Crunch

Crunch

The crunch is the basic exercise for isolating the upper rectus abdominis.

Muscles Involved

• Rectus abdominis (upper portion) : primary target
• Obliques : assist the flexion

Step-by-Step Instructions

Step 1 — Position

Lying on back, knees bent, feet flat on floor. Hands behind head without pulling the neck.

Step 2 — Flexion

Curl shoulders toward pelvis contracting the abs. Lower back stays on the floor.

Step 3 — Contraction

Hold the contraction 1-2 seconds at top.

Step 4 — Return

Lower controlled without fully resting the head.

Sets and Reps

3 sets of 15-25 reps.

Common Mistakes

• Pulling the neck : light hands behind head
• Sitting all the way up : it's a curl, not a sit-up
• Lower back lifting : keep it pressed down

Safety Tips

Never pull the neck. Range is short: only shoulder blades leave the floor. Perfect for beginners.

Variations

• Swiss ball crunch : increased range
• Weighted crunch : plate on chest
• Cable crunch : constant resistance

Who Is This Exercise For?

Beginners. The fundamental exercise to start abdominal work.