Reverse Crunch: how to do it right
In short: The reverse crunch isolates the lower abs by curling the pelvis toward the ribcage, with maximum tension at mid-range.
How to do it, step by step
- 1Lie on your back, hands along your body or under your glutes, knees bent at 90 degrees above your hips.
- 2Curl your pelvis upward by lifting your sacrum, as if bringing your knees toward your chest without pulling them with momentum.
- 3Rise until your lower back leaves the floor, without swinging your legs.
- 4Lower slowly under control, without fully resting your pelvis between reps.
- 5Keep a continuous, controlled rhythm, 2 seconds on the way down, with no jerks.
The mistake to avoid
Don't throw your legs with momentum. Curl your pelvis slowly.
Other common mistakes
- You use leg momentum to propel yourself, which unloads the abs: slow down and think about curling the pelvis, not throwing your knees.
- You don't lift the sacrum and just move your thighs: that's the hip working, focus on the posterior tilt of the pelvis.
- You uncurl too fast and bounce at the bottom: brake the return phase to exploit the eccentric.
- You arch your lower back as you rise: keep your lower back pinned to the floor to protect your spine.
Muscles worked
- Main:
- Abs
The rectus abdominis, especially its sub-umbilical portion, leads the pelvic curl. The transverse abdominis braces and stabilizes the trunk. The obliques accompany the posterior tilt and prevent lateral tipping. The rectus abdominis doesn't shorten in separate segments, but the posterior tilt action preferentially loads the lower part.
What to replace it with
Same muscle, same part of the movement: these exercises do the same job.
Frequently asked questions
How do I do this exercise?
Lie on your back, hands along your body or under your glutes, knees bent at 90 degrees above your hips. Curl your pelvis upward by lifting your sacrum, as if bringing your knees toward your chest without pulling them with momentum. Lower slowly without fully resting your pelvis between reps.
How far should I go?
The tension is maximal at mid-range, when the sacrum lifts off and your lower back presses into the floor. At the bottom the lever arm is short, at the top the tension drops once the pelvis is curled. Stay in a continuous back-and-forth around this middle zone, with no dead stop at the bottom or lockout at the top, to keep your abs under constant tension.
I don't feel anything, is that normal?
You should feel the lower abs, the sub-umbilical portion. Place a hand in the small of your back, your mission is to crush that hand into the floor on every rep. This image forces the real posterior tilt of the pelvis and stops you from cheating with your legs. If you mostly feel your thighs, you're moving the hip instead of curling the pelvis.
How fast should I do the movement?
Curl the pelvis firmly then brake the descent over 2 to 3 seconds as you uncurl. It's this eccentric braking that does the work, don't bounce at the bottom. Keep a continuous, controlled rhythm with no jerks.
How should I breathe?
Breathe out as you curl the pelvis, when the abs contract. Breathe in as you uncurl in a controlled way. Keep the transverse engaged the whole time, belly drawn in, to lock the trunk and keep your lower back from arching.