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  7. Seated Open Knee Leg Raise On A Chair

Exercise guide

Seated Open Knee Leg Raise On A Chair

  • Beginner
  • Compound
  • Rep-based
  • Waist

This beginner-friendly core exercise targets the lower abdominals and obliques by utilizing a seated position to isolate the midsection. The wide-knee positioning increases the challenge on the lower core and hip stabilizers compared to a standard leg raise.

Reviewed by the Crucible team · Updated June 2026

Watch the Seated Open Knee Leg Raise On A Chair demonstrationGuided video and your full workout live in the Crucible app.

Muscles worked

Primary

  • Abs
  • Obliques

Secondary

  • Hip flexors

Equipment

  • Body weight

Setup

  1. Sit on the edge of a sturdy chair or flat bench with your feet flat and knees wider than shoulder-width.
  2. Grip the edges of the seat behind your hips to stabilize your upper body.
  3. Lean back slightly (about 20-30 degrees) while keeping your chest open and spine neutral.

How to do it

  1. Exhale and pull your knees up toward your chest while maintaining the wide, 'open' knee position.
  2. Squeeze your abdominals at the top of the movement for a one-second pause to maximize peak contraction.
  3. Inhale as you slowly lower your legs back down toward the floor over a two-second count.
  4. Stop just before your feet touch the ground to maintain constant tension on the abdominal muscles.

Form checklist

  • Keep your shoulders down and away from your ears to avoid neck tension.
  • Maintain the wide knee angle throughout the entire range of motion.
  • Avoid rounding your lower back excessively as you lift your legs.
  • Ensure the movement is driven by your core, not by swinging your legs.
  • Keep your core braced as if you are about to be poked in the stomach.

Pro tips

  • Focus on the 'posterior pelvic tilt'—imagine pulling your belly button toward your spine to engage the deep transverse abdominis.
  • Press your hands firmly into the chair to create 'radiating tension,' which helps stabilize your torso and allows for a stronger leg lift.

Make it harder

  • Perform the movement with a slow 4-second eccentric (lowering) phase to increase time under tension.
  • Hold a light dumbbell between your feet or wear ankle weights to increase the resistance.

Frequently asked

What muscles does the seated open knee leg raise on a chair work?
The seated open knee leg raise on a chair primarily targets the abs and obliques, and also works the hip flexors as secondary muscles.
What equipment do you need for the seated open knee leg raise on a chair?
The seated open knee leg raise on a chair requires no equipment — just your body weight.
Is the seated open knee leg raise on a chair good for beginners?
Yes. The seated open knee leg raise on a chair is a beginner-friendly movement and a strong foundation to build on.

Related exercises

  • 3/4 Sit-UpBeginner · abs and obliques
  • 45 Degree Bicycle Twisting CrunchIntermediate · abs and obliques
  • 45 Degree Lean Back Alternate Knee RaiseBeginner · abs and obliques
  • 45 Degrees Arms PlankIntermediate · abs, deltoids, obliques, and pectorals

Train this with a plan, not guesswork

Crucible builds the seated open knee leg raise on a chair into a precise program around your body, equipment, location, and time.

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