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. Shoulders
  6. /
  7. Diagonal Reach On Chair

Exercise guide

Diagonal Reach On Chair

  • Intermediate
  • Compound
  • Rep-based
  • Shoulders
  • Upper arms
  • Waist

This seated core exercise targets the obliques and rectus abdominis through controlled rotation and hip flexion, making it an excellent low-impact option for improving spinal mobility and core stability.

Reviewed by the Crucible Fit team · Updated June 2026

Watch the Diagonal Reach On Chair demonstrationVideo and instructions for every movement are in the Crucible Fit app.

Muscles worked

Primary

  • Abs
  • Obliques

Secondary

  • Serratus anterior
  • Trapezius

Equipment

  • Body weight

Setup

  1. Sit upright on the front edge of a stable chair with your feet flat on the floor, hip-width apart.
  2. Engage your core and maintain a tall, neutral spine with your chest lifted.
  3. Extend your arms out to your sides at shoulder height or place your hands lightly behind your ears.

How to do it

  1. Exhale as you rotate your torso and reach one hand diagonally across your body toward the opposite knee.
  2. Simultaneously lift that opposite knee toward your chest to meet your hand, focusing on the crunch in your side-abs.
  3. Inhale as you slowly return to the starting upright position with a controlled tempo.
  4. Repeat the movement on the opposite side, alternating sides for each repetition.

Form checklist

  • Keep your spine long and avoid rounding your lower back as you reach.
  • Initiate the rotation from your midsection rather than just moving your arms.
  • Keep your planted foot firmly on the ground to maintain balance.
  • Ensure your hips stay glued to the chair throughout the entire movement.

Pro tips

  • Think about bringing your ribcage toward your opposite hip to maximize the contraction of the internal and external obliques.
  • Pause for one second at the peak of the reach to emphasize the mind-muscle connection with your core.

Make it harder

  • Straighten your leg as you lift it to increase the lever length and resistance on the lower abs.
  • Hold a light weight or water bottle in your hands to add resistance to the rotational phase.

Frequently asked

What muscles does the diagonal reach on chair work?
The diagonal reach on chair primarily targets the abs and obliques, and also works the serratus anterior and trapezius as secondary muscles.
What equipment do you need for the diagonal reach on chair?
The diagonal reach on chair requires no equipment — just your body weight.
Is the diagonal reach on chair good for beginners?
The diagonal reach on chair 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
  • Alternate Knee Raise Side ReachBeginner · abs, deltoids, and obliques
  • Ardha Matsyendrasana Yoga PoseIntermediate · abs, glutes, obliques, and trapezius
  • Back Steps PlankIntermediate · 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