Twist Crunch (Legs Up)

How to do the Twist Crunch (Legs Up)

1. 1Lie flat on your back on a mat with your arms crossed over your chest or hands lightly behind your head — do not interlace your fingers.
2. 2Raise both legs until your thighs are perpendicular to the floor and your knees are bent at roughly 90 degrees, shins parallel to the ground.
3. 3Brace your core by drawing your navel gently toward your spine, and press your lower back into the mat.
4. 4Exhale and curl your right shoulder blade off the mat, rotating your right elbow toward your left knee while keeping your left shoulder blade in contact with the floor.
5. 5Hold the top position for a brief pause, feeling the contraction through your right oblique and across your rectus abdominis.
6. 6Inhale as you lower your right shoulder back to the mat under control — do not drop or bounce.
7. 7Exhale and repeat on the opposite side, curling your left shoulder toward your right knee.
8. 8Continue alternating sides for the target number of reps, keeping your legs stable and your lower back pressed into the mat throughout.

Form tips

• Keep the movement in your torso — think 'shoulder to hip' rather than 'elbow to knee' so the obliques, not your neck, drive the rotation.
• Maintain consistent intra-abdominal pressure by bracing before you lift; releasing tension between reps reduces effectiveness and increases lower-back strain.
• Anchor your legs firmly at 90 degrees throughout the set; letting them drift forward or back shifts load away from the target muscles.
• Breathe out on the way up (crunch and rotate) and in on the way down to time your brace with the effort phase.
• Move at a controlled tempo — 1 second up, 1-second hold, 2 seconds down — to maximise time under tension and avoid momentum substituting for muscle work.

Common mistakes

• Pulling the neck forward with interlaced hands — this strains the cervical spine and shifts effort off the abs; keep hands loosely behind the ears or crossed on the chest.
• Letting the legs drop or sway during the crunch — this destabilises the pelvis and reduces oblique activation; hold the legs still at 90 degrees throughout.
• Crunching straight up instead of rotating — a pure forward crunch misses the obliques almost entirely; focus on bringing one shoulder toward the opposite hip.
• Bouncing off the mat between reps — using momentum removes tension from the core at the most important phase of the movement and increases injury risk.
• Holding the breath throughout the set — this raises blood pressure unnecessarily and disrupts core tension management; exhale on each crunch and inhale on the return.

Frequently asked questions