A curl up is a small lift of your head and shoulders while you lie on your back with your knees bent. Your stomach muscles do the lifting and your straight arms reach forward beside your thighs. You stop once the tops of your shoulder blades clear the mat, then lower slowly. It is much smaller than a full sit-up, and your lower back stays on the mat the whole time. Most of the work falls on the long muscle down the front of your stomach (rectus abdominis).

How to do the curl up

Start on your back on a mat with your legs out straight, then bend your knees one at a time until your feet are flat and a little apart. Let your lower back keep its small natural hollow rather than pressing it flat.
Rest your arms straight on the mat by your sides.
Nod your chin in slightly, as if holding a small ball under it, so the back of your neck stays long.
Breathe out and raise your head and shoulders. Let your straight arms lift just off the mat and reach forward beside your thighs, toward your knees, until the tops of your shoulder blades clear the mat.
Pause for a moment, then breathe in as you lower back down slowly, letting your arms and head rest on the mat before the next one.

What you should feel

Effort across the front of your stomach, strongest at the top of each lift. If your neck tires before your stomach does, rest and reset your chin position before you carry on.

Common mistakes

Flinging the arms to swing yourself up instead of curling with the stomach.
Jutting your chin out, or jamming it hard onto the chest.
Coming up so high that your lower back peels off the mat and the curl turns into a sit-up.
Holding your breath while you curl up.

How often

Many programs start with 1 to 3 sets of 8 to 15 slow curl ups, a few days a week. Your physio will adjust this.

Stop and check with your physio if

Pain in the neck that gets worse as you go, or pain, tingling or numbness running into an arm.
Pins and needles in your arm or hand that do not go away after you stop, or part of your arm or hand goes numb. Get medical advice the same day. If one side of your face or body suddenly goes numb or weak, or your speech becomes slurred or muddled, call emergency services, even if it goes away.
Pain from your lower back spreading into a leg, or a leg that tingles or goes numb.
A bulge, doming or ridge down the center of your stomach as you lift, or pain near a surgical scar. Stop and ask your physio.

From the clinic

Reaching forward with straight arms, as in the video, is the easiest arm position, and it keeps your hands well away from your neck. Crossing your arms on your chest makes each curl a little harder. The voice guide mentions a slightly arched back, but aim for your normal small hollow rather than an exaggerated arch. If your neck starts to complain, the McGill curl-up is a smaller, held version, and the dead bug trains the stomach without lifting your head at all.

Curl ups load the stomach wall with every repetition. If you are pregnant, have had abdominal or back surgery or have a hernia, ask your physio or doctor before you do curl ups. If you have recently given birth, including by cesarean section, or you have a gap down the middle of your stomach muscles (diastasis recti), ask your physio, midwife or doctor first. If you have high blood pressure, breathe steadily through every repetition and never hold your breath.

Curl ups are usually left out for people with osteoporosis, because bending the spine forward over and over can raise the risk of a spine fracture. If you have osteoporosis or have had a fracture in your spine, ask your physio for a core exercise that keeps your back straighter.

Written and checked by the PocketPhysio editorial team. Last updated 2026-09-28.

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.

Curl up