Cocoons
Cocoons are a bodyweight ab exercise where you lie flat and curl your whole body into a tight ball, bringing your knees and chest together at the same moment. Unlike a crunch, which only lifts your shoulders, this move asks your upper and lower body to fold in together, training the abdominals through a bigger range in one rep. It's a beginner-friendly move that suits anyone who wants more out of floor ab work without adding equipment.
Why it works
A standard crunch trains spinal flexion, curling your ribs toward your pelvis. A reverse crunch trains the opposite half, curling your pelvis toward your ribs. Cocoons combine both directions in a single rep, so your abdominals shorten from both ends at once instead of doing half the job while the other half stays still. That double fold is also why the exercise feels more like a full-body squeeze than a typical crunch, even though the abs are still doing the majority of the work.
Set up
- Lie flat on your back on a mat, legs extended and arms stretched overhead.
- Press your lower back gently into the floor before you start.
- Point your toes and reach your fingertips away from each other to start each rep from a long, extended line.
- Keep your neck relaxed, chin slightly tucked, rather than jamming it forward.
How to do it
- Simultaneously lift your shoulders and knees off the floor, curling toward each other.
- Bend your knees as you bring them up, aiming to touch your shins near your chest.
- Reach your hands toward your shins as you curl, meeting in the middle like closing into a ball.
- Hold the fully curled position for a beat, squeezing your abs.
- Uncurl with control, extending back to the long starting line without letting your heels or head slam down.
- Keep the motion smooth throughout; the fold and the extension should take about the same amount of time.
Form cues
- Knees and chest arrive together, not one before the other.
- Lower back stays lightly pressed down, not arched, at the start and end of each rep.
- Neck stays relaxed, following the curl instead of leading it.
- Uncurl as slowly as you curled in.
Breathing: Exhale as you curl into the ball, inhale as you extend back out to the starting line.
Common mistakes
Using momentum to rock into the curl instead of controlling it with the abs.
Fix: Slow the tempo down until you can pause briefly at the top of the curl; a rocking rep skips the muscular squeeze that makes the exercise work.
Letting the lower back arch hard off the floor as the legs extend back out.
Fix: Keep a slight bend in the knees at full extension instead of locking them straight; a small bend protects the lower back while you build control.
Pulling on the neck with the hands to help the shoulders lift.
Fix: Keep your hands reaching toward your shins instead of behind your head; the abs should lift your shoulders, not your arms.
How to program it
- This is light bodyweight core work, so it recovers quickly and can be trained three to four times a week without much cost.
- Sets of 10 to 15 controlled reps build more than rushing through 20 sloppy ones.
- Slot it into the end of a session as finishing ab work, since it doesn't need to be fresh legs or a fresh back to perform well.
- If the full fold feels too much at first, break it into a reverse crunch and a regular crunch separately before combining them.
Safety notes
- Keep the lower back in gentle contact with the floor rather than letting it arch, especially as your legs extend back out.
- Stop if you feel the movement in your hip flexors or lower back more than your abs, and shorten the range until the abs take over again.
Exercise profile
- Force
- Pull
- Mechanics
- Compound
- Category
- Strength
Frequently asked questions
How many reps of cocoons should I do?
Two to three sets of 10 to 15 controlled reps is a good target. Quality of the squeeze matters more than rushing through extra reps.
What can I do instead of cocoons if my lower back is sensitive?
Break the movement apart: do a reverse crunch for the lower half and a regular crunch for the upper half, then combine them once your lower back tolerates the full range.
Why do I feel cocoons in my hip flexors instead of my abs?
That usually means the legs are doing more of the lifting than the torso. Slow down and focus on curling your ribs toward your pelvis at the same time your knees come up, rather than just swinging your legs.
Can I do cocoons every day?
Yes, as light bodyweight ab work it recovers quickly enough for daily practice. Keep the reps controlled rather than rushed even on days you do it as a quick warm-up.