Flat Bench Lying Leg Raise
The flat bench lying leg raise has you lying flat on a bench, legs straight, lifting them up toward the ceiling and lowering them back down under control. It isolates the lower abdominals through hip flexion with a straight leg, which creates a longer lever and a tougher hold than a bent-knee version. It works well for anyone with a base of core strength who wants to target the lower abs more directly than a standard crunch does.
Why it works
With your legs straight, the distance from your hip joint to your feet is at its longest, which means your hip flexors and lower abdominals have to work against a much bigger lever arm than they would with bent knees. As your legs lower toward the bench, gravity pulls harder on that long lever, and your abs have to resist your lower back arching off the bench to compensate. That's the real test of this exercise: keeping your lower back flat against the bench even as your legs get closer to horizontal.
Set up
- Lie flat on a bench with your legs extended straight and your hands gripping the bench above your head for stability.
- Press your lower back flat against the bench before lifting your legs.
- Keep a very slight bend in the knees rather than locking them out completely.
- Start with your legs together and pointed toward the ceiling.
How to do it
- Lower your legs slowly toward the bench, keeping them straight.
- Stop the descent at the point where your lower back would start to lift off the bench.
- Pause briefly at your lowest controlled position.
- Raise your legs back up toward the ceiling using your lower abs.
- Keep your lower back pressed flat against the bench for the entire rep.
- Repeat without swinging your legs or using momentum to help the raise.
Form cues
- Lower back stays flat against the bench the whole time.
- Lower your legs only as far as you can control.
- Keep the legs straight, not bending at the knees to cheat the range.
- Raise with the lower abs, not by yanking with the hip flexors.
Breathing: Exhale as you raise your legs, inhale as you lower them back down.
Common mistakes
Letting the lower back arch off the bench as the legs lower.
Fix: Stop the descent at the point right before your lower back lifts; that range, not a lower one, is what your current strength can actually control.
Bending the knees to make the exercise easier without meaning to.
Fix: Keep a fixed, very slight bend throughout; if the knees bend more as you fatigue, shorten the range instead of letting the legs collapse.
Using momentum to swing the legs up quickly.
Fix: Slow the tempo on both the raise and the lower; a controlled rep at a shorter range beats a fast one at a longer range.
Gripping the bench so hard that the shoulders and neck tense up.
Fix: Hold the bench firmly enough for stability, but keep your shoulders relaxed and away from your ears.
How to program it
- 2 to 3 sets of 8 to 12 reps is a solid target, since the long lever makes this a demanding move even at a low rep count.
- Two or three times a week is enough for most people; the abs recover quickly, but full-range leg raises are taxing on the hip flexors too.
- If you can't keep your lower back flat for a full rep, build up range gradually rather than forcing the legs all the way down.
- Pairs well with a compound core move like the plank on alternating days while your lower-ab strength catches up to your ambition.
Safety notes
- Never let the lower back arch away from the bench to gain range; that shifts the load onto the spine instead of the abs.
- If you feel strain in the lower back rather than effort in the lower abs, shorten the range or switch to the bent-knee regression.
Exercise profile
- Force
- Pull
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
How low should I lower my legs during leg raises?
Only as low as you can go while keeping your lower back flat against the bench. The moment your back starts to lift, that's your true range for now, regardless of how far your legs could otherwise drop.
Why do leg raises hurt my lower back?
Usually because the legs are lowering past the point the lower abs can control, letting the back arch and take on the load instead. Shorten the range and keep the back pressed flat.
Are leg raises better than crunches for abs?
They target the lower fibers of the rectus abdominis more directly than a crunch does, since the resistance comes from the weight of the legs rather than the torso. Both have a place in a well-rounded core routine.
What's an easier version of the lying leg raise?
Bending the knees and pulling them toward your chest, as in a leg pull-in, shortens the lever and makes the exercise noticeably easier while still training the same lower abs.