Exercise guide
Frog Crunch
- Beginner
- Compound
- Rep-based
- Waist
The Frog Crunch is a core-strengthening exercise that targets the rectus abdominis and obliques while minimizing hip flexor involvement by placing the legs in a butterfly position. This variation emphasizes the lower abdominal region and improves core stability through a unique range of motion.
Reviewed by the Crucible team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back on a mat with your legs extended.
- Bend your knees and bring the soles of your feet together, allowing your knees to fall open to the sides in a butterfly position.
- Place your fingertips lightly behind your ears or cross your arms over your chest.
How to do it
- Exhale and contract your abdominals to lift your head, neck, and shoulder blades off the floor.
- Focus on pulling your ribcage toward your pelvis while keeping your lower back pressed firmly into the mat.
- Inhale as you slowly lower your upper body back to the starting position with a controlled 2-second tempo.
Form checklist
- Keep your lower back glued to the floor throughout the movement.
- Avoid pulling on your neck with your hands; use your core to lift.
- Maintain the butterfly leg position to keep the hip flexors relaxed.
- Keep a small space between your chin and your chest.
Pro tips
- Pause for one second at the peak of the contraction to maximize muscle fiber recruitment.
- Visualize your belly button pulling down toward your spine as you lift to ensure deep core engagement.
Make it harder
- Lift your feet 2-3 inches off the ground while performing the crunch to increase lower abdominal tension.
- Perform the movement with your arms extended overhead to increase the lever length and resistance.
Frequently asked
- What muscles does the frog crunch work?
- The frog crunch primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.
- What equipment do you need for the frog crunch?
- The frog crunch requires no equipment — just your body weight.
- Is the frog crunch good for beginners?
- Yes. The frog crunch is a beginner-friendly movement and a strong foundation to build on.