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  3. Exercises
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  5. Core & Abs
  6. /
  7. Twisting Knee-Up

Exercise guide

Twisting Knee-Up

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

The Twisting Knee-Up is a dynamic core exercise that targets the rectus abdominis and obliques by combining hip flexion with trunk rotation. It improves rotational stability and functional core strength while engaging the hip flexors and quadriceps.

Reviewed by the Crucible Fit team · Updated June 2026

Watch the Twisting Knee-Up demonstrationVideo and instructions for every movement are in the Crucible Fit app.

Muscles worked

Primary

  • Abs
  • Obliques

Secondary

  • Glutes
  • Hip flexors

Equipment

  • Body weight

Setup

  1. Stand tall with your feet hip-width apart and your core engaged.
  2. Place your hands lightly behind your head with elbows flared out, or hold them at chest height.
  3. Distribute your weight evenly across both feet and maintain a neutral spine.

How to do it

  1. Exhale as you lift your right knee toward your chest while rotating your torso to bring your left elbow toward the rising knee.
  2. Contract your obliques at the top of the movement, aiming to bring the shoulder across the body rather than just the elbow.
  3. Inhale as you lower your leg and return your torso to the center with control.
  4. Repeat the movement on the opposite side, alternating legs for the duration of the set.

Form checklist

  • Rotate from the ribcage and waist, not just the shoulders.
  • Keep your chest open and avoid pulling on your neck with your hands.
  • Maintain a slight bend in the standing leg for better balance.
  • Drive the knee up as high as possible to maximize lower abdominal engagement.

Pro tips

  • Focus on the 'mind-muscle connection' by imagining your opposite rib moving toward your hip bone.
  • Pause for a split second at the peak of the contraction to maximize oblique recruitment.

Make it harder

  • Increase the tempo to a 'sprinter' pace to add a cardiovascular element while maintaining form.
  • Perform the movement with a slow 3-second eccentric (lowering) phase to increase time under tension.

Frequently asked

What muscles does the twisting knee-up work?
The twisting knee-up primarily targets the abs and obliques, and also works the glutes and hip flexors as secondary muscles.
What equipment do you need for the twisting knee-up?
The twisting knee-up requires no equipment — just your body weight.
Is the twisting knee-up good for beginners?
The twisting knee-up 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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