Leg Raise
The leg raise is a floor-based ab exercise where you lie on your back and lift both straight legs from the floor to roughly hip height, using nothing but your own bodyweight and a long lever. Keeping the knees straight instead of bent, like in the easier leg pull-in, increases the demand on the lower abdominals considerably, which is why it's rated a step up in difficulty even though it needs no equipment.
Why it works
A straight leg is a much longer lever than a bent one, so lifting it takes noticeably more force from the muscles that tilt the pelvis and flex the hip. The abdominals have to work overtime to keep the lower back pressed into the floor while the hip flexors do the actual lifting, and it's that stabilizing job, resisting the pull of gravity on two extended legs, that turns the leg raise into a genuine core-strengthening exercise rather than just a hip flexor drill.
Set up
- Lie flat on your back with your legs extended and your hands flat on the floor at your sides, or tucked under your hips for extra support.
- Press your lower back into the floor before your legs leave the ground.
- Keep your knees straight but not locked throughout the set.
How to do it
- Lift both legs together off the floor, keeping the knees straight, until they reach roughly a right angle to your torso.
- Stop the lift immediately if your lower back starts to arch off the floor.
- Pause briefly at the top of the movement.
- Lower your legs back down slowly, stopping just before your heels touch the floor to keep tension on your abs.
- Repeat for the set without letting the legs drop on the way down.
Form cues
- Lower back glued to the floor
- Knees straight, not locked
- Lower slowly, don't let gravity do it
- Stop the range where your back stays flat
Breathing: Exhale as you lift your legs, inhale as you lower them back down.
Common mistakes
Letting the lower back arch as the legs lower.
Fix: Shorten the range of motion, stopping the descent well above the floor until your core strength catches up.
Bending the knees to make the lift easier.
Fix: If straight legs are too hard right now, use the leg pull-in with bent knees instead and build up to this version.
Dropping the legs quickly at the bottom.
Fix: Slow the lowering phase down; the negative portion is where most of the ab work happens.
How to program it
- This is more demanding than a bent-knee variation, so two to three sets of 10 to 15 reps is plenty for most people.
- Since it's an intermediate bodyweight move, spacing it across two or three sessions in a week gives the lower abs enough recovery between sets.
- It's a good finisher after heavier compound lifts, when you have less energy left to cheat the range of motion with momentum.
Safety notes
- Keep the range of motion within what your lower back can control; a flat back matters more than how high the legs go.
- If lower back discomfort shows up, drop back to the bent-knee leg pull-in until your core catches up to this version.
Exercise profile
- Force
- Pull
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
How high should I lift my legs during a leg raise?
Around 90 degrees to your torso is plenty. Going higher doesn't add much ab work once your hips start to tuck under, and going lower than your back can control just invites arching.
Leg raise vs leg pull-in: which should I do?
Start with the leg pull-in if straight-leg raises make your lower back arch. Once you can keep your back flat through a full leg pull-in set, the straight-leg raise is the natural next step.
Why does this hurt my lower back?
Almost always because the lower back is lifting off the floor to compensate for a weak or fatigued core. Shorten the range and keep your back pressed down for the whole set.
How do I make the leg raise harder?
Slow the tempo down, especially on the way down, before adding equipment like ankle weights or moving to a hanging leg raise, which removes the floor entirely.
How many days a week should I train leg raises?
Two to three sessions a week is plenty for most people; the lower abs recover fairly quickly from bodyweight work, but form quality matters more here than piling on extra days.