high blood pressure, breathe steadily through every hold and never hold your breath. With a heart condition or high blood pressure, check with your doctor before you start. If chest pain, pressure or tightness does not ease quickly when you rest, spreads to your arm, neck, jaw, stomach or back, or comes with sweating, feeling sick, feeling light-headed or being short of breath, call emergency services straight away, as this can be a heart attack. If it eases quickly and none of these happen, get medical advice the same day, and do not exercise again until you have been checked. If you faint while exercising, call emergency services, even if you feel fine again quickly.

If you have had a hip or knee replacement, get the go-ahead from your surgeon or physio before you try the single leg wall sit. Some operations limit this kind of work for the first months, so the timing depends on your surgery. After other knee surgery, such as a ligament repair or meniscus surgery, ask your physio before you try it and how deep you may go.

Written and checked by the PocketPhysio editorial team. Last updated 2026-09-26.

This page is general education, not a diagnosis or a personal treatment plan. If you have pain, an injury or a health condition, see a physiotherapist or doctor before starting new exercises.

Single leg wall sit with a ball