Lying Leg Raises Muscles Worked: The Definitive Anatomy Guide
You hit the floor, slide your hands under your glutes, and start rep one. You are chasing that elusive lower abdominal burn. But by rep ten, your lower back feels tight and your hip flexors are screaming louder than your core. This is the most common scenario I see in the gym when athletes don't fully understand the lying leg raises muscles worked during the movement.
Many lifters mistakenly classify this strictly as an abdominal isolation exercise. While it certainly torches the core, the biomechanics are far more complex. To get the most out of this move—and spare your lumbar spine—you need to understand exactly what is contracting and why.
Key Takeaways: Muscles Targeted
- Iliopsoas (Hip Flexors): The primary mover responsible for lifting the legs from the floor.
- Rectus Abdominis: Acts isometrically to stabilize the pelvis and prevent the lower back from arching.
- Rectus Femoris (Quadriceps): Assists in hip flexion and keeping the legs straight.
- Obliques: Provide rotational stability to keep the torso grounded.
- Adductors: Engaged if you actively squeeze your legs together during the lift.
The Primary Movers: It’s Not Just Abs
When analyzing what muscles do lying leg raises work, we have to look at joint function. The main action here is hip flexion—bringing your legs toward your torso. This means the heavy lifting is actually done by the hip flexors, specifically the iliopsoas.
The Role of the Iliopsoas
The iliopsoas is a deep muscle group connecting your spine and pelvis to your femur. When you perform lying leg lifts muscles worked include this powerful group significantly. If your abs aren't strong enough to counteract the pull of the psoas, your pelvis tilts forward, causing that nasty lower back arch.
The Rectus Femoris
This is the only quadricep muscle that crosses the hip joint. If you feel a burning sensation down the front of your thighs, that is the rectus femoris kicking in to assist the lift.
The Core Connection: Isometric vs. Isotonic
So, what do lying leg raises work regarding the abs? Here is the science: your abs are working isometrically. They aren't crunching (shortening) and lengthening significantly; they are fighting to stay rigid.
Their job is to act as a brake. As the heavy weight of your legs lowers, gravity tries to pull your pelvis into an anterior tilt (arching back). Your lower Rectus Abdominis fights to keep the pelvis neutral and the lower back flat against the floor. This is why the exercise is so effective for "lower abs"—not because they lift the legs, but because the leverage requires immense stability at the bottom of the movement.
Variations and Nuances
The Bottom Leg Lift
Some athletes search for the bottom leg lift mechanics, referring to the bottom 20% of the range of motion. This is the hardest part of the rep. The lever arm is longest here, placing maximum torque on the core. If you cannot keep your back flat in this range, you aren't working your abs anymore—you're just straining your spine.
Bent Knee vs. Straight Leg
If you find the lying leg raise muscles worked are predominantly your hips and back, bend your knees. This shortens the lever arm, reducing the load on the hip flexors and allowing the abs to engage without the spine compromising.
My Training Log: Real Talk
I want to be transparent about my history with this movement. Early in my coaching career, I used lying leg raises as a "finisher" for every session. I ignored the warning signs.
I specifically remember the sensation of my hip flexors feeling like tight guitar strings snapping over the bone—a condition often called "snapping hip syndrome." I wasn't controlling the eccentric (lowering) phase. I was just swinging. There was this specific, gritty grinding noise in my left hip socket whenever my heels got within six inches of the floor.
I also recall the specific failure point: my waistband. The moment my lower back lost contact with the mat, my waistband would slide down slightly. That was my tactile cue that my abs had checked out and my spine was taking the load. Once I started stopping the set the moment my waistband shifted, my core actually got stronger, and the hip clicking vanished.
Conclusion
Understanding the lying leg raise muscles worked changes how you execute the rep. It shifts your focus from "lifting the legs" to "stabilizing the spine." Treat this move with respect. It is not just a mindless ab burnout; it is a heavy leverage drill for your entire anterior chain.
Frequently Asked Questions
Do lying leg raises burn belly fat?
No exercise can spot-reduce fat. While lying leg raises strengthen the muscles underneath the fat, revealing them requires a caloric deficit to lower your overall body fat percentage.
Why does my lower back hurt during leg raises?
This usually happens because the abdominal muscles fatigue, causing the pelvis to tilt forward (anterior pelvic tilt). This shifts the tension from the abs to the lumbar spine. To fix this, place your hands under your glutes or reduce the range of motion.
Are hanging leg raises better than lying leg raises?
Hanging raises are generally more advanced and allow for a greater range of motion. However, lying leg raises are better for teaching pelvic stability because the floor provides tactile feedback for your lower back position.
