Lying Leg Raises (Bent Knee)
Lying leg raises with bent knees are a bodyweight exercise targeting the abdominal muscles. The bent knee position reduces the lever arm and decreases demand on the hip flexors compared to straight-leg raises, making it more accessible.
How to do it
- Lie flat on your back with your hands under your glutes for support and knees slightly bent.
- Keeping your lower back pressed into the floor, raise your legs toward the ceiling.
- Stop when your legs are perpendicular to the floor or when you feel your lower back lift.
- Slowly lower your legs back toward the floor without touching it.
- Repeat for the desired number of repetitions.
Form cues
- Press your lower back firmly into the floor.
- Keep a gentle, fixed bend in your knees throughout.
- Raise your legs smoothly using your abdominal muscles.
- Lower your feet back down slowly without touching the floor.
Breathing: Exhale as you lift your legs toward the ceiling, and inhale slowly as you lower them back down.
Common mistakes
- Arching the lower back away from the floor, which can strain your spine and reduces ab engagement.
- Using momentum to swing the legs up, meaning your abs do less of the actual work.
- Dropping the legs too fast at the bottom, losing control and reducing muscle time under tension.
Muscles worked
Primary: abs. Secondary: hip flexors, obliques.
Suggested sets & reps
Get fitter
3 sets x 10-12 reps, rest 60 s
Lose weight
3 sets x 12-15 reps, rest 45 s
Build muscle
3-4 sets x 10-12 reps, rest 60 s
Easier, harder & alternatives
Make it harder
Take care if…
- If you feel sharp lower back pain, ease off and choose a gentler core option.
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 should I bend my knees for this leg raise?
Bending your knees shortens the lever arm, which makes the exercise more accessible and puts less strain on your lower back and hip flexors compared to straight-leg raises.
What should I do if I feel this in my lower back instead of my abs?
Stop and reset. Press your lower back firmly into the floor before you start, and try raising your legs only halfway up until your core strength improves.
How many times a week can I practice lying leg raises?
2 to 3 times per week is plenty for most beginners to allow for adequate recovery and muscle adaptation.