Exercise guide
Oblique Crunch
- Beginner
- Compound
- Rep-based
- Waist
This exercise isolates the internal and external obliques by combining spinal flexion with rotation, using a bench to stabilize the pelvis and eliminate hip flexor momentum.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back on the floor with a flat bench positioned at your feet.
- Place your lower legs on the bench so your hips and knees are both bent at 90-degree angles.
- Place your fingertips lightly behind your ears with elbows flared out, or cross your arms over your chest.
How to do it
- Exhale as you lift one shoulder off the floor, rotating your torso to move that shoulder toward the opposite knee.
- Contract your obliques hard at the top of the movement, ensuring your lower back stays pressed into the floor.
- Inhale as you slowly lower your shoulder back to the starting position using a controlled 2-second tempo.
- Perform all repetitions on one side to maintain unilateral tension before switching to the other side.
Form checklist
- Keep your lower back glued to the floor to protect the spine and isolate the core.
- Lead the movement with your shoulder rather than pulling on your head or neck with your hands.
- Maintain a small gap between your chin and chest throughout the entire set.
- Keep your legs and hips still on the bench; do not use them to generate momentum.
Pro tips
- Focus on bringing your armpit toward the opposite hip rather than just touching your elbow to your knee for deeper muscle fiber recruitment.
- Perform a forceful 'mini-exhale' at the peak of the contraction to engage the deep transverse abdominis.
Make it harder
- Hold the peak contraction for 2-3 seconds on every repetition to increase time under tension.
- Hold a light weight plate or medicine ball against your chest to add external resistance.
Frequently asked
- What muscles does the oblique crunch work?
- The oblique crunch primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.
- What equipment do you need for the oblique crunch?
- The oblique crunch requires no equipment — just your body weight.
- Is the oblique crunch good for beginners?
- Yes. The oblique crunch is a beginner-friendly movement and a strong foundation to build on.