Crunch
The crunch is a foundational bodyweight core exercise that targets the rectus abdominis. By lifting the shoulder blades off the floor with the knees bent, the movement isolates the abs through spinal flexion, forming the basis of most abdominal training routines.
How to do it
- Lie flat on your back with your knees bent and feet flat on the floor.
- Place your hands behind your head with your elbows pointing outward.
- Engage your abs and lift your shoulder blades off the floor.
- Pause at the top of the movement, then slowly lower back to the starting position.
- Repeat for the desired number of repetitions.
Form cues
- Keep your lower back pressed into the floor.
- Look toward your knees to keep your neck neutral.
- Lift only your shoulder blades, not your whole back.
- Exhale as you lift, inhale as you lower.
- Keep your elbows wide and relaxed.
Breathing: Exhale forcefully as you lift your shoulders to engage the deep core, and inhale deeply as you slowly return to the floor.
Common mistakes
- Pulling on the neck, which can cause unnecessary strain.
- Using momentum to swing up, which reduces the work your abs do.
- Lifting too high, which engages the hip flexors instead of the abs.
- Holding your breath, which creates internal pressure and increases fatigue.
Muscles worked
Primary: abs. Secondary: hip flexors.
Suggested sets & reps
Get fitter
3 sets × 12–15 reps, rest 60 s
Lose weight
3 sets × 15–20 reps, rest 45 s
Build muscle
3–4 sets × 10–12 reps, rest 60 s
Easier, harder & alternatives
Make it easier
Take care if…
- If you feel sharp pain in your neck or lower back, stop the movement immediately.
- If you have a history of spinal issues, check with a professional before adding core exercises to your routine.
General educational guidance, not medical advice. Stop on sharp pain and check with a qualified professional if unsure.
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Start free →Frequently asked questions
Should I feel this in my neck?
No. If you feel strain in your neck, you are likely pulling on your head. Keep your gaze fixed on your knees and focus on lifting with your chest.
How many times a week should I do crunches?
For beginners, 2–3 times per week is a great starting point to allow your muscles time to recover.
What if I feel this in my lower back?
Ensure your lower back stays pressed into the floor throughout the movement. If it arches, stop and try a smaller range of motion.