Butterfly Reverse Crunch
- Primary muscleAbs
- EquipmentBodyweight
- DifficultyBeginner
- TypeCore · Core flexion
- Secondary muscles
- Hip Flexors, Inner Thighs
- Body part
- Core
- Position
- Lying
- Laterality
- Bilateral (both sides together)
- Category
- Strength
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Pressing the soles of your feet together and letting the knees flare turns a standard reverse crunch into one that also recruits the inner thighs as you curl the legs up. The flared-knee position shortens the lever, so it suits beginners who find a straight-leg lift too demanding on the low back.
How to do the Butterfly Reverse Crunch
- Lie flat on your back with your knees bent and feet flat on the ground.
- Place your hands behind your head with your elbows pointing outwards.
- Engaging your abs, lift your legs off the ground, bringing your knees towards your chest.
- Pause for a moment at the top, then slowly lower your legs back down to the starting position.
- Repeat for the desired number of repetitions.
Tip: Breathe out as you crunch and let the last bit of air leave the lungs at the top of each rep.
Muscles worked
Primary
Abs · Core
The rectus abdominis shortens to bend the spine forward, and each rep should end with the upper abs fully contracted and the ribs pulled down.
Secondary
- Hip Flexors — The hip flexors take over if your feet are anchored and you come up too high; keep the range short to leave them out.
- Inner Thighs
Common mistakes
- Pulling on the neck — hands behind the head should support, not yank; keep the elbows wide and the chin about a fist away from the chest.
- Sitting all the way up — a crunch is a curl of the ribs toward the pelvis, not a sit-up; the lower back should stay on the floor the whole time.
- Cranking out fast reps — momentum does the work if you bounce; lift to a squeeze, hold for a count and lower slowly.
- Never adding load — once bodyweight reps get easy, hold a plate on the chest or use a cable rather than doing sets of 50.
Sets, reps and where it fits
| Goal | Sets × reps | Rest |
|---|---|---|
| Strength | 3 × 8–12 | 60 s |
| Endurance | 2–3 × 15–25 | 45 s |
Crunches close out a session after the heavy work, or they can fill the rest periods between sets of a lift that does not need much bracing. Pair a cable crunch with a cable side bend on the same stack.
Variations and alternatives
Similar exercises
Without bodyweight
Frequently asked questions
What muscles does the Butterfly Reverse Crunch work?
The Butterfly Reverse Crunch primarily works the abs. It also involves the hip flexors and inner thighs, which assist the movement and stabilise the joints.
Is the Butterfly Reverse Crunch good for beginners?
Yes. The Butterfly Reverse Crunch is rated beginner: it uses no equipment beyond your bodyweight and the movement is simple to learn. Start light, focus on the full range of motion and add load once every rep looks the same.
What can I do instead of the Butterfly Reverse Crunch?
If you cannot do the Butterfly Reverse Crunch, try the Crunch, the Frog Crunch or the Negative Crunch. Each of them trains the abs through a similar movement, so you can swap them in without changing the rest of the workout.
How many sets and reps should I do?
It depends on your goal. For the Butterfly Reverse Crunch, a sensible starting point is strength: 3 × 8–12 with 60 s rest; endurance: 2–3 × 15–25 with 45 s rest. Train it at the end of a session or pair it with a lower-body lift as active rest.
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