Reverse Crunch
Lift the hips, not the feet. The reverse crunch curls the knees toward the chest by lifting the hips off the floor, which trains the bottom half of the movement that sit-ups leave alone. Swinging the legs and letting momentum do the lifting is the fault. If your ab work has all been crunches, this is the half you have been missing.
Setup
- Lie flat, hands by the hips or holding something behind your head.
- Knees bent, feet off the floor.
How To Do It
- Curl the knees toward the chest by lifting the HIPS off the floor.
- The movement is the pelvis tilting, not the legs swinging.
- Lower slowly until the hips return to the floor.
Breathing
Exhale as the hips lift.
Common Mistakes
- Swinging the legs and letting momentum lift the hips.
- Only moving the knees while the pelvis never leaves the floor.
Programming It
Three sets of 10-20.
Why This Exercise Works
Curling the pelvis toward the ribs loads the abs from the bottom end, which is the half a sit-up mostly ignores. The lower back should stay flat and the hips should actually lift. If only the legs move, the hip flexors are doing it.
Where You Should Feel It
The lower abs curling the pelvis toward the ribs. If only your legs move and your hips stay down, the hip flexors are doing it and the abs are not.
Where It Fits in a Program
Trains the abs from the bottom up, which most people never do. This is main-lift work. Put it first, when your technique is still honest.
Progressing and Regressing It
To progress the reverse crunch: slow the lowering, or straighten the legs. To regress it: keep the knees bent and reduce the range.
Who It's For
Anyone whose ab work is all sit-ups. This trains the bottom half of the movement that crunches ignore.
Equipment and Substitutions
Nothing to buy and nowhere to be, which is the point. If it is too easy, the harder variations below are the progression, not added weight.
Related Exercises
- Hanging Leg Raise · Abs, Hip Flexors
- Hanging Knee Raise · Abs, Hip Flexors, Grip
- V-Up · Abs, Hip Flexors
- Bicycle Crunch · Abs, Obliques
- Hollow Body Hold · Abs, Deep Core
- Kneeling Cable Crunch · Abs
- Ab Wheel Rollout · Abs, Lats, Shoulders
- Hollow Rock · Abs, Deep Core
Common Questions
What muscles does the reverse crunch work?
The reverse crunch primarily trains the abs, hip flexors.
How many sets and reps should I do?
Three sets of 10-20.
What are the most common reverse crunch mistakes?
Most often: swinging the legs and letting momentum lift the hips; only moving the knees while the pelvis never leaves the floor.
Can I do this without any equipment?
Yes. This version needs no equipment at all. It trains the abs, hip flexors using bodyweight alone, which is why it travels well and works as a warm-up, a substitute, or a full session on its own.
Is this safe if I have an existing injury?
The lower back does real work in the reverse crunch. If you have a history there, keep the load conservative and stop the moment a rep reproduces your own pain rather than ordinary effort. Not medical advice.