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  1. Home
  2. /
  3. Exercises
  4. /
  5. Core & Abs
  6. /
  7. Seated Lean Back Open And Close On A Chair

Exercise guide

Seated Lean Back Open And Close On A Chair

  • Beginner
  • Compound
  • Rep-based
  • Lower legs
  • Waist

This beginner-friendly core exercise targets the lower abdominals and hip flexors while utilizing a lean-back position to maintain constant tension on the rectus abdominis. The horizontal leg movement further engages the obliques and inner thighs for improved pelvic stability.

Reviewed by the Crucible Fit team · Updated June 2026

Watch the Seated Lean Back Open And Close On A Chair demonstrationVideo and instructions for every movement are in the Crucible Fit app.

Muscles worked

Primary

  • Abs
  • Obliques

Secondary

  • Glutes
  • Hamstrings

Equipment

  • Body weight

Setup

  1. Sit on the front edge of a sturdy chair or flat bench with your feet together on the floor.
  2. Grip the sides of the seat just behind your hips to provide stability and support.
  3. Lean your torso back to approximately a 45-degree angle, keeping your spine straight and chest lifted.
  4. Lift your feet off the floor and extend your legs straight out in front of you at hip height.

How to do it

  1. Inhale and brace your core as you slowly spread your legs apart as wide as possible in a controlled 'V' shape.
  2. Exhale and squeeze your inner thighs to bring your legs back together until your feet touch or cross slightly.
  3. Maintain a steady tempo of 2 seconds to open and 2 seconds to close, keeping your legs elevated the entire time.
  4. Continue the alternating opening and closing motion while keeping your torso completely still.

Form checklist

  • Keep your lower back flat or slightly arched; do not allow your spine to round forward.
  • Ensure your shoulders stay down and away from your ears to avoid neck tension.
  • Keep your legs as straight as possible to maximize the lever length and core demand.
  • Maintain a consistent lean-back angle throughout the entire set.

Pro tips

  • Focus on pulling your belly button toward your spine to engage the deep transverse abdominis for better stability.
  • Point your toes and squeeze your quads to keep your legs rigid, which helps transfer the load directly to your lower abs.
  • Pause for one second at the widest point of the 'open' phase to challenge your obliques and hip stabilizers.

Make it harder

  • Perform the movement with your hands behind your head or reaching forward instead of holding the chair for support.
  • Slow the tempo down significantly or add small ankle weights to increase the resistance on the hip flexors and abs.

Frequently asked

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

Related exercises

  • 45 Degrees Arms PlankIntermediate · abs, deltoids, obliques, and pectorals
  • 90 To 90Beginner · abs, glutes, obliques, and quadriceps
  • 90 To 90 SwitchIntermediate · abs, glutes, obliques, and quadriceps
  • Air BikeIntermediate · abs and obliques

Train it with Crucible Fit.

Every movement in this library is in the app with video and instructions, ready for your own sessions on the days between Crucibles. Your first Crucible is on us.

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