Sit Ups
Sit ups are a classic bodyweight core exercise targeting the abdominals. The full curl from flat to upright builds core strength and endurance, engaging both the upper and lower abs along with the hip flexors.
How to do it
- Lie flat on your back with your knees bent, feet flat on the floor, and hands behind your head.
- Engage your core and curl your torso upward toward your knees.
- Continue rising until your elbows nearly reach your thighs.
- Slowly lower your torso back to the starting position.
- Repeat for the desired number of repetitions.
Form cues
- Keep your feet flat on the floor.
- Engage your core before you lift.
- Curl your torso up smoothly.
- Lower your back down with control.
Breathing: Exhale as you curl upward, and inhale as you lower your torso back down to the floor.
Common mistakes
- Pulling on your neck with your hands strains your cervical spine and reduces core engagement.
- Using momentum to bounce up instead of muscle control means your abs do less work.
- Lifting your feet off the floor shifts the work away from your core and onto your hip flexors.
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 sets × 10–12 reps, rest 60 s
Easier, harder & alternatives
Take care if…
- If you feel lower back discomfort, ease off and try a smaller range of motion or a gentler crunch.
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
Why do my hip flexors hurt during sit ups?
Hip flexors often take over when feet lift or when the movement relies on momentum instead of slow abdominal control.
How often can I do sit ups as a beginner?
2 to 3 times per week is plenty to build endurance while giving your core adequate recovery time.
Should I hold my feet down under furniture?
It is better to keep feet unanchored to ensure your abdominals do the lifting work rather than your hip flexors.