Stop Doing Floor Leg Lifts Like This (Save Your Back)

You might think lying on the ground and lifting your legs is the safest way to train your core. It looks simple enough, right? But here is the hard truth: floor leg lifts are one of the most frequently butchered exercises in the gym. When performed incorrectly, they stop being an ab builder and start being a lower-back destroyer.

If you feel a sharp pinch in your lumbar spine or your hips snap with every rep, your form needs an immediate overhaul. We aren't just trying to move limbs from point A to point B here; we are trying to create tension in the deep abdominal wall. Let’s fix your technique so you can actually benefit from this powerhouse movement.

Key Takeaways: Perfecting the Leg Raise

• Posterior Pelvic Tilt is Non-Negotiable: You must flatten your lower back against the floor before your legs even move.
• Control the Eccentric: Gravity is not your friend. Lower your legs slowly to maximize time under tension.
• Range of Motion Matters: Only lower your legs as far as you can keep your back glued to the ground.
• Hip Flexor Awareness: If your hips burn more than your abs, you are likely compensating. Reset and engage the core first.

Why the Lying Floor Leg Raise is Essential

The lying floor leg raise targets the lower portion of the rectus abdominis—an area that crunches often miss. While it is impossible to completely isolate the "lower abs" (the muscle is one long sheet), this movement changes the leverage to place significantly more stress on the bottom half.

However, it is a double-edged sword. Because your legs are heavy levers, your hip flexors (specifically the psoas) want to take over. If your core isn't strong enough to stabilize the pelvis, the psoas pulls the spine into an arch. That is where the injury risk lies. Mastering the leg raise on the floor is about learning to turn off the hip flexors and force the abs to do the heavy lifting.

Step-by-Step: How to Execute Leg Raises on Floor

1. The Setup

Lie flat on your back. Place your hands underneath your glutes or out to the sides for stability. Placing hands under the hips is a great modification if you struggle with back pain, as it naturally tilts the pelvis into a safer position.

2. The Lock-In

Before you lift, exhale sharply to drive your ribcage down. Press your lower back into the floor. Imagine there is a bug under your spine and you are trying to crush it. This is your anchor point.

3. The Movement

Keep your legs straight (or slightly bent if you have tight hamstrings) and lift them toward the ceiling. Stop when your hips are at 90 degrees. Pause at the top.

4. The Descent

Slowly lower your legs. This is the most important part of the leg raise on floor. Stop the descent the moment you feel your lower back start to peel off the ground. That is your active range of motion. Do not go lower until you get stronger.

The Science: Why Your Back Hurts

The primary reason people fail at the floor leg raise is a lack of anterior core stiffness. When you lower your legs, the weight creates a massive extension moment on the spine.

If the abdominals fatigue or are weak, the body defaults to an "anterior pelvic tilt." This compresses the facet joints in the lumbar spine. If you finish a set and your back feels tight, you weren't training your abs; you were training your spine to tolerate shear force. That is a losing game.

My Training Log: Real Talk

I remember clearly when I realized I was doing these wrong. I was training in a garage gym with no mats, just straight concrete. I was knocking out sets of 20, feeling confident.

But it wasn't my abs that stopped me; it was the bruising on my tailbone and the distinct grinding sensation in my hips. I realized that on the descent, my pelvis was rocking forward, grinding my sacrum into the cement. I wasn't controlling my core; I was just swinging my legs.

I had to drop my ego and put my hands under my butt to manually force a posterior tilt. I cut my reps from 20 down to 8. The burn shifted from my hip creases to my deep stomach immediately. If you feel your hip bone popping or your tailbone grinding, stop. You aren't stabilizing correctly.

Conclusion

The floor leg raise is a staple for a reason, but it demands respect. It is not a mindless accessory movement to throw in at the end of a workout when you are exhausted. Treat it with the same technical focus you would a heavy squat. Keep your back flat, control the speed, and stop letting your ego dictate how low your legs go.

Frequently Asked Questions

Do floor leg lifts burn belly fat?

No exercise can spot-reduce fat. While leg lifts strengthen the abdominal muscles underneath the fat, revealing those muscles requires a caloric deficit and overall fat loss through nutrition and training.

Why do my hips click during leg raises?

This is often "snapping hip syndrome," caused by a tight tendon moving over a bony prominence in the pelvis. Try reducing your range of motion or slightly bending your knees to alleviate the tension.

Can I bend my knees during the exercise?

Absolutely. A bent-knee variation (often called a knee tuck) reduces the lever arm, making the move easier on the lower back while still targeting the core. It is an excellent regression for beginners.