The lying leg raise is a foundational bodyweight movement focused on strengthening the core, performed while lying on the back. It is a highly effective exercise that requires lifting the legs against gravity, challenging the muscles responsible for hip flexion and spinal stabilization. The primary function of this exercise is to develop strength in the lower abdominal region and the hip flexor complex. This compound nature makes the lying leg raise a comprehensive tool for improving overall core rigidity and functional movement patterns.
Primary and Secondary Muscles Activated
The movement of lifting the legs is initiated by the hip flexor muscles, which act as the primary movers in this exercise. Specifically, the iliopsoas, a deep muscle group connecting the lower back to the femur, and the rectus femoris are heavily engaged. These muscles are responsible for pulling the legs upward toward the ceiling.
While the hip flexors move the legs, the abdominal muscles perform a significant stabilizing role. The rectus abdominis, particularly the lower fibers, works isometrically to prevent the lower back from arching away from the floor. This anti-extension function maintains a stable spine under the load of the moving legs. The oblique muscles and the deeper transverse abdominis also contribute by bracing the torso and pelvis, ensuring the movement is controlled and originates from the core.
Step-by-Step Execution Guide
To begin, lie flat on your back with your legs straight and together. Place your hands flat on the floor beside your hips, or slide them palms-down underneath your glutes for additional support.
Before initiating the movement, consciously engage your core and press your lower back firmly into the floor, establishing a slight posterior pelvic tilt. This bracing action locks the lumbar spine in a safe, neutral position. Exhaling, slowly lift your legs toward the ceiling, maintaining straight knees throughout the ascent.
Continue lifting until your feet are perpendicular to the floor, or until you feel your lower back begin to lift, whichever comes first. The speed of the movement should be controlled and deliberate to maximize time under tension. Inhaling, reverse the motion and slowly lower your legs back toward the floor, maintaining firm core engagement.
The descent should be slower and more controlled than the ascent, as this eccentric phase builds significant core strength. Stop the lowering motion just before your heels touch the ground. This ensures continuous tension on the abdominal muscles without allowing the core to relax.
Form Adjustments and Avoiding Common Mistakes
Arching the lower back, known as lumbar hyperextension, is the most common and potentially dangerous error. This mistake shifts stress away from the abdominal muscles and onto the lumbar spine, which can lead to discomfort or injury. To avoid this, focus intensely on keeping the small of your back pressed into the floor throughout the entire range of motion. Placing your hands underneath your glutes can be a helpful cue for maintaining contact.
Another frequent mistake is using momentum to swing the legs up, which defeats the purpose of controlled muscle contraction. The movement must be slow and deliberate, especially during the lowering phase, to ensure the core is doing the work rather than simply relying on inertia. Allowing the head or shoulders to lift off the ground is also a sign of insufficient core strength.
Modifications
For beginners or those with tight hip flexors, the exercise can be regressed by performing the bent-knee leg raise, where the knees remain bent at a 90-degree angle. This shortens the lever arm, significantly reducing the load on the core and making it easier to maintain a flat lower back. To progress the exercise once the straight-leg version is mastered, perform the movement at a slower tempo or add resistance by holding a light dumbbell between the ankles.