Butterfly Sit-Up — how to, muscles worked, alternatives

How to do the Butterfly Sit-Up

Soles of your feet together, knees open, fingertips behind head.
Lie back under control until your shoulders touch the floor.
Exhale and sit up until your torso is near upright.
Lower slowly back to the floor, feet staying together.

Full technique — 7 steps

Sit on a mat, bend your knees, and press the soles of your feet together with your knees falling open to the sides.
Place a small pad or folded mat under your lower back if you want support through the full range.
Put your fingertips lightly behind your head with your elbows out to the sides.
Lie back under control until your shoulders touch the floor.
Exhale and sit up by bringing your ribs toward your hips, leading with your chest rather than your hands.
Continue rising until your torso is near upright over your hips.
Lower back down under control and start the next rep from the floor.

Common mistakes

Pulling the head with hands
Swinging arms for momentum
Dropping back without control
Feet sliding apart during the rep
Stopping at a crunch

Form cues

Exhale on the way up
Lift with abs first
Hands stay by head
Keep chin neutral

Substitutes by equipment

Same muscles, same movement — pick the version you have the gear for.

Where to start and where to go next

Same muscles, same movement. Too hard for now — step down; once it gets easy — step up.

Easier Ab Wheel Straight Arm Crunch 15% of bodyweight
Easier Reverse Crunch 25% of bodyweight
This exercise Butterfly Sit-Up 30% of bodyweight
Harder Ab Wheel Half Rollout 40% of bodyweight
Harder Ab Wheel Knee Tuck 60% of bodyweight

Too hard for now? Start with the Reverse Crunch.

Quick answers

What muscles does the Butterfly Sit-Up work?

Primary: Abs 9/10. Also works: Obliques 5/10.

When should I do the Butterfly Sit-Up in a workout?

Finisher. Goes last, once the heavy work is done. ≈ 5 min with rest.

How many sets and reps of the Butterfly Sit-Up?

Strength: 3–4 sets of 8–12 reps, rest 1 min 15 s, 2 reps in reserve. Muscle growth: 3–4 sets of 12–20 reps, rest 1 min, 2–3 reps in reserve. Endurance: 2–3 sets of 20–30 reps, rest 45 s, 3–4 reps in reserve.

What can I do instead of the Butterfly Sit-Up?

Dumbbells: Dumbbell Decline Sit-Up, Dumbbell Straight Arm Crunch. Resistance bands: Lying Resistance Band Crunch, Lying Resistance Band Knee Tuck. Medicine ball: Medicine Ball Toe Touch Crunch, Medicine Ball Straight Arm Crunch. Suspension trainer: Suspension Trainer Hanging Knee Raise, Suspension Trainer Hanging Leg Raise.