The seated side lean onto a ball is a sitting exercise where you rest one arm on a gym ball beside you and lean your body toward it. Your weight moves onto the hip on that side and the other buttock lifts slightly, while your shoulders stay as level as you can keep them. The ball holds part of the weight of your arm and upper body, so you can practice taking weight through one side with some support. The voice guide places the ball on the weaker side.

How to do the seated side lean onto a ball

Sit on a firm bed or bench with your thighs supported and your feet flat, about hip width apart. If the bed is high, put a firm step under your feet so they rest flat, as in the video.
Place a gym ball on the bed right beside your weaker side, close to your hip, and rest that arm on top of it with the elbow slightly bent.
Keeping your shoulders as level as you can and your head upright, lean slowly toward the ball so your forearm and upper arm settle onto it. In the video the upper body tilts a little toward the ball, and that is fine.
Let your weight move onto the hip on the ball side, so the buttock on the other side lifts a little off the bed.
Hold for a few seconds, then come back up to sit tall in the middle.

What you should feel

Weight through the hip on the ball side, and effort in the waist muscles on the opposite side as they hold you there. The arm on the ball should feel supported, not strained.

Common mistakes

Pressing hard into the ball, so it rolls away from you.
Letting the shoulder on the ball side push up toward your ear.
Collapsing sideways onto the ball instead of leaning with a long trunk.
Twisting round to face the ball.

How often

Physios often start with 5 to 10 leans, holding each for 5 to 10 seconds, once or twice a day. Your physio will adjust this.

Stop and check with your physio if

You feel dizzy, faint or unsteady. Stop and get medical advice the same day. If you faint, it does not settle within a few minutes of sitting still, or you cannot stand or walk steadily, call emergency services.
The ball rolls away and you cannot get back to the middle without help.
Pain in the shoulder of the arm on the ball, or pins and needles or numbness in that arm or hand.

From the clinic

The main risk here is the ball rolling away. Pick a size whose top sits at about shoulder height beside you, as in the video, and wedge it against a wall or headboard, or have a helper hold it still. If you have neither, a stack of firm pillows beside you gives similar support without rolling. Lean on it gently. Pushing is what sends it off.

Sit on a bed or bench that is firm and does not move, keep your feet flat and clear the space around you. Have another adult with you on the ball side, ready to steady the ball and catch you if it slips. This page explains the general technique, not a stroke rehab program. Talk to your physio before practicing at home if you have weakness on one side from a stroke or a similar brain or nerve condition.

A sudden loss of balance is different. Call emergency services straight away for any sign of a stroke, even if it goes away: sudden dizziness with unsteadiness or falling over, a face that droops on one side, an arm you cannot lift or keep up, slurred or muddled speech, weakness or numbness on one side of your body or face, sudden blurred vision, double vision or loss of sight, or a sudden severe headache. If one side is already weak or numb from an earlier stroke, new or suddenly worse weakness or numbness is a sign, and every other sign in this list still counts.

The arm on the ball is often the weaker one. Let the ball carry its weight and keep the shoulder low and relaxed, rather than pushing down through a weak arm. If someone lifts the arm onto the ball for you, they should support it under the elbow and forearm and never pull it by the hand. If that shoulder is painful, droops away from its socket (subluxation) or cannot hold its position yet, ask your physio how to set the arm on the ball before you begin. If you have had surgery on your spine, chest or heart in recent months, get the go-ahead from your surgical team or physio first.

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.

Seated side lean onto a ball