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  3. Exercises
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  5. Core & Abs
  6. /
  7. Extra Decline Sit Up

Exercise guide

Extra Decline Sit Up

  • Intermediate
  • Compound
  • Rep-based
  • Waist

The Extra Decline Sit Up targets the entire abdominal wall and obliques by increasing the range of motion and gravitational resistance compared to a standard sit-up. This variation emphasizes the deep eccentric stretch and a powerful concentric contraction for maximum core development.

Reviewed by the Crucible Fit team · Updated June 2026

Watch the Extra Decline Sit Up demonstrationVideo and instructions for every movement are in the Crucible Fit app.

Muscles worked

Primary

  • Abs
  • Obliques

Secondary

  • Erector spinae

Equipment

  • Body weight

Setup

  1. Adjust the decline bench to a steep angle and secure your ankles firmly under the padded rollers.
  2. Sit upright on the bench with your knees bent and your hips tucked forward.
  3. Place your hands lightly behind your ears or cross them over your chest to avoid pulling on your neck.

How to do it

  1. Inhale and slowly lower your torso backward until your body is parallel to the floor, maintaining constant tension in your core.
  2. Exhale and initiate the upward movement by curling your chin toward your chest and 'peeling' your spine off the bench one vertebra at a time.
  3. Continue rising until your torso is perpendicular to the floor, focusing on the contraction in the rectus abdominis.
  4. Lower yourself back down with a controlled 3-second eccentric phase, stopping just before your shoulder blades touch the bench.

Form checklist

  • Keep your lower back slightly rounded to ensure the abs are doing the work rather than the hip flexors.
  • Avoid resting your weight at the bottom of the movement to maintain constant mechanical tension.
  • Ensure your feet stay locked under the pads and do not lift as you rise.
  • Keep your elbows wide and chin tucked to prevent straining the cervical spine.

Pro tips

  • Focus on the 'rib-to-pelvis' connection, imagining you are folding your torso in half to maximize abdominal shortening.
  • Pause for a full second at the top of the movement to emphasize the peak contraction of the upper abs.

Make it harder

  • Hold a weight plate or medicine ball against your chest or extended overhead to increase the lever arm.
  • Add a slight torso rotation at the top of each rep to increase oblique involvement.

Frequently asked

What muscles does the extra decline sit up work?
The extra decline sit up primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.
What equipment do you need for the extra decline sit up?
The extra decline sit up requires no equipment — just your body weight.
Is the extra decline sit up good for beginners?
The extra decline sit up is rated intermediate. Build a base with simpler variations first, then progress to it with light load and strict form.

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 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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