The short answer
Lying leg raise or Hanging leg raise?
The hanging leg raise is the better ab exercise once you can hang and hold still: the abs curl the pelvis against the whole weight of the legs, and in one lab study the straight-leg version drove the rectus abdominis past 130% of a maximal effort. Do the lying version if you have no bar, your grip gives out before your abs, or your back arches as the legs lower. In both, the curl of the pelvis at the top is the rep. Lifting the legs alone is hip flexor work, with the abs only holding the pelvis still.
Side by side
| Question | Lying leg raise | Hanging leg raise |
|---|---|---|
| What it is | Lie on your back, hands under the hips if needed, lift the legs toward the ceiling, then lower them without the lower back arching. | Hang from a bar with straight arms, lift the legs until the thighs pass parallel while the pelvis curls up, then lower them without swinging. |
| Equipment | A floor or a flat bench | A bar you can hang from at full stretch |
| What lifts the legs | The hip flexors, while the abs hold the pelvis so the back stays flat | The hip flexors, then the abs curl the pelvis toward the ribs at the top |
| Where the abs work hardest | Near the floor, where the legs are furthest out and the back wants to arch | At the top, as the pelvis tilts up |
| What gives out first | Control near the floor: the back starts to lift | Usually the grip, then the stillness |
| What the studies measured | Leg lifts lying down drew more on the rectus abdominis than the obliques | Straight-leg version: over 130% of a maximal effort for the rectus abdominis, about 3,000 N on the spine |
| To make it easier | Knees bent, hands under the hips, a shorter range | Hanging knee raises, or arm straps to take the grip out |
| To make it harder | Straight legs, a slower lowering, or a reverse crunch that lifts the hips | Straight legs, a 3 second lowering, then toes to bar |
| The usual cheat | Arching the back to lower the legs further | Swinging, so momentum from the bottom does the lifting |
Choose the lying leg raise when
- You have no bar, at home or in a hotel room.
- Your grip or your shoulders fail before your abs do when you hang.
- Your back arches as the legs come down. On the floor you can feel it and stop the range there.
- You want ab work after pull-ups, when your grip is already spent.
Choose the hanging leg raise when
- You can hold an active hang for 40 seconds and do 15 lying leg raises with a flat back.
- You want toes-to-bar for CrossFit, or the compression that an L-sit and a front lever ask for.
- You want a hard ab exercise without a cable machine or weights.
- You train pull-ups and want the extra time on the bar for your grip.
Using both in one week
Put the hanging raises where your grip is fresh: first in the core block, or on a day without heavy pulling. Use the lying version as the finisher after pull-ups, when the bar would test your hands more than your abs. If bigger abs are the goal, aim for at least 10 sets a week, the amount the 2026 American College of Sports Medicine position stand links to muscle growth, and split them between the two over two or three days.
From the floor to toes to bar
- Lying leg raise, knees bent, hands under the hips: 3 sets of 10 to 15, with the lower back flat for the whole set.
- Reverse crunch: the same start, then curl the hips off the floor at the top. This is the pelvic curl you will need on the bar.
- Hanging knee raise: knees to hip height, then curl the hips so the knees climb toward the chest, for 3 sets of 8 to 12. Let the swing settle between reps.
- Hanging leg raise: straight legs to past parallel, lowered over 2 to 3 seconds. 3 sets of 6 to 10.
- Toes to bar: press the bar down with straight arms, bring the knees toward the armpits, then flick the feet to the bar. Start with singles, then small sets with a small swing you control.
The numbers
- Hanging straight-leg raise, rectus abdominis
- Over 130% of a maximal effortMuscle activity recorded in 14 men; the external oblique reached 88% (McGill 2015).
- Spine compression in the same raise
- About 3,000 NThe weight of roughly 306 kg (3,000 / 9.81). A sliding forearm plank, the body saw, stayed under 2,500 N in the same study. Worth knowing with an irritable back.
- Psoas, a hip flexor, during sit-ups
- 15 to 35% of maximumFine-wire EMG in 8 adults; the curl-up stayed under 10% (Juker 1998).
- Most lower-ab activity of 5 exercises
- The reverse curlThe pelvis-lifting reverse curl beat the trunk curl and the v-sit for the lower rectus abdominis in 25 adults (Willett 2001).
Mistakes that cost the most
- Lifting the legs and calling it abs. If the pelvis never curls at the top, the hip flexors did the work.
- Swinging. Let the body settle still before every rep and take 2 to 3 seconds on the way down; a fast drop starts the next swing.
- A back that arches on the way down. Stop the legs where the lower back starts to lift and work from there, or bend the knees.
- Counting a set that ended because the hands opened. That was a grip set; use straps or move to the floor for the rest.
Questions people ask
Leg raises or knee raises: which is better for abs?
Knee raises, until you can curl the pelvis at the top with straight legs. Bending the knees shortens the lever, so the abs can finish the curl instead of the hip flexors just hauling a long, heavy leg. Straighten the legs when 3 sets of 10 knee raises are slow and still.
Hanging knee raises vs leg raises: when should I switch?
When every knee raise ends with the hips curling up and the body still, for 3 sets of 10 to 12. Try straight legs on the first set of a session, and go back to the knees on the sets where the curl disappears.
Sit-ups vs hanging leg raises: which is better?
Hanging raises, if you can hold the bar. In a 2006 study of 21 adults, a hanging knee-up in arm straps was among the strongest ab exercises tested, ahead of the crunch and the bent-knee sit-up, and the sit-up was among those with the highest hip flexor readings. Sit-ups still work the abs, but they share the job with the psoas far more than a curl-up does.
Sources
- Muscle activity and spine load during anterior chain whole body linkage exercises: the body saw, hanging leg raise and walkout from a push-upJournal of Sports Sciences, 2015
- Electromyographic analysis of traditional and nontraditional abdominal exercises: implications for rehabilitation and trainingPhysical Therapy, 2006
- Relative activity of abdominal muscles during commonly prescribed strengthening exercisesJournal of Strength and Conditioning Research, 2001
- Quantitative intramuscular myoelectric activity of lumbar portions of psoas and the abdominal wall during a wide variety of tasksMedicine and Science in Sports and Exercise, 1998
- Surface Electromyographic Activity of the Rectus Abdominis and External Oblique during Isometric and Dynamic ExercisesJournal of Functional Morphology and Kinesiology, 2022
- Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy AdultsMedicine and Science in Sports and Exercise (ACSM position stand), 2026
Figures on this page come from the studies above or from the arithmetic shown. Read how claims are reviewed and updated in How the guides are written.