Exercise guide
Seated 8 Leg Crunch
- Intermediate
- Compound
- Rep-based
- Waist
The Seated 8 Leg Crunch is a dynamic core exercise that targets the lower abdominals and hip flexors while using a figure-eight motion to engage the obliques and adductors. It builds exceptional rotational stability and coordination by forcing the core to stabilize against the shifting weight of the legs.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Sit on the long edge of a flat bench with your legs extended and feet together.
- Grip the edges of the bench just behind your hips for support and lean your torso back to a 45-degree angle.
- Lift your legs off the ground, keeping a slight bend in the knees and your core tightly braced.
How to do it
- Inhale to brace your midsection, then exhale as you begin 'drawing' a large horizontal figure-eight (infinity symbol) in the air with your feet.
- Move your legs in a fluid, controlled arc up and over to one side, down through the center, and then up and over to the opposite side.
- Maintain a steady tempo, ensuring your torso remains as still as possible while your legs move.
- Complete half your reps in one direction, then reverse the figure-eight pattern for the remaining reps.
Form checklist
- Keep your lower back slightly rounded or neutral; do not allow it to arch excessively.
- Keep your inner thighs squeezed together to maintain tension in the adductors.
- Ensure the movement is driven by the hips and core rather than just swinging the feet.
- Keep your shoulders down and away from your ears to avoid neck strain.
Pro tips
- To maximize oblique recruitment, focus on making the 'loops' of the eight as wide as possible while keeping your chest facing forward.
- Point your toes and squeeze your quads to create full-body tension, which helps stabilize the pelvis during the lateral movements.
Make it harder
- Hold a light dumbbell or medicine ball between your feet to increase the resistance on the hip flexors and lower abs.
- Perform the movement with your hands off the bench, reaching them out to the sides to remove the stability of the arm support.
Frequently asked
- What muscles does the seated 8 leg crunch work?
- The seated 8 leg crunch primarily targets the abs, adductors, and obliques, and also works the erector spinae as secondary muscles.
- What equipment do you need for the seated 8 leg crunch?
- The seated 8 leg crunch requires no equipment — just your body weight.
- Is the seated 8 leg crunch good for beginners?
- The seated 8 leg crunch is rated intermediate. Build a base with simpler variations first, then progress to it with light load and strict form.
Related exercises
- Criss Cross Leg RaisesIntermediate · abs, adductors, and obliques
- Front Plank To Toe TapIntermediate · abs, adductors, erector spinae, hamstrings, obliques, pectorals, and trapezius
- Kneeling Forward Hip CirclesBeginner · abs, adductors, erector spinae, glutes, hip flexors, and obliques
- Lying Abduction Leg Raise On FloorIntermediate · abs, adductors, and obliques