Crunches
Crunches are a foundational bodyweight exercise targeting the rectus abdominis. By curling the upper body off the ground, they isolate the abdominal muscles and build core strength and endurance.
How to do it
- Lie flat on your back with your knees bent and feet flat on the ground.
- Place your hands behind your head with your elbows pointing outward.
- Engaging your abs, curl your upper body off the ground toward your knees.
- 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 firmly into the floor throughout the movement.
- Lift your shoulder blades just a few inches off the ground.
- Look up and slightly forward to keep your neck relaxed.
- Exhale as you curl upward, engaging your abs.
Breathing: Exhale as you curl up toward your knees, and inhale slowly as you lower back down to the floor.
Common mistakes
- Pulling on your neck with your hands, which can cause neck strain and reduces ab engagement.
- Using momentum by swinging your torso up, which decreases core activation.
- Lifting the lower back off the floor, which shifts the work away from your abs.
Muscles worked
Primary: abs. Secondary: hip flexors, obliques.
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 × 10–15 reps, rest 60 s
Easier, harder & alternatives
Make it easier
Make it harder
Alternatives
Take care if…
- If you have neck or lower back discomfort, ease off or choose a gentler core option.
General educational guidance, not medical advice. Stop on sharp pain and check with a qualified professional if unsure.
Get this in your plan
Create a free account for an AI-built plan that puts moves like this into your week.
Start free →Frequently asked questions
Should I feel crunches in my lower back?
No, if you feel strain in your lower back, your hips might be taking over or your lower back is arching. Focus on keeping your lower back pressed into the floor.
How often can I do crunches as a beginner?
2 to 3 times per week is a great starting point to allow your abdominal muscles adequate rest and recovery.
Why does my neck hurt during crunches?
Neck pain usually happens when you pull your head forward with your hands. Instead, support your head gently and lead the movement with your chest and abs.