reckonerReverse crunch
A crunch curls the top of the torso toward the hips. A reverse crunch curls the hips toward the torso. Same muscle, opposite end, and the difference on the floor is whether your backside actually leaves it or whether you just swing your knees.
Curl the hips up, keep the back down.
- Pattern
- Core flexion
- Trains
- Abs
- Kit
- Bodyweight, floor
- Loading
- Your own bodyweight
- Reckoner prescribes
- 3 sets of 10 to 15 reps at RPE 8
- Progression step
- Nothing to add, so the sets climb instead
- Skill
- Simple to learn
- Recovery cost
- Very low
- Not prescribed if you have declared
- Lower back
Muscles worked
How to do it
Lie down and anchor yourself
Arms flat beside you or holding something behind your head, knees bent and pulled up over the hips. Press the lower back into the floor before anything moves.
Curl the hips up, not the knees back
Lift your backside off the floor by rolling your pelvis toward your ribs. It is a small movement. If your hips never leave the floor, no reverse crunch happened.
Pause at the top
Hold the curled position for a beat where the abs are shortest. The pause is what stops the next rep being a swing, and it is the difference between four honest reps and fifteen worthless ones.
Lower one vertebra at a time
Put the hips back down slowly and keep the lower back in contact with the floor throughout. Then start the next rep from still.
What goes wrong
Swinging the legs to lift the hips
A kick of the knees toward the chest throws the hips up and it looks identical from a distance. Momentum did it, and the abs got a moment of holding on rather than a rep.
Pulling with the hip flexors
Bringing the thighs toward the chest is hip flexion and it can happen without the pelvis rotating at all. The tell is that the hips stay glued to the floor while the knees travel.
Going for a high rep count
Because the range is short people chase numbers. A short range done properly is a hard exercise, and a long set of it usually means the swing has arrived.
How Reckoner progresses this lift
Six weeks of this lift, run through the real engine. Nothing below was typed in: the prescription, the decision and the sentence beside it all come from the same code that writes your week.
| Week | Prescribed | What it did |
|---|---|---|
| 1 | 3 x 10 | More reps 10 → 11 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 2 | 3 x 11 | More reps 11 → 12 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 3 | 3 x 12 | More reps 12 → 13 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 4 | 3 x 13 | More reps 13 → 14 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 5 | 3 x 14 | Deload 40% of sets offFive weeks of building, then one week lighter. About 40% of the sets come off. The load holds and your reps stay where you earned them, so you keep the strength and lose the fatigue. |
| 6 | 2 x 14 | More reps 14 → 15 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. The lighter week is over, so this is back to three sets. |
Real engine output, not an illustration. Every row was produced by running the engine itself when this page was generated.
The full rule, and why the reps move before the load does, is in how Reckoner decides to add weight.
Questions people ask
Does the reverse crunch hit the lower abs?
It is a good abdominal exercise and it is not a way of selecting a region. Measured on an incline, the reverse crunch came out among the most effective exercises for the upper and the lower rectus abdominis alike, and among the highest for hip flexor activity too, which the authors note may be a problem for some people with low back trouble1.
Should my hips actually come off the floor?
Yes, and it is the one thing that decides whether you are doing this exercise or not. If they stay down you have performed hip flexion with a bent knee, which the hip flexors will happily do all day.
How does Reckoner treat this against a normal crunch?
They sit in the same family, so it will offer one in place of the other rather than prescribing both, and your history stays in one line when it does.
Similar movements
There is no load to ease on this lift, so Reckoner offers one of these the first time it stalls. Each of them has a page.
Sources
- Escamilla and colleagues, Physical Therapy, 2006. Electromyographic analysis of traditional and nontraditional abdominal exercises: implications for rehabilitation and training twenty-one healthy adults across traditional and nontraditional abdominal exercises, with the wheel roll-out, the pike, the knee-up, the hanging knee-up on straps and the inclined reverse crunch highest for upper and lower rectus abdominis, internal oblique and latissimus dorsi, and with the wheel pike and knee-up, the inclined reverse crunch and the bent-knee sit-up also highest for rectus femoris, which the authors note may be a problem for some people with low back trouble