How to Do Leg Raises on the Floor
A leg raise is a core exercise done lying on your back: lift your straight legs until they point at the ceiling, then lower them slowly. Your hip flexors lift your legs, and your abs stop your pelvis tipping and your lower back arching. Most people do 3 sets of 10 to 20 reps.
How to do a leg raise
- Lie on your back on a mat with your legs straight and together and your arms by your sides, palms down.
- Brace your abs and let your lower back settle toward the floor. You do not need to crush it flat.
- Breathe out and lift both legs together, knees straight or slightly soft, until they point at the ceiling.
- Lower them over 2 to 3 seconds. Stop as soon as your lower back starts to lift off the floor, even if your feet are still high.
- Start the next rep from that point, without resting your heels on the floor or bouncing them.
The bottom of the rep is the hard part
Your legs make up about a third of your body weight, and your hip flexors hold all of it on a lever. The further your feet sit from your hips, measured along the floor, the harder they pull. With your legs vertical that distance is close to zero, so the top of the rep is a rest. Just above the floor it is at its longest. That is where the rep is hardest, and where your lower back is most likely to arch. Bending your knees brings your shins closer to your hips, so every point on the curve drops.
Lower only as far as your lower back stays down. In 100 healthy 18 to 29 year olds, men kept it flat down to an average of 15 degrees above the floor and women to 37 degrees (Krause 2005). Start higher and work down.
Your lower back: flat, neutral or hands under your hips?
As your legs lower, their weight pulls your pelvis into a forward tip, and that tip is what arches your lower back. It starts early. In one study the pelvis began to tip within the first few degrees of lowering from vertical, even in people trying to stop it (Zannotti 2002). Your abs' job in a leg raise is to resist that pull.
You do not need to press your back into the floor as hard as you can. In a lying double straight-leg hold with the feet 5 cm off the floor, a neutral pelvis and a pelvis tucked under drew the same upper and lower rectus abdominis activity, and both drew more than an arched back (Workman 2008). Keep the arch out; you do not have to force it flat.
Sliding your hands under your hips tips your pelvis back a little and makes the arch easier to control. It is a common fix, but no study we found has tested it. If you need it, keep the rest of the rep the same and work toward hands by your sides.
Muscles worked
From bent knees to a full leg raise
Move up a step when you can do 3 sets of 20 strict reps, and drop back to 10. Lowering your legs further is the cheapest way to make the rep harder, because the bottom is where the load peaks.
Leg raise claims the research does not back
Four claims most leg raise guides repeat:
- Leg raises train the lower abs, crunches the upper. The rectus abdominis is one muscle. EMG found no difference between its upper and lower parts in curl-ups or leg raises (Lehman 2001). One ultrasound study saw the lowest segment change most in a leg raise, but the crunch changed the muscle 36% more overall (Gomirato 2023).
- Press your lower back into the floor as hard as you can. A neutral pelvis drew the same rectus activity as one tucked under, and both beat an arch (Workman 2008). And the pelvis tips a little as soon as your legs leave vertical, even when you try to stop it (Zannotti 2002). Control the arch; do not chase a perfectly flat back.
- Your psoas yanks your lower back into an arch. The psoas has very little leverage to bend the lower spine, though it squeezes it hard at full effort (Bogduk 1992). The arch comes from your pelvis tipping forward as your legs lower, which is what your abs resist.
- Leg raises burn belly fat. Six weeks of ab exercise, 5 days a week, did not reduce belly fat or waist size (Vispute 2011). Visible abs come from lower body fat.
Lying leg raise vs hanging leg raise vs crunch
| Attribute | Lying leg raise | Hanging leg raise | Crunch |
|---|---|---|---|
| Moves at | Your hips | Your hips first, your spine at the top | Your spine |
| Hardest point | Legs just above the floor | Legs at hip height | Shoulder blades off the floor |
| Limited by | Lower back control | Grip, swinging | Your abs |
| Make it harder | Lower your legs further, then ankle weights | Straighter legs, then toes to bar | Arms overhead, then a plate |
| Easy to cheat by | Arching your lower back | Swinging | Pulling on your head |
Start with the lying leg raise; it needs only the floor. The hanging leg raise is the harder version once your grip can hold you. Both are mostly hip flexion, so pair them with a crunch, which curls your spine: the crunch changed the rectus abdominis 36% more than a leg raise to vertical (Gomirato 2023).
