Hip extension over a gym ball is a leg lift done on hands and knees with a large exercise ball under your stomach. You straighten one leg and raise it behind you to about the height of your body, then lower it and switch. The buttock muscle (gluteus maximus) does the lifting, while the deep tummy muscles hold your back still. With the ball taking the weight of your trunk, you can think only about keeping your back still while the leg moves.

How to do the hip extension over a gym ball

Kneel on a mat with a gym ball in front of you. Lean forward over it so it supports your stomach, then place your hands flat on the floor under your shoulders. Your knees and toes stay on the floor behind the ball.
Straighten your back so it is flat, without an arch, and tuck your chin in a little so your neck lines up with your spine.
Gently draw your belly button in and lightly tighten your pelvic floor, at about 20 to 30 percent of your full effort. Keep breathing steadily from your tummy.
Straighten one leg and lift it behind you until it is about level with your body, as in the video. Hold it there for a few seconds. Your back and hips should not move as the leg rises.
Lower the leg until the knee is back on the floor, then do the same with the other leg.

What you should feel

Work in the buttock and the back of the thigh of the lifting leg, and light, steady effort in your tummy. Your lower back should feel quiet.

Common mistakes

Lifting the leg higher than your body, so the lower back arches to get it there.
Rolling the hips or tipping toward the supporting side as the leg lifts.
Letting go of the gentle tummy and pelvic floor hold, or holding your breath instead.
Rushing the leg up and down, so the ball rolls under you.

How often

A usual start is 8 to 12 lifts on each leg for 2 or 3 rounds, with a 3 to 5 second hold at the top of each lift. Your physio will adjust this.

Stop and check with your physio if

Pain in your lower back that is sharp or builds with each lift.
Sharp pain in the hip, buttock or the back of the thigh.
Tingling, numbness or pain spreading down the leg.

From the clinic

The voice guide only mentions lifting the foot off the floor, but the video shows the whole leg straightening and rising to the height of the body, so that is the version described here. Choose a ball that lets your hands and knees rest on the floor at the same time, and pump it up firm. If you are new to the movement, get it steady on the floor first with quadruped hip extension.

Kneeling can be hard on sore knees, so put a folded towel under them. Leaning on your hands may not suit painful wrists either. If you are pregnant, check with your physio before lying over a ball.

If you have had a hip replacement, get the go-ahead from your surgeon or physio before you try this exercise. A lift that goes past level takes the hip back behind the line of your body, and many surgeons ask you to avoid that for the first months after some operations, especially when the hip was replaced from the front. Kneeling over the ball also bends both hips to about a right angle, and after a hip or knee replacement, kneeling may be uncomfortable for a while.

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.

Hip extension over a gym ball