Skip to content
Crucible Fit
  • The Crucible
  • The Week
  • Programs
  • Train Your Way
  • Pricing
Get Crucible
  • The Crucible
  • The Week
  • Programs
  • Train Your Way
  • Apple Watch
  • Pricing
  • FAQ
  • Training Guides
Get Crucible
Crucible Fit

A daily functional fitness test for iPhone, Apple Watch and Android. Stations, reps and the Crux, sized to your readiness and your kit.

Download on the App StoreGet it on Google Play

Crucible Fit

  • The Crucible
  • The Week
  • Programs
  • Train Your Way
  • Apple Watch
  • Pricing

Explore

  • Training Guides
  • Exercise Library
  • FAQ
  • Press
  • Support

Legal

  • Terms and Conditions
  • Privacy Policy
  • Consumer Health Data Notice

CRUCIBLE FIT™ and Crux by Crucible Fit are trademarks of Crucible Fit, LLC.

© 2026 Crucible Fit, LLC. All rights reserved. Apple, the Apple logo, iPhone and Apple Watch are trademarks of Apple Inc., registered in the U.S. and other countries. App Store is a service mark of Apple Inc. Google Play and the Google Play logo are trademarks of Google LLC.

  1. Home
  2. /
  3. Exercises
  4. /
  5. Arms
  6. /
  7. Sitting Floor Alternating Crunch Knee Raise and Toe Touch

Exercise guide

Sitting Floor Alternating Crunch Knee Raise and Toe Touch

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

This compound core exercise targets the rectus abdominis and obliques by combining a seated knee tuck with a rotational crunch. It challenges balance and coordination while building functional rotational strength and stability.

Reviewed by the Crucible Fit team · Updated June 2026

Watch the Sitting Floor Alternating Crunch Knee Raise and Toe Touch 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. Sit on the floor with your knees bent and feet flat, leaning your torso back at a 45-degree angle to engage the core.
  2. Lift your feet 2-3 inches off the ground, balancing on your sit bones in a 'V' position.
  3. Extend your arms out to the sides to form a 'T' shape or place your fingertips lightly behind your ears.

How to do it

  1. Exhale as you pull your right knee toward your chest while rotating your torso to bring your left shoulder toward the incoming knee.
  2. Simultaneously extend your left leg straight out, keeping it hovering just above the floor.
  3. Inhale as you return to the starting balanced position with both knees slightly tucked toward the chest.
  4. Repeat the movement on the opposite side, pulling the left knee in and rotating the right shoulder toward it in a fluid, alternating motion.

Form checklist

  • Maintain a neutral spine; do not allow your lower back to excessively round or collapse.
  • Keep your chest lifted and shoulders pulled back to avoid hunching.
  • Ensure the rotation originates from the torso and obliques, not just the arms or neck.
  • Keep your feet off the floor for the entire duration of the set to maintain constant tension.

Pro tips

  • Focus on bringing the shoulder toward the opposite hip rather than just the elbow to the knee for deeper oblique recruitment.
  • Pause for one second at the peak of the contraction to emphasize the mind-muscle connection with the abdominal wall.

Make it harder

  • Slow the tempo to a 3-second count for both the extension and the crunch phases to eliminate momentum.
  • Hold a light medicine ball or weight plate between your hands to increase the rotational resistance.

Frequently asked

What muscles does the sitting floor alternating crunch knee raise and toe touch work?
The sitting floor alternating crunch knee raise and toe touch primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.
What equipment do you need for the sitting floor alternating crunch knee raise and toe touch?
The sitting floor alternating crunch knee raise and toe touch requires no equipment — just your body weight.
Is the sitting floor alternating crunch knee raise and toe touch good for beginners?
The sitting floor alternating crunch knee raise and 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
  • Ardha Matsyendrasana Yoga PoseIntermediate · abs, glutes, obliques, and trapezius
  • Back Steps PlankIntermediate · abs, lats, and obliques
  • Barbell Hip Twist RolloutIntermediate · abs, lats, 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.

Download on the App StoreGet it on Google Play

See how a Crucible works