Core · Spinal flexion
Leg Raises
The lying leg raise is a floor exercise where you raise both straight legs from the floor towards vertical and lower them under control. It trains the abdominals and hip flexors, and the abdominal work comes mainly from curling the pelvis backwards at the top of each rep.
Also known as: Lying leg raise, Floor leg raise, Supine leg raise
- Muscle group
- Core
- Movement pattern
- Spinal flexion
- Type
- Isolation
- Equipment
- Bodyweight
- Difficulty
- Beginner
What muscles does the leg raises work?
Primary movers
- Rectus abdominis
- Hip flexors
Assisting muscles
- Obliques
- Transverse abdominis
There is an important distinction in this exercise. Raising the legs from the floor to vertical is mostly hip flexion, produced by the iliopsoas and rectus femoris. Through that phase the abs work isometrically, holding the pelvis and ribcage together rather than producing the movement.
The abdominal work proper happens at the top. Once you curl the pelvis backwards, tilting the hips towards your ribs, the rectus abdominis genuinely shortens under load. That small extra movement is the part of the rep that trains the abs most directly, and it is the part most people skip.
The lowering phase is where the anti-extension demand appears. As the legs descend, their weight pulls the pelvis into a forward tilt and would arch the lower back. The abs contract to prevent it, which is why slow lowering is more productive than a fast one.
The transverse abdominis and obliques work throughout to keep the trunk connected while a long lever swings below it. If the lower back lifts off the floor, they have been overwhelmed, and the lumbar spine takes the load instead.
The hip flexors being heavily involved is not a flaw, but it does mean the exercise is only partly an ab movement. That is worth knowing if you are choosing between this and something like a hanging leg raise with a deliberate pelvic curl, where the abs take a larger share.
How to do the leg raises
Setup
- 1
Lie flat on your back with your legs straight and together.
- 2
Place your hands palms down beside your hips, or tuck them under your glutes for lower-back support.
- 3
Press your lower back into the floor and keep it there.
- 4
Draw your ribs down so your torso is braced before the first rep.
- 5
Lift your heels a few inches off the floor to take up tension.
Execution
- 1
Raise both legs together, keeping them straight, until they are roughly vertical.
- 2
At the top, curl your pelvis slightly off the floor towards your ribs. This is the ab portion of the rep.
- 3
Pause briefly in that curled position.
- 4
Lower over three to four seconds, keeping the legs straight.
- 5
Stop before your heels touch the floor, at the lowest point where your lower back stays flat.
- 6
Begin the next rep from there without resting the legs down.
Common leg raises mistakes
Letting the lower back arch on the way down
Lowering the legs past the point the abs can control, so a gap opens under the lumbar spine. This is the most common fault in the exercise and the one that causes back discomfort.
The fix: Stop the descent while the back is still flat, even if that means your legs finish well above the floor. Tucking your hands under your glutes helps while you build strength.
Skipping the pelvic curl at the top
Stopping when the legs reach vertical. That completes the hip flexion but never asks the abs to shorten, so most of the rep is hip flexor training.
The fix: At the top, lift your hips a couple of inches off the floor by curling the pelvis towards your ribs. The range is small and the difference in ab involvement is large.
Swinging the legs for momentum
Dropping the legs quickly and bouncing into the next rep, so the rebound does the work rather than the muscles.
The fix: Take three to four seconds to lower and start each rep from a controlled stop. Fewer reps done this way are worth considerably more.
Straining the neck
Craning the head forward to watch the legs, which tightens the neck and contributes nothing to the movement.
The fix: Rest your head on the floor and look at the ceiling. If you want a slight crunch position, lift the shoulder blades rather than pushing the chin forward.
How many sets and reps?
| Goal | Sets | Reps | Load | Rest |
|---|---|---|---|---|
| Hypertrophy | 3 | 10–15 | Bodyweight, slow eccentric | 60 s |
| Beginner progression | 3 | 8–12 | Bent knees, partial range | 45–60 s |
| Loaded progression | 3 | 8–12 | Light dumbbell between the feet | 60–90 s |
Leg raises are a reasonable entry point to lower ab training, mostly because they need no equipment and the difficulty can be scaled simply by bending the knees. Three sets of 10–15 with a genuine pelvic curl at the top and a slow descent covers it. The natural progression is towards the hanging version, which adds a longer range and removes the floor's assistance. Do not chase high rep counts here: if you are doing sets of thirty, the reps are too fast or the range is too short, and slowing down will fix both.
Running the leg raises in your next block? Hercules logs every set, shows last session's numbers before you lift, and suggests when to add weight.
Get it on Google PlayLeg Raises variations and alternatives
Bent-Knee Leg Raise
EasierBending the knees shortens the lever substantially, which is the simplest way to scale the exercise if your lower back lifts.
Hanging Leg Raise
HarderHanging from a bar removes the floor's support and lengthens the range, making it the clear progression once floor raises are easy.
Flutter Kicks
EasierSmall alternating movements near the bottom of the range, which trains the same anti-extension hold for time rather than reps.
Weighted Leg Raise
HarderHolding a light dumbbell between the feet adds load once bodyweight reps are comfortable.
Dead Bugs
EasierOne limb at a time rather than both legs, which halves the load on the abs and makes keeping the back flat far more achievable.
Frequently asked questions
Do leg raises work the lower abs?
They work the rectus abdominis, which is a single muscle rather than separate upper and lower sections, though the lower portion can be emphasised. That emphasis comes from the pelvic curl at the top, not from raising the legs. A leg raise without that curl is largely a hip flexor exercise.
Why do leg raises hurt my lower back?
Because the legs are descending further than your abs can control, letting the lumbar spine arch under a long lever. Shorten the range, keep your lower back pressed into the floor, and tuck your hands under your glutes. Bending your knees also reduces the load immediately.
Are hanging leg raises better than lying leg raises?
For most purposes yes. Hanging gives a longer range, removes the floor's support and allows the pelvic curl to be performed more fully. Lying leg raises remain useful as a progression towards them and for anyone whose grip or shoulders cannot yet support a hang.
Should I keep my legs straight?
Straight legs are harder because the lever is longer, so use them once you can keep your lower back flat throughout. Until then, bent knees are the correct choice. A clean rep with bent knees trains the abs better than an arched rep with straight ones.
How many leg raises should I do?
Three sets of 10–15 controlled reps, two or three times a week. Prioritise the three to four second lowering phase and the pelvic curl at the top over adding reps. When bodyweight sets stop being challenging, hold a light dumbbell between your feet or move to the hanging version.
Hercules tracks every leg raises you log, shows you last session's numbers before you lift, and flags when your progress stalls.
Get it on Google Play