Crunch (arms straight)

How to do the Crunch (arms straight)

1. 1Lie on your back on a mat with your knees bent and feet flat on the floor, hip-width apart.
2. 2Extend your arms straight and reach them past your head so your biceps frame your ears, keeping a small natural arch in your lower back.
3. 3Brace your core and exhale as you curl your shoulders and upper back off the floor, sweeping your straight arms forward toward your knees.
4. 4Lift until your shoulder blades clear the mat, keeping your arms in line with your torso rather than swinging them for momentum.
5. 5Pause briefly at the top and squeeze your abs hard.
6. 6Inhale and lower your shoulders back down under control, returning your arms overhead to the start.
7. 7Repeat for your target reps, keeping your lower back in contact with the floor throughout.

Form tips

• Move your arms and torso as one unit — the straight arms add resistance only if you don't throw them for momentum.
• Curl your spine segment by segment instead of jerking up in one rigid piece, so the work stays on the abs.
• Exhale on the way up and draw your belly button toward your spine to deepen the contraction.
• Keep your chin a fist's width from your chest to protect your neck and avoid pulling your head forward.
• Slow the lowering phase to keep tension on the rectus abdominis for the full range.

Common mistakes

• Swinging the straight arms to generate momentum, which lets your hip flexors and inertia do the work instead of your abs.
• Pulling the head and neck forward to reach higher, which strains the cervical spine and adds no abdominal work.
• Arching the lower back off the floor at the bottom, which shifts load to the spine and reduces ab tension.
• Yanking up with a flat, rigid torso rather than curling the spine, so the abs never fully shorten.

Frequently asked questions