Core · Spinal flexion

Reverse Crunch

The reverse crunch is a core exercise where you lie on your back with your knees bent and curl your hips off the floor toward your chest. Moving the pelvis instead of the shoulders biases the lower abs and takes strain off the neck, which makes it a popular beginner alternative to the crunch.

Also known as: Reverse crunches, Hip curl, Lying pelvic curl

Muscle group: Core
Movement pattern: Spinal flexion
Type: Isolation
Equipment: Bodyweight, Mat
Difficulty: Beginner

What muscles does the reverse crunch work?

Primary movers

Rectus abdominis

Assisting muscles

Hip flexors
Obliques
Transverse abdominis

The rectus abdominis curls the pelvis toward the ribcage, which means the lower fibres do much of the work. The fixed upper body makes the pelvis the moving end.

The hip flexors help bring the knees toward the chest, but the main goal is to roll the hips, not just swing the legs.

The obliques and transverse abdominis stabilise the trunk. Keeping your lower back pressed down at the start protects the spine.

The move is easy on the neck because your head stays on the floor, a good fit if standard crunches bother your neck.

How to do the reverse crunch

Setup

1
Lie on your back with your arms by your sides, palms down.
2
Bend your knees to 90 degrees with your thighs vertical.
3
Press your lower back into the floor.
4
Brace your abs.

Execution

1
Curl your hips off the floor, bringing your knees toward your chest.
2
Think of rolling your pelvis toward your ribs, not swinging your legs.
3
Pause briefly at the top.
4
Lower your hips slowly back to the floor.
5
Exhale as you curl up.

Common reverse crunch mistakes

Swinging the legs

Momentum lifts the hips and the abs do less.

The fix: Slow down and roll the pelvis instead.

Pushing with the arms

It takes the work off the abs.

The fix: Use your hands only for light balance.

Dropping the hips fast

You lose the lowering phase.

The fix: Lower for two to three seconds.

Letting the lower back arch

The lower back absorbs the load as the legs go down.

The fix: Keep your lower back pressed down.

How many sets and reps?

Goal	Sets	Reps	Load	Rest
Core strength	3	10–15	Bodyweight, slow tempo	45–60 s
Progression	3–4	10–15	Straight legs or a weight between the feet	60 s
Beginner	2–3	8–12	Small range, feet down between reps	45–60 s

Use the reverse crunch as a lower-ab finisher or as a gentler option when upper-body crunches bother your neck. Control matters more than speed.

Running the reverse crunch in your next block? Hercules logs every set, shows last session's numbers before you lift, and suggests when to add weight.

Get it on Google Play

Frequently asked questions

Do reverse crunches work the lower abs?

They bias the lower fibres of the rectus abdominis, though the whole muscle works.

Are reverse crunches good for beginners?

Yes. They are easy on the neck and simple to learn.

Why do I feel it in my hip flexors?

You are swinging your legs. Roll your pelvis instead and slow down.

How many reps should I do?

Three sets of 10 to 15 slow reps.

Hercules tracks every reverse crunch you log, shows you last session's numbers before you lift, and flags when your progress stalls.

Get it on Google Play

Related exercises

Core