Leg raises are a foundational bodyweight exercise widely incorporated into fitness routines to build strength and stability throughout the core. This movement, typically performed while lying on the back, effectively develops the musculature that controls the pelvis and lumbar spine. The exercise is a popular choice for targeting the lower portion of the abdominal muscles. Mastering the leg raise requires understanding the interplay between the deep core muscles and the powerful muscles responsible for lifting the legs.
Primary Muscles Activated
The primary function of the leg raise is lifting the legs, a movement that heavily relies on the hip flexors. These muscles, particularly the iliopsoas group and the rectus femoris (one of the quadriceps muscles), are the main drivers that shorten to bring the legs toward the torso. The true challenge of the leg raise, however, lies in the work of the abdominal muscles, which act as stabilizers.
The rectus abdominis, commonly known as the “six-pack” muscle, works isometrically to prevent the pelvis from tilting forward as the weight of the legs increases the lever arm. The obliques and the deeper transverse abdominis engage to maintain a rigid, stable core structure. Without this stabilization, the lower back would arch off the floor, shifting the tension away from the abdominals and placing strain on the lumbar spine.
Step-by-Step Execution and Proper Form
To begin the supine leg raise, lie flat on your back with your legs straight and your hands placed palms-down underneath your lower back or flat by your sides for stability. Initiate the movement by performing a slight posterior pelvic tilt, pressing your lower back firmly into the floor or mat. This engagement ensures the core is active before the legs move.
With your legs straight or slightly bent to reduce the leverage, exhale slowly as you raise your legs toward the ceiling in a controlled, deliberate manner. The goal is to lift the legs until they are perpendicular to the floor, or slightly higher, without allowing the lower back to peel away from the ground. Maintaining firm contact between the lumbar spine and the floor is the most important aspect of proper form.
The eccentric or lowering phase of the movement must be performed with great control. Inhale slowly as you return your legs toward the starting position, stopping the descent just before your lower back begins to arch. If you allow your legs to drop too quickly or use momentum, the hip flexors will take over, and the stabilizing work of the abdominal muscles will be lost.
Modifications and Progression
The leg raise can be adjusted to suit any strength level by changing the length of the lever arm or the body’s position. For individuals who find the straight-leg version too challenging, the bent-knee raise, or knee tuck, is an excellent modification. Bending the knees shortens the lever, significantly reducing the load and making it easier to maintain lumbar stability.
Another modification is the short-range-of-motion leg raise, where the legs are only lowered halfway before being brought back up. This technique ensures the core remains engaged and prevents the lower back from arching, which typically happens near the floor. You can gradually increase the range of motion as your core strength improves.
For those looking to advance the exercise, straightening the legs fully during the movement increases the lever arm, demanding greater core strength to stabilize the pelvis. A significant progression is the hanging leg raise, where the body is suspended from a pull-up bar. This variation requires additional grip and upper body strength while forcing the core to work harder to control the body’s swing and lift the legs against gravity.
Adding ankle weights or holding a dumbbell between the feet introduces external resistance, which increases the intensity of both the concentric and eccentric phases. Alternatively, elevating the torso on a decline bench allows the legs to travel through a greater range of motion, increasing the time under tension for the abdominal muscles.