How to Do a Crunch Properly: Form, Mistakes and Variations
How to do a crunch the right way: hand position, range of motion, breathing and tempo, the most common mistakes that hurt your neck, and harder variations.
By Ayoub Farid · · 3 min read
The crunch is the most famous ab exercise, and possibly the most poorly performed. Good crunches are short, slow and controlled. Here's how.
How to do a crunch
- Lie on your back, knees bent, feet flat, hip-width apart.
- Place your fingertips lightly behind your ears (or cross your arms on your chest).
- Keep a gap the size of a fist between chin and chest.
- Breathe out and curl your ribcage toward your hips, lifting your shoulder blades off the floor.
- Pause at the top for a second.
- Lower slowly, about two seconds.
The range is small. Your lower back stays on the floor. If you come all the way up, that's a sit-up (see sit-ups vs crunches).
Common mistakes
| Mistake | Fix |
|---|---|
| Pulling the head | Fingertips only, or cross arms |
| Chin on chest | Keep the fist gap |
| Bouncing | Pause and slow down |
| Too much range | Only shoulder blades lift |
| Holding breath | Exhale on the way up |
Neck pain? See neck pain during crunches.
Variations
- Easier: arms by your sides, smaller range
- Harder: arms overhead, weighted crunch, decline crunch, cable crunch
- Targeted: cross-body crunch (obliques), reverse crunch (lower abs), toe reach (upper abs)
Sets and reps
Two to three sets of 12–20. When 20 feels easy, make it harder rather than doing 50. See progressive overload for abs.
Are crunches bad for you?
For most healthy people, controlled crunches are safe. Some spine experts recommend limiting high-rep flexion, especially for people with disc issues. If crunches bother you, try curl-ups or an ab workout without crunches.
Muscles worked
The crunch targets the rectus abdominis, especially its upper portion, with help from the obliques. Because the range is short and your lower back stays down, the hip flexors do very little. That's the main difference from a sit-up and why the crunch isolates the abs so well.
The perfect rep, second by second
- 0 s: exhale, brace lightly, ribs down
- 0–1 s: curl the ribcage up; shoulder blades lift
- 1–2 s: hold at the top, squeeze
- 2–4 s: lower slowly, keeping tension
- 4 s: shoulders just touch, start the next rep
At this tempo, 15 reps take a full minute, and you'll feel it far more than 30 quick reps.
A crunch progression ladder
| Level | Variation |
|---|---|
| 1 | Crunch with arms by sides |
| 2 | Crunch with fingertips behind ears |
| 3 | Crunch with arms crossed on chest and 2 s pause |
| 4 | Crunch with arms overhead |
| 5 | Weighted crunch (plate on chest) |
| 6 | Decline or cable crunch |
Move up a level when you can do 3 sets of 20 with perfect form. More in progressive overload for abs.
Where the crunch fits
The crunch is one tool, not a whole routine. Combine it with a lower ab move, an oblique move and a stability move, as in the ab workout at home.
Frequently asked questions
How many crunches a day for a six pack?
No number gives you a six pack. Two or three good sets plus fat loss do.
Should I put my feet under something?
No. Anchoring your feet lets your hip flexors take over.
Crunches or planks?
Both. They train different functions. See best ab exercises.
Do crunches burn belly fat?
No. See the spot reduction myth.