Exercise guide
Lying Alternate Leg Extension
- Beginner
- Isolation
- Rep-based
- Lower legs
This exercise targets the lower abdominals and hip flexors while engaging the quadriceps through active knee extension. It is an effective beginner movement for improving pelvic stability and core coordination without equipment.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back on a mat with your knees bent and feet flat on the floor, hip-width apart.
- Place your arms by your sides with palms down, or tuck your hands slightly under your glutes for extra lower back support.
- Engage your core by pulling your navel toward your spine and pressing your lower back firmly into the floor.
How to do it
- Exhale as you extend one leg straight out until it is fully locked and hovering just a few inches above the floor.
- Inhale as you slowly bend the knee to return the foot to the starting position with control.
- Immediately repeat the movement with the opposite leg, alternating sides in a rhythmic, controlled tempo.
- Maintain a steady pace, focusing on a 2-second extension and a 2-second return.
Form checklist
- Keep your lower back in constant contact with the floor; do not let it arch.
- Ensure the moving leg reaches full extension to maximize quadriceps contraction.
- Keep your neck and shoulders relaxed to avoid unnecessary tension.
- Control the descent of the leg rather than letting gravity drop it.
Pro tips
- Flex your toes toward your shin (dorsiflexion) during the extension to increase tension throughout the entire anterior chain.
- Focus on the 'hollow body' sensation, imagining you are closing the gap between your ribs and hips as you extend the leg.
Make it harder
- Start from a 'tabletop' position with both feet hovering off the floor at a 90-degree angle instead of resting them on the ground.
- Slow the eccentric phase to 4 seconds to increase time under tension for the lower abs.
Frequently asked
- What muscles does the lying alternate leg extension work?
- The lying alternate leg extension primarily targets the abs, and also works the glutes as secondary muscles.
- What equipment do you need for the lying alternate leg extension?
- The lying alternate leg extension requires no equipment — just your body weight.
- Is the lying alternate leg extension good for beginners?
- Yes. The lying alternate leg extension is a beginner-friendly movement and a strong foundation to build on.