Core · Bodyweight
Single Leg Extension Crunch
How to do the single leg extension crunch, the muscles it works, and the mistakes to avoid. Pulled straight from the Kovo app's exercise library.
- Equipment
- Bodyweight
- Difficulty
- Beginner
- Logged as
- Weighted reps
- Movement
- Flexion
- Mechanic
- Isolation
How to do it
Lie on your back with your hands behind your head and your knees bent. Crunch your upper body up while simultaneously extending one leg straight out, then return and repeat, alternating legs each rep.
- 1Feel your abs contract as you lift your shoulders off the floor
- 2Extend the leg fully while keeping your lower back pressed down
- 3Exhale and squeeze your core at the top of each crunch
Common mistakes
- Don't pull on your neck with your hands
- Avoid letting your lower back arch off the floor as the leg extends
- Don't use momentum; control the lift and the return
Muscles worked
The single leg extension crunch mainly works the upper abs and lower abs, with the hip flexors, obliques, and quads assisting.
- Upper AbsPrimary
- Lower AbsPrimary
- Hip FlexorsSupport
- ObliquesSupport
- QuadsSupport
Kovo programs the single leg extension crunch for you and tracks it every session.
We build your whole program, drop the right lifts into each workout, and adjust your weights as you get stronger. Free on iOS and Android.
More abs & core exercises
- How to do the ab wheel rollout
- How to do the ankle tap plank
- How to do the ankle taps
- How to do the resistance band dead bugs
- How to do the resistance band pallof press
- How to do the rollout
Last reviewed June 2026.