Sets, reps and progression
Do leg raises at the end of a session, 2 to 3 times a week. Stop each set 0 to 2 reps short of failure, or as soon as your lower back starts to arch, whichever comes first. Sets taken close to failure build muscle across a wide range of reps (Schoenfeld 2021), so pick a range you can keep strict.
Progress by lever before you add reps. When every set reaches 20 strict reps, lower your legs further or move up a step in the progression above, and drop back to 10.
Common mistakes
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Arching your lower backYour pelvis tips and your back takes the strain. Stop the lowering higher, bend your knees, or slide your hands under your hips.
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Dropping your legsThe lowering half is the hard half. Take 2 to 3 seconds on the way down.
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Bouncing your heels off the floorThe bounce starts the next rep for you. Stop just above the floor, or higher, and lift from a still position.
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Swinging past verticalPast vertical your legs fall toward you and the load disappears. Stop when they point at the ceiling.
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Pushing with your armsPressing your palms hard into the floor lifts your legs with your shoulders. Keep your hands relaxed.
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Holding your breathBreathe out as your legs rise and in as they lower.
Leg raise variations
Questions people ask
Do leg raises work lower abs?
They work your whole rectus abdominis, which is one muscle. EMG found no upper vs lower difference in leg raises (Lehman 2001). One ultrasound study saw the lowest segment change most in a leg raise (Gomirato 2023), but no training study has tested whether that grows the lower abs more.
Are leg raises bad for your back?
Not for most people, as long as your lower back does not arch. As your legs lower, their weight tips your pelvis forward (Zannotti 2002). Stop each rep where your back starts to lift, bend your knees, or do one leg at a time. If any leg raise still hurts, swap in a dead bug.
Why do leg raises hurt my hip flexors?
Because your hip flexors do the lifting. Two-leg lifts drew more iliacus activity than hip-flexion sit-ups (Andersson 1997). A burn there is normal. Pain at the front of the hip is not; bend your knees and shorten the range until it goes.
Are leg raises better than crunches?
Neither is better; they work your abs in different ways. In a leg raise your abs hold your pelvis still, and in a crunch they curl your spine. A lowering leg raise with the pelvis tucked drew more ab activity than a held curl-up (Shields 1997), but the crunch changed the rectus abdominis 36% more in an ultrasound study (Gomirato 2023). Do both.
How many leg raises should I do a day?
You do not need them every day. Do 3 sets of 10 to 20, 2 to 3 times a week, ending each set when your lower back starts to arch or 0 to 2 reps short of failure. Once 20 come easy, lower your legs further instead of doing more.
How many leg raises should I be able to do?
On Gravitus, as of September 2026, the median best set logged as lying leg raises is 15 reps for both men and women, and the top 10% have done 28 or more (men) or 25 or more (women) (1,400+ men, 800+ women). Count only reps where your lower back stayed down.
Do leg raises burn belly fat?
No. Six weeks of ab exercise, 5 days a week, did not reduce belly fat or waist size (Vispute 2011). Leg raises strengthen the muscles under the fat, and lower body fat is what makes them visible.
Log every set and Gravitus charts your reps, times and records from week to week.
Get GravitusRelated exercises
- Krause et al. 2005. Arch Phys Med Rehabil 86(7):1345-1348.
- Zannotti et al. 2002. J Orthop Sports Phys Ther 32(9):432-436.
- Workman et al. 2008. J Strength Cond Res 22(5):1563-1569.
- Andersson et al. 1997. Eur J Appl Physiol 75(2):115-123.
- Park and Park 2019. J Back Musculoskelet Rehabil 32(5):797-802.
- Shields and Heiss 1997. Spine 22(16):1873-1879.
- Bogduk, Pearcy and Hadfield 1992. Clin Biomech 7(2):109-119.
- Lehman and McGill 2001. Phys Ther 81(5):1096-1101.
- Gomirato and Grenier 2023. Int J Exerc Sci 16(1):1077-1086.
- Vispute et al. 2011. J Strength Cond Res 25(9):2559-2564.
- Schoenfeld et al. 2021. Sports 9(2):32.