Lying Bent Legs Raise
- Target muscle
- —
- Equipment
- Body weight
- Body part
- Waist
- Type
- Strength
The Lying Bent Legs Raise is a bodyweight core exercise performed supine on the floor, targeting the rectus abdominis with meaningful involvement from the hip flexors (iliopsoas). Keeping the knees bent at roughly 90 degrees reduces the leverage arm compared to straight-leg raises, shifting more demand onto the lower abdominal region. It is a reliable choice for building anterior core strength and improving control of the lumbopelvic complex.
How to do the Lying Bent Legs Raise
- 1Lie flat on your back on a firm surface with your arms at your sides, palms facing down.
- 2Bend both knees to approximately 90 degrees and lift your feet off the floor so your thighs are vertical and your shins are roughly parallel to the floor — this is your starting position.
- 3Press your lower back gently into the floor by engaging your core before any movement begins.
- 4Exhale and draw your knees toward your chest in a controlled arc, keeping the 90-degree bend at the knees throughout.
- 5Stop when your hips begin to lift off the floor or you feel your lower back losing contact — do not roll onto your tailbone.
- 6Hold the top position for one count, feeling the abdominals fully contracted.
- 7Inhale and slowly lower your legs back to the starting position, resisting the pull of gravity the entire way down.
- 8Stop with your feet hovering just above the floor rather than resting them, to keep tension on the core.
- 9Repeat for the desired number of reps, maintaining steady breathing and a stable lower back throughout.
Form tips
- Press your palms or fingertips lightly into the floor to cue lat engagement, which helps anchor the ribcage and prevents your torso from rocking.
- Think of curling your pelvis toward your ribcage rather than simply swinging your knees — this subtle pelvic tilt maximises lower ab recruitment.
- Lower your legs at half the speed you raise them; the eccentric phase is where most of the abdominal work happens.
- Keep your neck long and your head relaxed on the floor — any chin-tuck tension indicates you are compensating for a weak core.
- If your lower back arches or lifts off the floor on the descent, shorten your range of motion until your core is strong enough to control the full arc.
Common mistakes
- Letting the lower back arch off the floor at the bottom — this transfers load to the lumbar spine instead of the abs and increases injury risk; stop the descent the moment you feel the back lift.
- Using momentum by swinging the legs rather than lifting with a controlled muscular contraction — this bypasses the abs and turns the movement into a hip flexor swing.
- Holding the breath throughout the set — breath-holding raises intra-abdominal pressure and causes compensatory bracing patterns; exhale on the way up, inhale on the way down.
- Collapsing the knee angle so the legs extend on the way up — straightening the legs increases lever length and shifts work away from the abs toward the hip flexors.
- Resting the feet on the floor between every rep — this eliminates the time-under-tension that makes the exercise effective; keep the feet hovering to maintain continuous core engagement.
Frequently asked questions
What is the difference between a lying bent legs raise and a lying straight leg raise?
Bending the knees shortens the lever arm created by your legs, which reduces the load on the hip flexors and makes it easier to keep the lower back flat. This lets the rectus abdominis — particularly the lower portion — do more of the work. Straight-leg raises increase total resistance and hip flexor demand, making them a progression once you have mastered the bent-knee version.
How many reps and sets should I do?
For most people, 3 sets of 12 to 20 controlled reps works well as part of a core circuit. Prioritise quality over quantity — if your lower back lifts off the floor or you lose the 90-degree knee angle, stop the set. Once 20 reps feel easy with perfect form, slow the eccentric phase or add a pause at the bottom before progressing to harder variations.
Why do I feel this more in my hip flexors than my abs?
Hip flexor dominance is common when the core is not pre-activated before the movement starts or when the range of motion is too large. Begin each rep by pressing your lower back into the floor and bracing your abs before you move your legs. Also check that you are not letting your lumbar spine arch on the descent — shortening the range of motion until your abs can control it will redirect the work where it belongs.
Is this exercise safe for people with lower back pain?
It can be appropriate for some individuals with lower back issues, but only when the lower back stays in contact with the floor throughout the movement. If you cannot maintain a neutral spine, the exercise places compressive load on the lumbar discs and should be avoided until your core is strong enough to support it. Consult a qualified health professional before adding this movement if you have an existing back condition.
Where should I place my hands during the exercise?
Palms flat on the floor beside your hips is the standard position — it provides a stable base and mild lat engagement to keep the ribcage anchored. Avoid tucking your hands under your lower back, as this creates a false sense of support and prevents you from learning to stabilise with your own musculature.
