on November 06, 2026
Twisting crunches vs twist sit-ups: see what sets them apart, step-by-step form for each, which one trains your obliques better, the mistakes to avoid and how to make both moves easier or harder at home.
Short answer: A twisting crunch lifts only your head and shoulders, then rotates your ribcage toward the opposite knee, so your abs and obliques stay working the whole time. A twist sit-up curls your whole torso up to sitting before you rotate, which adds a longer range and more hip-flexor work. For focused oblique training, start with twisting crunches; for full-range core strength, add twist sit-ups.
Both moves belong in the same family of rotating ab exercises we cover in our guide to ab twists and twisting exercises. Below, you'll see how to do each one with good form, which muscles each trains, how to make them easier or harder, and how they fit with a Wonder Core home machine.
Twisting crunches vs twist sit-ups: what's the difference?
The difference is range of motion. In a twisting crunch, your shoulder blades lift and your lower back stays on the floor while you rotate. In a twist sit-up, you curl all the way up to a seated position and rotate at the top. Both train your obliques; the sit-up version also brings in your hip flexors.
| Feature | Twisting crunch | Twist sit-up |
|---|---|---|
| How high you lift | Head and shoulders | Whole torso, to sitting |
| Lower back | Stays on the floor | Lifts off the floor |
| Main muscles | Obliques and rectus abdominis | Obliques, rectus abdominis and hip flexors |
| Best for | Focused oblique work, beginners | Full-range core strength |
| Also called | Rotating crunch, cross-body crunch | Twisting sit-up, sit-up with twist |
How do you do a twisting crunch?
Lie on your back with your knees bent, curl your head and shoulders off the floor, then turn your ribcage so one shoulder travels toward the opposite knee. Lower with control and switch sides. Keep your lower back on the floor and let your abs, not your arms, drive the turn.
- Set up: lie on your back with your knees bent and your feet flat on the floor, about hip-width apart.
- Place your hands: cross your arms over your chest, or rest your fingertips lightly beside your temples.
- Curl up: tighten your abs and lift your head and shoulder blades off the floor.
- Rotate: turn your ribcage so your right shoulder moves toward your left knee. Lead with your shoulder, not your elbow.
- Lower and switch: pause for a breath, lower slowly to the floor, then repeat toward the other side.
Mayo Clinic's crunch demonstration gives one cue that matters even more when you add rotation:
"When you're doing abdominal crunches, don't clasp your hands behind your head." — Mayo Clinic, Video: Abdominal crunch
The same video explains that clasped hands put your neck at risk and keep you from isolating your abs, and suggests folding your arms on your chest so your abdominal muscles do the work.
What is a bicycle crunch, and is it a twisting crunch?
Yes. A bicycle crunch is a twisting crunch with a leg movement added: as you rotate one shoulder toward the opposite knee, that knee pulls in while the other leg straightens. Moving your legs while you rotate turns the basic twisting crunch into a more demanding exercise.
How do you do a twist sit-up?
Start in the same position as a crunch, curl your torso all the way up until you're sitting tall, rotate your ribcage to one side, return to center and roll back down slowly. The longer range means more work for your hip flexors, so keep the movement smooth from start to finish.
- Set up: lie on your back with your knees bent and your feet flat. Cross your arms over your chest.
- Curl up: lift your head and shoulders first, then keep curling until your torso is upright.
- Rotate: at the top, turn your ribcage to one side so your opposite elbow points toward your knee.
- Return to center: face forward again before you start lowering.
- Roll down: lower one segment at a time until your shoulders touch the floor, then repeat to the other side.
If curling all the way up is still a work in progress, our beginner core workouts for when you can't do a sit-up build the strength step by step.
Which works your obliques better: twisting crunches or twist sit-ups?
Both train your obliques, because both include trunk rotation. Twisting crunches keep the tension on your abs and obliques the whole time, which makes them the more focused oblique exercise. Twist sit-ups trade some of that focus for a longer range that also works your hip flexors.
Rotation is one of your obliques' core jobs. According to Kenhub's anatomy reference, the external oblique works "in synergy with the contralateral internal abdominal oblique" to rotate your trunk to the opposite side. That's why every turn toward your left knee trains your right external oblique and left internal oblique together.
Research on the twisting crunch family is encouraging. In a study sponsored by the American Council on Exercise (ACE), researchers at San Diego State University used electromyography to compare 13 common ab exercises in 30 healthy adults ages 20 to 45. The bicycle maneuver, a twisting crunch with a leg cycle, ranked first for the rectus abdominis and second for the obliques.
A sit-up adds work from your hip flexors because it bends your trunk at the hip. Kenhub notes that bilateral contraction of the psoas major "produces a flexion of the trunk at the hip joint." Twisting crunches stop before that point, which keeps the spotlight on your abs.
What muscles do twist sit-ups and twisting crunches work?
Both moves train your internal and external obliques, which turn your trunk, and your rectus abdominis, which curls your ribcage toward your pelvis. Twist sit-ups also recruit your hip flexors to lift your torso to sitting. Your deeper core muscles help keep your spine steady throughout.
| Muscle | Its job in the movement |
|---|---|
| External obliques | Rotate your trunk toward the opposite side |
| Internal obliques | Rotate your trunk toward the same side |
| Rectus abdominis | Curls your trunk forward, the "crunch" part of each rep |
| Hip flexors | Lift your torso the rest of the way in a twist sit-up |
Kenhub describes the rectus abdominis simply: it "flexes the trunk anteriorly." Add rotation to that curl and you have a move that trains the front and sides of your waist in a single rep.
What are the most common twisting crunch mistakes?
