Exercise guide · Core & Abs

Crunch

The crunch trains your abs with a small spinal flexion. You lie on your back, lift your shoulder blades off the floor, and lower under control—focused on your abdominal muscles rather than pulling with your neck.

Targets: Core
Equipment: Bodyweight
Type: Isolation

Step by step

How to do the Crunch

Lie on your back on a mat with your knees bent and your feet flat on the floor hip-width apart.
Place your fingertips lightly behind your ears or cross your arms over your chest—don't interlace your fingers behind your head.
Brace your core and press your lower back gently toward the floor.
Exhale and curl your rib cage toward your pelvis until your shoulder blades lift off the mat.
Pause briefly at the top, then inhale and lower under control until your shoulder blades touch down.
Repeat for your reps without using momentum from your arms or hips.

Form cues

Think ribs to hips, not elbows to knees
Keep your chin a fist-width away from your chest
Keep light contact between your lower back and the mat at the start
Use a short range—your hips stay down

Common mistakes

Pulling on your head with your hands
Jerking up with momentum on every rep
Letting your feet slide or your hips pop up off the floor
Using a full sit-up range when you only want an ab crunch

Muscles worked

Primary

Core

Secondary

None significant

Safety: Keep your neck relaxed and move slowly. Stop if you feel neck strain—reduce your range or support your head lightly with a towel.

Alternatives

Similar core & abs exercises

See all core & abs exercises · Browse the full exercise library