Starfish Crunch
The starfish crunch is a bodyweight exercise targeting the abdominal muscles through a diagonal cross-body crunch from an X-shaped lying position. The movement develops full abdominal and oblique engagement with a wide range of motion.
How to do it
- Lie flat on your back with your arms and legs extended outward in an X shape.
- Simultaneously lift your right arm and left leg, crunching your torso to bring them toward each other.
- Touch or reach toward your foot at the top of the movement.
- Lower back to the starting X position.
- Repeat on the opposite side, lifting your left arm and right leg.
- Continue alternating for the desired number of repetitions.
Form cues
- Start lying flat in a wide X shape.
- Exhale as you lift your opposite arm and leg together.
- Keep your lower back gently pressed into the floor.
- Reach toward your foot, then lower with control.
Breathing: Exhale as you crunch upward and reach toward your foot, and inhale as you lower back down to the starting X position.
Common mistakes
- Rushing the movement causes momentum to take over instead of engaging your abs.
- Lifting the lower back off the floor can strain your spine, so keep your core braced.
- Bending the knee too much during the lift reduces the challenge on your obliques.
Muscles worked
Primary: abs. Secondary: obliques, hip flexors, shoulders.
Suggested sets & reps
Get fitter
3 sets × 10–14 reps per side, rest 60 seconds
Lose weight
3 sets × 12–16 reps per side, rest 45 seconds
Build muscle
3–4 sets × 8–12 reps per side, rest 60 seconds
Easier, harder & alternatives
Make it easier
Make it harder
Alternatives
Take care if…
- If you feel lower back discomfort, ease off the range of motion or choose a gentler core exercise.
General educational guidance, not medical advice. Stop on sharp pain and check with a qualified professional if unsure.
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Start free →Frequently asked questions
What should I do if I feel this in my lower back?
Press your lower back gently into the floor before you start, and reduce your range of motion if needed.
How often can I do starfish crunches?
You can include them 2 to 3 times per week as part of your core routine, allowing a day of rest in between.
Do I need to touch my toes?
Not necessarily. Just reach as far as comfortable while keeping your form clean and your torso stable.