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  3. Exercises
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  5. Core & Abs
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  7. Straight Legs Sit Up Toe Tap

Exercise guide

Straight Legs Sit Up Toe Tap

  • Beginner
  • Compound
  • Rep-based
  • Waist

This exercise combines a full sit-up with a cross-body reach to target the rectus abdominis and obliques while improving spinal mobility and hamstring flexibility.

Reviewed by the Crucible Fit team · Updated June 2026

Watch the Straight Legs Sit Up Toe Tap 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. Lie flat on your back on a mat with your legs fully extended and feet hip-width apart.
  2. Extend your arms straight overhead on the floor, palms facing up.
  3. Engage your core by pressing your lower back firmly into the mat to eliminate any arch.

How to do it

  1. Exhale as you peel your spine off the floor one vertebra at a time, sitting up while reaching your right hand toward your left toes.
  2. Rotate your torso at the top of the movement to ensure your hand makes contact with or reaches toward the opposite foot.
  3. Inhale as you slowly roll your spine back down to the starting position with control, avoiding a 'thud' on the mat.
  4. Repeat the movement on the opposite side, reaching your left hand toward your right toes, and continue alternating.

Form checklist

  • Keep your legs locked straight and your heels glued to the floor throughout the entire rep.
  • Avoid using arm momentum or 'swinging' yourself up; use your abs to initiate the lift.
  • Maintain a slight tuck in your chin to protect your neck as you rise.
  • Ensure the rotation happens in the mid-back (thoracic spine) rather than just reaching with the shoulder.

Pro tips

  • Focus on the 'articulation' of the spine—imagine peeling your back off the floor like a piece of tape to maximize muscle fiber recruitment.
  • Squeeze your quads and flex your toes toward your shins to create a stable anchor for your lower body.

Make it harder

  • Hold a light dumbbell or medicine ball in your hands to add resistance to the sit-up and rotation.
  • Slow down the eccentric (lowering) phase to a 4-second count to increase time under tension.

Frequently asked

What muscles does the straight legs sit up toe tap work?
The straight legs sit up toe tap primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.
What equipment do you need for the straight legs sit up toe tap?
The straight legs sit up toe tap requires no equipment — just your body weight.
Is the straight legs sit up toe tap good for beginners?
Yes. The straight legs sit up toe tap is a beginner-friendly movement and a strong foundation to build on.

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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