Reverse Crunch
The reverse crunch has you lying on your back, knees bent toward your chest, curling your hips off the floor using your lower abs rather than swinging your legs for momentum. It isolates the lower portion of your abdominals in a way that a standard crunch, which mostly curls the upper spine, doesn't reach as directly. It suits anyone building foundational core strength and pairs naturally with a standard crunch to cover both ends of the abdominal wall.
Why it works
A regular crunch curls your upper spine toward your hips; the reverse crunch flips that action, curling your hips and pelvis toward your ribs instead. That small directional flip shifts more of the demand onto your lower abdominals, which get comparatively less work from most other core exercises. Because the range of motion is small and your pelvis has a lot of weight to move, even a short, controlled curl can create real tension in that specific region, which is exactly why swinging the legs for momentum defeats the purpose entirely.
Set up
- Lie on your back on a mat with your knees bent and lifted so your thighs are roughly vertical.
- Rest your arms flat on the floor beside you or lightly under your lower back for support.
- Keep your lower back gently pressed into the mat before starting.
How to do it
- Curl your hips and knees up and in toward your chest using your lower abs, not momentum.
- Let your hips lift slightly off the floor at the top of the movement.
- Pause briefly at the top, feeling the squeeze in your lower abdominals.
- Lower your hips back down with control until your lower back settles onto the mat.
- Stop just before your feet would touch the floor and begin the next rep.
- Keep the whole movement slow and deliberate rather than swinging.
Form cues
- Curl the hips, don't swing the legs.
- Small range, real squeeze.
- Lower back stays supported, not arching.
- Slow down, no momentum.
Breathing: Exhale as you curl your hips up, inhale as you lower them back down.
Common mistakes
Swinging the legs using momentum instead of curling with the abs.
Fix: Slow the tempo down dramatically; if you can't control the descent, the legs are doing the work instead of the abs.
Arching the lower back at the bottom of each rep.
Fix: Stop the lowering phase just before the lower back would arch, keeping constant gentle tension in the abs.
Pulling with the arms or shoulders to help lift the hips.
Fix: Keep your arms relaxed on the floor; the hip curl should come entirely from the lower abs.
Chasing a high rep count with sloppy, fast reps.
Fix: Cut the rep count and slow down instead; 10 controlled reps train more than 30 rushed ones.
How to program it
- Start with 2 or 3 sets of 10 to 15 slow, controlled reps, two or three days a week.
- It pairs well with a standard crunch or plank in the same session to train both the upper and lower abs.
- Progress by slowing the tempo further or adding a brief hold at the top before adding an incline.
- Once bodyweight reps feel easy for 3 sets of 15, the decline version or hanging leg raise are the natural next steps.
Safety notes
- If your lower back arches no matter how small the range, shrink the movement further or switch to the dead bug until control improves.
- Keep the motion slow; a fast, swinging reverse crunch can strain the lower back rather than train the abs.
Exercise profile
- Force
- Pull
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
How many reverse crunches should I do?
Ten to fifteen slow, controlled reps, for 2 or 3 sets, is a solid starting point. Quality of the curl matters far more than the total count.
Reverse crunch vs regular crunch: what's the difference?
A regular crunch curls the upper spine toward the hips, emphasizing the upper abs. The reverse crunch curls the hips toward the ribs instead, emphasizing the lower abs. Using both covers the abdominal wall more completely than either alone.
Why do I feel reverse crunches in my hip flexors instead of my abs?
This usually happens when the legs swing with momentum rather than the hips curling under control. Slow down significantly and focus on lifting the hips using the lower abs, not the thighs.
Can reverse crunches hurt your lower back?
Done with a swinging, uncontrolled motion, yes, they can strain the lower back. Keeping the range small, the tempo slow, and the lower back gently supported on the mat keeps the exercise where it belongs, in the abs.