Lying Leg Raise: How to Do It, Muscles Worked & Form

If you have ever wanted to work the lower part of your stomach and were not sure how, the lying leg raise is one of the simplest places to start. You lie on your back, lift your straight legs toward the ceiling, and lower them slowly. That is the whole movement. It needs no equipment and no gym, just a bit of floor space, so you can do it at home from day one. Most of the beginner core moves people already know, like crunches and planks, keep your legs still and move your upper body. The leg raise flips that around: your upper body stays put and your legs do the moving, which trains your abs in a new and useful way. You do not need a strong core to begin. If straight legs feel like too much today, you bend your knees and start there, and you get stronger by doing the version you can manage right now.

Muscles Worked

• Rectus abdominis (primary): This is the long sheet of muscle down the front of your stomach, the one people call the six-pack. In a leg raise it works hardest to keep your lower back flat and curl your pelvis while your legs move, and it is trained strongly through its lower portion.
• Hip flexors (iliopsoas, assist): These are deep muscles at the front of your hips that connect your thighs to your spine. They do the actual job of lifting your legs, so you will feel them working alongside your abs, especially near the bottom of each rep.
• Transverse abdominis (deep core): This is your deepest ab muscle, and it wraps around your middle like a built-in belt. It braces to keep your spine steady and stop your lower back from arching as your legs lower, which is exactly what keeps the movement safe.

How to Do the Lying Leg Raise

1. Lie flat on your back on a mat with your legs straight out in front of you and your arms resting by your sides, palms pressed into the floor. If you want extra support, slide your hands slightly under your bottom. Press your lower back gently down into the floor so there is no gap underneath it, and let your head, neck, and shoulders relax onto the mat.
2. Draw your belly button down toward your spine to switch on your abs, and keep your lower back pinned to the floor. Keep your legs straight, or with a small soft bend in the knees, and keep them pressed together. From here on the rule is simple: your lower back never lifts off the mat.
3. Slowly lift both legs toward the ceiling, keeping them straight and moving under control with no swinging or kicking. Breathe out as you raise them, and go up until your legs point roughly straight up, or as far as you can while your lower back stays flat. Let your abs do the lifting, not momentum.
4. Lower your legs back down slowly, breathing in as you go, and stop just before your feet touch the floor to keep the tension on your abs. If your lower back starts to arch up off the mat, that is your signal to stop lowering there. Reset your brace and raise again for your planned number of reps.

Coaching Cues

• Keep your lower back glued to the floor. This is the whole exercise. Press your back down so no gap opens up underneath it. If you cannot stop it lifting, do not lower your legs as far, or bend your knees more.
• Move slowly both ways. The slow lower is where most of the work happens. Take about two to three seconds to lower your legs and resist the urge to just let them drop.
• Lead with your belly, not your feet. Think about gently curling your hips toward your ribs rather than kicking your feet at the ceiling. That keeps the effort in your abs instead of only your hip flexors.
• Bend your knees to make it easier. If straight legs are too hard right now, bend your knees to about 90 degrees and raise from there. It trains the exact same thing at a level you can handle today.
• Breathe out on the way up. Exhaling as your legs rise helps your abs squeeze harder and stops you from holding your breath and tiring early.

Common Mistakes

• Letting the lower back arch. This is the most common mistake and the one that makes your back ache. If your back peels off the floor as your legs get near the bottom, you have gone past your limit. Shorten the range or bend your knees.
• Dropping the legs fast. Letting your legs crash back down uses momentum and skips the best part of the movement. Lower slowly and under control on every single rep.
• Swinging and kicking the legs up. Using a big swing to fling your legs up turns this into a momentum game rather than a core exercise. Slow down and let your abs, not a kick, do the lifting.
• Going too far too soon. Trying full straight-leg raises before you are ready just forces your back to arch. Start with bent knees, keep the range short, and earn the straighter version over a few weeks.

Sets, Reps & Programming

The lying leg raise is measured in reps. If you are brand new, start with 2 to 3 sets of 8 to 12 slow, strict reps, resting about a minute between sets, and use the bent-knee version if straight legs make your lower back arch. As it gets easier, straighten your legs a little more, add reps up to about 15, or slow the lowering phase down to make each rep harder without adding weight. Two or three short core sessions a week, tacked onto the end of a workout, is plenty. Once you can do straight-leg raises with your feet stopping just above the floor and your back staying flat, it is time to make the movement harder rather than just piling on reps: lower even slower, pause at the bottom, or eventually progress to hanging knee raises from a bar.

Safety

The lying leg raise is safe for almost everyone as long as you protect your lower back. The one rule that keeps it safe is to keep your lower back pressed into the floor: the moment it arches up, your back takes the load instead of your abs, and that is where the soreness comes from. If you feel it in your lower back, tuck your hands under your bottom for support, shorten the range so your feet stop higher, or bend your knees to reduce the strain. Never fling your legs or let them drop fast, since that jerks your lower back. If you are pregnant, returning from a back injury, or you feel any pinching in your lower back, keep the range small and strict, and check with a professional if anything feels off.

Track It in LiftLogic

It is easy to lose track of core work, because there is no loaded bar telling you last week was easier. Writing down how many strict reps you did, and whether you used the bent-knee or straight-leg version, turns a vague "do some leg raises" into a real exercise you can watch improve week after week. LiftLogic logs your reps and sets, remembers what you did last time, and keeps your core work in the same simple log as the rest of your training so nothing slips through the cracks. That little bit of tracking is often what keeps a nervous beginner coming back, because you can actually see yourself getting stronger. Download LiftLogic free on the App Store.