The leg raise is a foundational bodyweight exercise used to strengthen the midsection. It involves lying on the back and raising the legs off the floor against gravity. This challenging movement is a staple in fitness routines because it requires controlled strength rather than momentum. This guide clarifies the movement and provides steps for safe execution.
Anatomy: Muscles Targeted
The movement of lifting the legs is primarily driven by the hip flexors, including the iliopsoas. The iliopsoas is the strongest of these muscles, connecting the lower spine and pelvis to the femur, making it the main engine for bringing the thighs closer to the torso. While these muscles initiate the lift, the exercise is performed to strengthen the entire abdominal wall.
The rectus abdominis, or “six-pack” muscle, acts as a dynamic stabilizer. Its primary function is to prevent the pelvis from tilting forward, which keeps the lower back from arching away from the floor. This stabilization makes the leg raise an effective core-strengthening movement. The transverse abdominis acts like an internal corset, engaging to brace the midsection and maintain spinal stability throughout the range of motion.
Execution: Step-by-Step Guide
To begin the standard lying leg raise, position yourself flat on your back on a firm surface. Place your arms straight at your sides with palms down, or tuck your hands beneath your lower glutes for minor support. Engage your core muscles slightly to flatten the lower back against the floor.
The concentric phase begins by slowly raising both legs simultaneously, keeping them straight and without using momentum. Continue lifting until the legs are perpendicular to the floor, forming a 90-degree angle with your torso. Focus on contracting the lower abdominal muscles and hip flexors throughout this upward motion.
The eccentric phase, or lowering the legs, is the most challenging and beneficial part of the exercise. Slowly and deliberately lower your legs back toward the floor over a count of three to five seconds. The control during this descent places significant tension on the rectus abdominis. Do not let the heels touch the floor between repetitions, maintaining continuous tension on the working muscles.
Avoiding Lower Back Strain
The primary risk of the leg raise is strain on the lower back caused by the pelvis tipping forward (anterior tilt). To mitigate this, performers must maintain a posterior pelvic tilt, actively pressing the small of the back into the floor. This requires constant engagement of the abdominal muscles throughout the entire set.
If the lower back begins to arch, it signals that the core musculature is no longer strong enough to counteract the leverage created by the descending legs. This leverage increases significantly the further the legs are lowered toward the floor. To prevent arching, the movement must be limited to a safe range of motion where the back remains flat.
The moment you feel the lower back lift off the floor, the descent should stop immediately. For many individuals, this safe range might mean only lowering the legs to a 45-degree angle rather than completely to the floor. Prioritizing spinal stability over a full range of motion ensures the exercise effectively targets the intended muscles.
Progressive Variations
The leg raise can be modified to accommodate various fitness levels, providing a path for progressive overload.
Beginner Modifications
For beginners, the bent-knee leg raise significantly reduces the lever arm, making the exercise easier to control. The single-leg raise also serves as an excellent starting point, allowing the individual to focus bracing effort on stabilizing the core while only one leg moves.
Advanced Modifications
As core strength improves, the challenge can be increased by moving to the hanging leg raise. This variation is performed while suspended from a pull-up bar, removing the floor as support and requiring significant grip strength. The hanging position forces the core to work against gravity in an unsupported environment, dramatically increasing the difficulty. Highly advanced trainees may use a decline bench, allowing the legs to be lowered further below the horizontal plane for an increased range of motion. Alternatively, introducing ankle weights will increase the load on the working muscles.