What is the reverse crunch?
The reverse crunch is a floor ab exercise where the pelvis, not the torso, does the curling. Lying on your back with hips and knees bent to 90 degrees, you tilt your pelvis, peel your hips a few centimetres off the floor and roll your knees toward your chest, then lower everything under control. The key is a deliberate pelvic curl rather than a leg swing: the rectus abdominis shortens from the bottom up. Because the head never moves, it suits anyone who gets neck pain from regular crunches, and it teaches the posterior pelvic tilt that protects your spine in planks and leg raises.
How to do the reverse crunch
- 1
Set up at 90/90
Lie on your back, hips and knees bent to 90 degrees, shins parallel to the floor. Arms by your sides, palms down, lower back gently pressed into the floor.
- 2
Tilt, then curl
Exhale and tilt your pelvis toward your ribs first, then peel your hips off the floor, rolling your knees toward your chest. The tilt starts every rep, not the legs.
- 3
Pause at the top
Knees over your chest, hips a few centimetres off the floor. Squeeze your abs for a full second with no rocking and no push from the arms.
- 4
Lower slowly
Roll your spine back down over 2-3 seconds until your hips rest on the floor and your shins are parallel again. Don't let the feet drop or the back arch.
Pro tip
Imagine your hips being lifted by your abs, not thrown by your legs. If you can't pause for one full second at the top, momentum was doing the work: slow down and shorten the range.
Common mistakes
Swinging the knees.
Rocking the legs builds momentum and turns the abs into spectators. Start every rep from a dead stop and let the pelvic curl do the lifting.
Dropping fast on the way down.
The slow lowering is half the exercise. Rushing it throws away the eccentric work and lets the back arch at the bottom.
Pushing through your hands.
White-knuckling the floor levers the hips up with your arms. Keep the arm pressure light; it's a balance aid, not an engine.
No pelvic tilt.
Raising the knees without curling the pelvis is just a hip flexor march. Tilt the pelvis toward the ribs first on every single rep.
Variations and progressions
Easier
Pelvic tilt knee tuck
Keep your hips on the floor and simply tilt the pelvis while drawing the knees in. You learn the tilt pattern without having to lift anything.
Harder
Decline reverse crunch
On a decline bench with your head above your hips, holding the bench behind you, gravity fights the curl through the whole range. Brutal and strict.
No floor space?
Captain's chair leg raise
The captain's chair gives you the same bottom-up ab curl standing on your forearms, and makes it easy to load the pattern as you progress.
How to program it
Three protocols by goal. Pick one per cycle and aim for progression on load or distance.
| Goal | Sets × distance | Load | Rest |
|---|---|---|---|
| Technique | 3 × 8-10 | Bodyweight, 1 s pause | 60 s |
| Hypertrophy | 4 × 12-15 | Bodyweight, 3 s lowering | 60-90 s |
| Progression | 3 × 10-12 | Decline bench | 90 s |
Reverse Crunch FAQ
Do reverse crunches target the lower abs better than regular crunches?
Somewhat. The rectus abdominis is one muscle, but EMG studies show modestly higher lower-region activation when the pelvis curls toward the ribcage instead of the other way round. Don't expect magic: the bigger wins are practical. No neck strain, a trained posterior pelvic tilt, and an eccentric you can actually control. Do both movements and you cover the whole muscle.
Why do I only feel reverse crunches in my hip flexors?
Because your knees are moving but your pelvis isn't curling. Hip flexors lift the knees; abs curl the pelvis. Shorten the range, slow right down, and start each rep by tilting your pelvis toward your ribs before anything else moves. If that still fails, do a week of pelvic tilt knee tucks to groove the pattern first.
How many reverse crunches should I do a day?
None daily, ideally. Abs are a muscle like any other: train them 2-3 times per week with 3-4 hard, strict sets, then let them recover. When 15 slow reps feel easy, progress to a decline bench or a 4-second lowering instead of chasing rep counts into the hundreds. A hundred sloppy reps builds hip flexor endurance, not a visible six-pack.
