Exercise guide
Groin Crunch
- Beginner
- Isolation
- Rep-based
- Waist
The Groin Crunch, also known as the Butterfly Crunch, isolates the abdominal muscles by placing the legs in a diamond shape, which effectively reduces hip flexor recruitment. This position ensures the core performs the majority of the work while providing a slight stretch to the adductors.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back on a comfortable surface or yoga mat.
- Bend your knees and bring the soles of your feet together, allowing your knees to fall open to the sides in a diamond shape.
- Place your fingertips lightly behind your ears or cross your arms over your chest.
How to do it
- Exhale and contract your abs to lift your head and shoulder blades off the floor.
- Curl your upper body toward your pelvis, keeping your lower back pressed firmly into the mat.
- Inhale as you slowly lower your shoulders back to the floor with a controlled 2-second tempo.
- Repeat for the desired number of repetitions without letting your core fully relax between reps.
Form checklist
- Keep your chin tucked slightly to avoid pulling on your neck.
- Ensure your knees stay open and relaxed to keep the hip flexors disengaged.
- Press your lower back into the floor throughout the entire range of motion.
- Avoid using momentum or swinging your arms to lift your torso.
Pro tips
- Focus on the mind-muscle connection by visualizing your ribcage sliding down toward your hip bones.
- Squeeze your glutes slightly to help stabilize the pelvis and further deactivate the hip flexors.
- Pause for a split second at the top of the movement to maximize peak contraction.
Make it harder
- Perform the movement with your arms extended straight overhead to increase the lever length and resistance.
- Hold a light weight plate or medicine ball against your chest.
Frequently asked
- What muscles does the groin crunch work?
- The groin crunch primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.
- What equipment do you need for the groin crunch?
- The groin crunch requires no equipment — just your body weight.
- Is the groin crunch good for beginners?
- Yes. The groin crunch is a beginner-friendly movement and a strong foundation to build on.