How to Do Leg Raises with Proper Form

Leg raises are one of the most effective exercises for targeting your lower abs — the area that crunches and sit-ups barely touch. By lifting your legs against gravity while keeping your torso still, you load the lower portion of your rectus abdominis and hip flexors in a way few other exercises can match. And you don't need a single piece of equipment.

The problem is that leg raises have a reputation for causing lower back pain — and they will, if you do them wrong. The key is keeping your lower back glued to the floor throughout every rep. Once you learn that fundamental technique, leg raises become a safe and powerful core builder. Here's the complete guide.

Quick Facts

Step-by-Step Instructions

1. Lie flat on your back. Find a firm, flat surface — a mat on the floor is ideal. Lie with your legs fully extended and together, toes pointed or feet flexed (either works). Place your arms at your sides with palms flat on the ground.
2. Press your lower back into the floor. This is the most important setup cue. Actively press your lower back into the ground by engaging your deep core muscles. You should not be able to slide a hand under your lower back. Maintain this flat-back position throughout every rep.
3. Engage your core and lift your legs. Keeping your legs straight and together, slowly raise them toward the ceiling. Imagine you're pulling your belly button toward your spine as your legs lift. Control the movement with your abs — don't swing or use momentum.
4. Lift to vertical (or as high as your form allows). Ideally, raise your legs until they're perpendicular to the floor (90 degrees). If your lower back starts to arch before you reach that point, that's your current range of motion — work within it.
5. Pause briefly at the top. Hold for one second at the top of the movement, squeezing your abs. This pause eliminates momentum and maximizes muscle engagement.
6. Lower with control. Slowly lower your legs back toward the ground, taking 2-3 seconds on the descent. Stop just before your feet touch the floor to maintain continuous tension on your core. This is where most of the work happens — don't rush it.

Coach Ty's Form Tips

FitCraft's AI coach Ty coaches leg raises with a sharp focus on spinal safety and core engagement. Here are his most important cues:

• "Try to keep your legs straight as you lift them up." Straight legs create a longer lever arm, which increases the challenge on your core. If you can't keep them straight, a slight knee bend is acceptable — but aim for straight as your target form.
• "Keep your lower back pressed against the ground to protect your spine and isolate your core." This is non-negotiable. The moment your lower back arches, stress transfers from your abs to your lumbar spine. If your back lifts off the floor, shorten your range of motion or bend your knees.
• "Engage your core as you lift your legs, imagine pulling your belly button towards your spine." This cue activates your transverse abdominis — the deep core muscle that acts like a natural weight belt. It stabilizes your spine and amplifies abdominal engagement.
• "Breathe out forcefully as you lift your legs to engage your core even more." A forceful exhale during the lift compresses your abdominal cavity and increases core activation. Inhale on the way down, exhale forcefully on the way up.
• "Add a pause at the top of the movement before lowering for a challenge." A 2-3 second hold at the top eliminates all momentum and forces your abs to work isometrically. This is a simple way to increase difficulty without adding reps.
• "Keep your legs together as you lift them up." Legs drifting apart reduces tension on the core and changes the movement pattern. Keep your legs pressed together from start to finish.
• "Keep your hands at your sides for support." Your palms pressing into the floor provide stability and help you maintain the flat-back position. For a harder variation, place your hands behind your head — but only if your lower back stays flat.

Common Mistakes

• Lower back arching off the floor. This is the most common and most dangerous mistake. When your lower back lifts, your hip flexors take over and your lumbar spine bears the load. Press your lower back flat and reduce your range of motion if needed.
• Using momentum to swing legs up. Swinging your legs with momentum bypasses the muscles you're trying to train. If you need momentum to lift your legs, the exercise is too difficult at that range of motion — shorten it.
• Dropping legs too fast on the way down. The lowering phase is where the most muscle activation occurs. If you let gravity do the work, you're wasting half the exercise. Lower slowly and with control.
• Holding your breath. Breath-holding during core exercises increases intra-abdominal pressure and can spike blood pressure. Establish a breathing pattern: exhale as you lift, inhale as you lower.
• Bending knees excessively. While a slight knee bend is acceptable for beginners, significant knee bend shortens the lever arm so much that the exercise loses its primary benefit. Aim for the straightest legs your core strength allows.

Variations

• Bent-knee leg raises (easier). Perform the same movement with knees bent at 90 degrees. This shortens the lever arm and reduces core demand — ideal for beginners building foundational strength.
• Single-leg raises (easier). Raise one leg at a time while the other stays on the ground. This halves the load and is a good stepping stone toward the full two-leg version.
• Leg raises with hip lift. At the top of the movement, lift your hips off the floor by pressing your feet toward the ceiling. This adds a reverse crunch component and increases upper-ab engagement.
• Hanging leg raises (harder). Perform the movement while hanging from a pull-up bar. This is a significant progression that adds grip strength demand and allows a greater range of motion.
• Weighted leg raises. Hold a light dumbbell or medicine ball between your feet. The added weight increases resistance and makes each rep significantly more challenging.

How FitCraft Programs This Exercise

Leg raises are a core staple, but their placement, volume, and variation need to match your current ability. FitCraft's AI coach Ty uses your 32-step diagnostic assessment to get this right from day one.

If your assessment shows limited core strength, Ty starts you with bent-knee leg raises or single-leg raises — building the foundation before introducing the full movement. As your strength progresses, Ty transitions you to straight-leg raises and eventually adds pauses, tempo manipulation, or hip lifts to keep the challenge scaling.

Leg raises typically appear in dedicated core blocks at the end of your workout, often paired with complementary exercises like planks or bicycle crunches for a well-rounded ab circuit. Every placement decision is backed by exercise science and designed by an NSCA-certified exercise scientist.

FitCraft's gamification system — streaks, quests, and collectible cards — keeps you showing up for those core sessions that are easy to skip. Because visible abs aren't built in one great workout. They're built by showing up consistently, week after week. And that's exactly what FitCraft makes happen.