Reverse Crunch
The reverse crunch is a floor exercise for your abs: lying on your back with your knees bent, you curl your pelvis off the floor and roll your knees toward your chest. It trains the rectus abdominis from the bottom up instead of lifting your shoulders, and it needs nothing but a mat.
How to do the reverse crunch
Lie face up on a mat, arms resting next to your body with the palms flat on the floor.
Lift your legs with your knees bent until your thighs point straight up and your shins are roughly level with the floor.
Breathe out and pull your belly button in, then curl your pelvis up off the floor so your knees move toward your chest.
Stop when your hips and lower back have rolled off the mat, without swinging your legs over your head.
Roll your pelvis back down under control, one part of your spine after another, until your hips touch the mat.
Keep your feet off the floor and start the next rep from there.
Setup for the reverse crunch
Lie on your back on a mat, arms along your sides with your palms flat on the floor. Lift your legs one at a time until your thighs point straight up and your knees are bent, so your shins are about level with the floor. Press your lower back gently into the mat. This is your starting position for every rep.
Breathing and bracing
Breathe in at the start, then breathe out as you curl up and draw your belly button in. Breathing out helps your rib cage move down toward your pelvis, which is the motion you are training. Breathe in again as you lower.
Curling the pelvis
The rep is a curl, not a leg lift. Keep the angle at your knees the same and roll your pelvis toward your rib cage, so your tailbone and then your lower back lift off the mat. Your knees move toward your chest as a result, not as the cause. Stop when your hips have rolled off the floor; swinging your legs further over your head adds momentum, not work.
Tempo and range of motion
Curl up smoothly, pause briefly at the top and roll down at least as slowly as you rolled up. Touch the mat with your hips, keep your feet off the floor and start the next rep without a rest at the bottom. Light loads build muscle about as well as heavy ones when sets are taken to or close to failure, so clean, slow reps with your body weight are enough.
Making it harder
Once you reach 15 clean reps in every set, the next step is a harder version rather than more reps. Lying on a bench set to an incline, head higher than hips, makes you lift your pelvis against more of your body weight. Hold the bench behind your head for support.
Muscles worked by the reverse crunch
- Primary
- Abs
- Secondary
- Obliques
- Hip flexors
The rectus abdominis, the six-pack muscle, does the work: it curls your pelvis toward your rib cage. The obliques on your sides help, and the hip flexors hold your legs in position. In an EMG study of abdominal exercises, a reverse crunch on an incline ranked among the highest for the upper and lower rectus abdominis and the internal oblique, and it also produced high activity in the rectus femoris, a hip flexor.
Common reverse crunch mistakes
Swinging the legs
A kick lets momentum lift your hips, so your abs only catch the weight. Start each rep from still legs and curl slowly.
Moving only your legs
If your knees come toward your chest but your pelvis stays on the floor, your hip flexors do the work. Think of rolling your tailbone up off the mat.
Pushing with your hands
Pressing your palms hard into the floor helps lift the hips with your arms and shoulders. Keep your hands resting flat with light pressure.
Dropping the hips
Letting your pelvis fall back to the floor skips the half of the rep that controls your trunk. Roll down at least as slowly as you rolled up.
Arching your lower back
When your legs drift away from you at the bottom, the lower back lifts off the mat and the abs lose tension. Keep your knees above your hips.
Reverse crunch tips from the Muscla training logic
- Muscla adds abs work when time is left after your main muscles, never at their cost, and plans no warm-up sets for body-weight exercises.
- End each set with about one rep in reserve, two if you are new to training. Muscla aims isolation work at one rep in reserve.
- Rest 75 seconds between sets when you train for muscle, 90 seconds for strength and 60 seconds for other goals.
- Earn progress with reps: as a body-weight exercise the reverse crunch runs at 8–15 reps. Add one rep at a time until every set reaches 15.
- Once every set reaches 15, Muscla keeps you at 15 until the block ends instead of adding a 16th rep. To make the exercise harder, do it on a bench set to an incline, head higher than hips.
Reverse crunch sets and reps
| Goal | Reps | Rest |
|---|---|---|
| Strength | 8–15 | 90 s |
| Muscle | 8–15 | 75 s |
| Lose fat | 8–15 | 60 s |
| Fit | 8–15 | 60 s |
| Comeback | 8–15 | 60 s |
Bodyweight: one range for every goal.
The table shows the app's range for body weight: 8–15 reps per set, whatever your goal, and the app does not ask “How heavy was that?” here. Once every set reaches 15, you stay at the top of the range until the block ends. After every third 4-week block comes a deload week with one set fewer.
Reverse crunch alternatives
- Cable Kneeling Crunch
- Hanging leg raise
- Dead Bug
- Lying leg raise flat bench
- Bodyweight incline side plank
- Crunch floor
- Band horizontal pallof press
- Kneeling plank tap shoulder (male)
- Front plank with twist
- Power point plank
Reverse crunch questions
Do reverse crunches work the lower abs?
They work your whole rectus abdominis. In an EMG study, the upper and lower parts of the muscle did not differ in activity within or between exercises, so there is no exercise that trains only the lower abs.
Are reverse crunches better than crunches?
In a comparison of abdominal exercises, a reverse crunch on an incline activated the rectus abdominis and the internal oblique more than many traditional exercises. It also used the hip flexors strongly, so both have a place.
Why do I feel reverse crunches in my hip flexors?
Your hip flexors hold your legs up, and they work hard in this exercise. If you feel mostly them, you are probably moving your legs instead of your pelvis: think of curling your tailbone off the floor.
Should my feet touch the floor between reps?
No. Lower your hips to the mat but keep your feet up, so your abs stay under tension from the first rep to the last.
How many reverse crunches should I do?
Muscla plans 8–15 reps per set. When every set reaches 15, make the exercise harder rather than doing more reps, for example on an incline bench.
Train it with Muscla
Muscla plans your sets, reps and rest, and sets your next rep target after every session.
Coming to the App Store. Free to start.
Sources
- Escamilla RF, Babb E, DeWitt R, et al. Electromyographic analysis of traditional and nontraditional abdominal exercises: implications for rehabilitation and training. Phys Ther. 2006;86(5):656-671. PubMed
- Lehman GJ, McGill SM. Quantification of the differences in electromyographic activity magnitude between the upper and lower portions of the rectus abdominis muscle during selected trunk exercises. Phys Ther. 2001;81(5):1096-1101. PubMed
- Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis. J Strength Cond Res. 2017;31(12):3508-3523. PubMed