The most common mistakes are pulling on your neck, turning only your elbows, and rushing the reps with momentum. Each one shifts work away from your obliques. Fix them by keeping your hands light, rotating from your ribcage and slowing the lowering phase, and every rep will do more for your core.
- Pulling on your neck: keep your arms crossed or your fingertips light, and leave space between your chin and chest.
- Turning only your elbows: aim your shoulder, not your elbow, at the opposite knee so your ribcage actually rotates.
- Using momentum: lift and lower at a steady pace and pause briefly at the turn.
- Lifting your feet in a sit-up: keep your heels down; if they pop up, shorten the range until your strength catches up.
- Holding your breath: exhale as you curl and rotate, then inhale as you lower.
How do you make twisting crunches easier or harder?
To make them easier, reduce the range, keep both feet planted and use your arms crossed on your chest. To make them harder, slow the lowering phase, pause at the top of each turn, lift your feet into a bicycle crunch or progress to full twist sit-ups. Change one thing at a time so your form stays clean.
Easier versions:
- Lift only your shoulder blades and rotate a little less.
- Do all your reps to one side, rest, then switch sides.
- Build curl-up strength with spring-assisted sit-ups on an ab machine first.
Harder versions:
- Take 3 seconds to lower on every rep.
- Pause for 1 to 2 seconds at the top of each turn.
- Switch to bicycle crunches, then full twist sit-ups.
- Hold a light weight plate against your chest once your form is consistent.
Once rotation feels strong, add more variety with our guides to Russian twists and standing side twists.
How many twisting crunches should you do?
Train your core at least two days a week and choose a number of reps you can finish with good form on both sides. Mayo Clinic recommends strength training for all major muscle groups at least two times a week, and a single set of 12 to 15 reps is enough to build muscle for most people.
Mayo Clinic puts it this way:
"A single set of 12 to 15 repetitions with the proper weight can build muscle efficiently in most people." — Mayo Clinic, Strength training
For bodyweight twisting crunches, the "proper weight" is the version that makes your last few reps feel challenging while your form stays steady. Pair your ab work with regular cardio, too: the Physical Activity Guidelines for Americans recommend 150 to 300 minutes of moderate aerobic activity a week plus muscle-strengthening activity on at least 2 days.
Can you do twisting crunches on an ab machine?
Yes. A home ab machine can guide both the crunch and the twist. The Wonder Core 2 adds a twisting seat for seated oblique work, and the Wonder Core Smart uses adjustable spring assistance to help you build the curl-up strength behind smooth twist sit-ups. Both fit easily into a home workout space.
Wonder Core 2 ($169.99): its twisting seat enhances oblique and cardio workouts, two springs help you return to the start position, and 8 pulley resistance bands add rowing, curls and raises. It fits users from 5'0" to 6'0" and supports up to 264 lbs. Our first-month Wonder Core 2 routine shows how to combine crunches and the twisting seat.
Wonder Core Smart ($109.99): dual dials set 24 to 48 lbs of spring assistance per side to help you through every sit-up and crunch, so you can build the strength for full-range twist sit-ups at your own pace. It supports up to 264 lbs and comes with guided workouts in the free Wonder Core App. Our Wonder Core Smart review covers every dial setting.
Comparing gym equipment too? See our guide to the best machines for obliques.
Twisting crunch and twist sit-up FAQs
Are twist sit-ups good for you?
Yes. Twist sit-ups train your obliques, rectus abdominis and hip flexors in one full-range movement, which builds the core strength you use to sit up, turn and reach. Do them smoothly with your arms crossed, keep your heels down, and start with twisting crunches if full sit-ups still feel hard.
Do twisting crunches work your obliques?
Yes. Every twisting crunch rotates your trunk, and rotation is a main job of your internal and external obliques. Turning toward your left knee trains your right external oblique and left internal oblique together, so alternating sides trains both sides of your waist evenly.
What's the difference between a bicycle crunch and a twisting crunch?
A bicycle crunch is a twisting crunch with a leg cycle. In a basic twisting crunch your feet stay on the floor; in a bicycle crunch you pull one knee in as you rotate toward it while the other leg straightens. In ACE's study of 13 ab exercises, the bicycle maneuver ranked second for the obliques.
Are twisting crunches safe for your lower back?
Twisting crunches keep your lower back on the floor, which makes them a comfortable way to add rotation for most people. Move slowly, rotate from your ribcage and avoid jerking your neck. If you have a back injury or a health condition, talk to your doctor before starting a new core routine.
How often should you do twisting crunches?
At least two days a week works well for most people. Mayo Clinic recommends strength training for all major muscle groups at least twice a week and resting one full day between sessions for the same muscle group. One set of 12 to 15 good-form reps per side is a practical starting point.
Related reading
- Ab Twists: 5 Twisting Exercises That Train Your Obliques
- Do Russian Twists Build Abs? Muscles Worked, Form & 4 Variations
- Standing Side Twists: How to Do Waist Twists Right
- Can't Do a Sit-Up? Beginner-Friendly Core Workouts
Sources
- American Council on Exercise. American Council on Exercise (ACE)-sponsored Study Reveals Best and Worst Abdominal Exercises.
- Mayo Clinic. Video: Abdominal crunch.
- Mayo Clinic. Strength training: Get stronger, leaner, healthier.
- Kenhub. External abdominal oblique muscle.
- Kenhub. Iliopsoas muscle.
- Kenhub. Rectus abdominis muscle.
- U.S. Department of Health and Human Services. Top 10 Things to Know About the Second Edition of the Physical Activity Guidelines for Americans.
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