What muscles does the oblique crunch work?

Rectus abdominis and obliques shortening under control, the direct ab work that builds visible thickness. It is classed as a trunk flexion movement and trains the core primarily.

How many sets and reps of oblique crunch should I do?

3 sets of 10 to 20, resting 60 sec between sets. Add load once you can control the tempo for the full set.

Is the oblique crunch good for beginners?

Yes. It is one of the easier movements to learn and hard to get badly wrong, which makes it a good place to build the pattern.

Core · Trunk flexion

Oblique Crunch

The oblique crunch is a bodyweight trunk flexion movement for the core. Here is the setup, the execution, the mistakes worth avoiding, and how to program it.

Equipment

Bodyweight

Trains

Core

Level

Beginner

SHOULDER TO HIPSQUEEZE THE SIDE

Muscles worked

Rectus abdominis and obliques shortening under control, the direct ab work that builds visible thickness.

Set up

1
Set the low back position first, then load it. Momentum is the enemy here.
2
Ribs travel toward the pelvis. That is the whole movement.
3
Slow the eccentric down. The lowering half is where abs actually grow.

How to do it

1
Curl the ribs toward the pelvis and exhale hard at the top.
2
Pause where the abs are fully shortened.
3
Lower for three seconds under full control.
4
Keep tension the whole set rather than resting at the bottom.

Common mistakes

Pulling with the hip flexors
Fix: Think ribs to pelvis, not knees to chest.
Speed reps
Fix: Three seconds down, pause at the top, no bouncing.
Neck doing the work
Fix: Keep a fist of space under the chin and let the abs pull.