Crunches

• Upper abs
• Beginner-friendly
• Reps — 15 reps per set

The crunch is a short, controlled curl of the upper spine that targets the rectus abdominis without pulling on the neck or lower back.

Unlike a full sit-up, only the shoulder blades leave the floor — the lower back stays down, which keeps the work on the abs. Slow reps with a hard squeeze at the top beat fast, bouncy ones every time.

How to do it

1. Lie on your back, knees bent, feet flat on the floor.
2. Place hands behind your head and lift your shoulders toward your knees.
3. Lower back down with control without resting your head.

Breathing: Exhale as you crunch up, inhale as you lower.

Common mistakes

• Squeezing the elbows together in front of your face as you curl up.
• Sliding the heels away from your hips as the reps get harder.
• Lifting the chest toward the ceiling so the spine stays flat instead of rounding.

Form tips

• Leave a fist-sized gap under your chin so the neck never folds toward the chest.
• Keep the lower back on the floor; peeling it up turns this into a sit-up.
• Do not hook the feet under anything, or the hip flexors take over the lift.

Muscles worked

Alternatives with the same focus

• Raised-Leg Crunch
• Toe Touches
• Frog Crunches

Where it appears in the 30-day plan

Programs in the app that schedule this movement:

• Core & Abs
• Upper Abs