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  3. Exercises
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  5. Core & Abs
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  7. Sitting Floor Crunch Alternating Knee Raise to Toe Touch

Exercise guide

Sitting Floor Crunch Alternating Knee Raise to Toe Touch

  • Intermediate
  • Compound
  • Rep-based
  • Upper legs
  • Waist

This intermediate core exercise targets the entire abdominal wall and obliques while utilizing the quadriceps to stabilize and lift the legs. It improves functional coordination and rotational strength by combining a seated crunch with a cross-body reach.

Reviewed by the Crucible Fit team · Updated June 2026

Watch the Sitting Floor Crunch Alternating Knee Raise to Toe Touch demonstrationVideo and instructions for every movement are in the Crucible Fit app.

Muscles worked

Primary

  • Abs
  • Obliques

Secondary

  • Hip flexors

Equipment

  • Body weight

Setup

  1. Sit on the floor or the edge of a flat bench with your knees bent and feet flat.
  2. Lean your torso back to a 45-degree angle, supporting your weight with your hands placed slightly behind your hips.
  3. Engage your core and lift your feet 2-3 inches off the ground to find your balance point on your sit-bones.

How to do it

  1. Exhale as you pull one knee toward your chest while simultaneously crunching your torso forward and reaching the opposite hand toward that toe.
  2. Inhale as you return to the starting 'V' position with control, keeping your feet hovering off the floor.
  3. Perform the same movement on the opposite side, alternating legs and arms in a fluid, rhythmic motion.
  4. Maintain a 2-1-2 tempo (2 seconds to crunch, 1-second squeeze, 2 seconds to return).

Form checklist

  • Keep your chest open and avoid excessive rounding of the upper back.
  • Ensure the movement is driven by the abdominals rather than just the hip flexors.
  • Keep your neck neutral and avoid tucking your chin into your chest.
  • Maintain a slight hover with the feet throughout the entire set to keep constant tension on the abs.
  • Focus on the rotation of the torso to fully engage the obliques.

Pro tips

  • Think about bringing your ribcage toward your opposite hip to maximize the contraction of the obliques.
  • Slow down the eccentric (lowering) phase to increase time under tension and prevent momentum from taking over.

Make it harder

  • Perform the movement with your hands behind your head instead of on the floor to remove the stability support.
  • Wear ankle weights to increase the load on the lower abdominals and quadriceps.

Frequently asked

What muscles does the sitting floor crunch alternating knee raise to toe touch work?
The sitting floor crunch alternating knee raise to toe touch primarily targets the abs and obliques, and also works the hip flexors as secondary muscles.
What equipment do you need for the sitting floor crunch alternating knee raise to toe touch?
The sitting floor crunch alternating knee raise to toe touch requires no equipment — just your body weight.
Is the sitting floor crunch alternating knee raise to toe touch good for beginners?
The sitting floor crunch alternating knee raise to toe touch is rated intermediate. Build a base with simpler variations first, then progress to it with light load and strict form.

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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