Exercise guide
Lying Bent Knee Figure 8
- Beginner
- Compound
- Rep-based
- Waist
This exercise targets the lower abdominals and hip stabilizers by moving one leg in a controlled figure-8 pattern, enhancing core stability and hip mobility. It is particularly effective for isolating the deep core while improving coordination between the hips and trunk.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back with your legs extended and arms by your sides for stability.
- Bend one knee to a 90-degree angle, lifting the thigh until it is perpendicular to the floor.
- Press your lower back firmly into the mat to engage your core and prevent arching.
- Keep the non-working leg straight and pinned to the floor.
How to do it
- Initiate the movement by drawing a horizontal '8' or infinity symbol in the air with your bent knee.
- Inhale as you move the knee across your body's midline and exhale as you sweep it outward and back to the starting position.
- Move at a slow, deliberate tempo, focusing on smooth transitions between the loops of the 8.
- Complete all repetitions on one side before switching to the other leg.
Form checklist
- Keep your pelvis and lower back glued to the floor; do not let your hips rock.
- Ensure the movement originates from the hip joint rather than just the lower leg.
- Keep the non-working leg completely still and active to maintain balance.
- Maintain a consistent 90-degree bend in the working knee.
Pro tips
- Visualize your lower abdominals acting as an anchor to keep your torso perfectly still while the leg moves.
- Focus on the inner thigh (adductors) as you cross the midline and the glute/hip flexor as you sweep outward.
Make it harder
- Straighten the working leg to increase the lever length and significantly raise the core demand.
- Hover the non-working leg two inches off the ground to force the entire core to work harder.
Frequently asked
- What muscles does the lying bent knee figure 8 work?
- The lying bent knee figure 8 primarily targets the abs and adductors, and also works the erector spinae as secondary muscles.
- What equipment do you need for the lying bent knee figure 8?
- The lying bent knee figure 8 requires no equipment — just your body weight.
- Is the lying bent knee figure 8 good for beginners?
- Yes. The lying bent knee figure 8 is a beginner-friendly movement and a strong foundation to build on.
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 Backward Hip CirclesBeginner · abs, adductors, erector spinae, glutes, and hip flexors
- Kneeling Forward Hip CirclesBeginner · abs, adductors, erector spinae, glutes, hip flexors, and obliques