The leg lift is a foundational exercise for developing core and hip strength. This dynamic movement uses muscular force to lift the lower body against gravity. It primarily challenges the body’s ability to maintain a stable, neutral spine while controlling the heavy lever of the legs. Training the body to control the pelvis and lumbar spine translates to better stability in everyday movements and other exercises.
Anatomical Focus of the Exercise
The primary muscles responsible for lifting the legs are the hip flexors, particularly the iliopsoas group. The iliopsoas connects the lumbar spine and pelvis to the femur, making it the main engine for bringing the thigh closer to the torso. Because the legs act as a long, heavy lever, the hip flexors must generate significant force to elevate them, especially when the legs are kept straight.
The challenge of the leg lift lies in the secondary role of the abdominal muscles. The rectus abdominis and the deeper transverse abdominis must contract isometrically to prevent the lower back from arching away from the floor. This stabilization counteracts the strong pull exerted by the hip flexors on the lumbar vertebrae. If the core stabilizers fail, the pelvis tilts anteriorly, causing the lower back to excessively arch, which shifts the stress onto the spine.
Proper Technique for Ground Leg Lifts
Begin by lying supine on a mat with both legs extended straight. Place your arms along your sides with palms pressed into the floor for support. Before initiating the lift, actively draw your navel toward your spine to flatten your lower back against the mat. This ensures the core is engaged in a posterior pelvic tilt, protecting the lumbar spine throughout the movement.
Start the movement by slowly raising your legs, keeping them straight and together, until they point toward the ceiling. The ascent should be controlled and deliberate, relying on the hip flexors and deep core muscles rather than momentum. At the top position, the body forms an “L” shape, and the focus remains on keeping the back flat.
The lowering phase maximizes core engagement and must be executed with greater control than the lift. Slowly lower the legs back toward the floor, maintaining pressure of the lower back against the mat for as long as possible. Stop the descent when your heels are about six inches from the floor, or immediately if your lower back begins to arch or lift. This slow, controlled eccentric contraction increases time under tension, strengthening the core stabilizers.
Avoiding Strain and Modifying Difficulty
The failure to maintain a flat lower back is the most common error and source of strain, resulting in hyperextension of the lumbar spine. To mitigate this risk, beginners should place their hands, palms down, underneath the lower back or tailbone for additional support. This hand placement cues the necessary posterior pelvic tilt and prevents the back from arching.
To reduce leverage and make the exercise easier, modify the movement by performing a bent-knee leg raise. Bending the knees shortens the lever arm, decreasing the load on both the hip flexors and the abdominal muscles. You can also perform single-leg raises, alternating between legs, which further decreases the stabilization demands on the core.
When the standard leg lift is mastered, difficulty can be increased by extending the range of motion, lowering the legs closer to the floor, or performing an extended hold at the bottom. More advanced variations, such as the hanging leg raise, remove floor support. These require the core to stabilize the entire body against gravity while the legs are lifted. These progressions should only be attempted once the ability to keep the lower back stable on the ground is established.