Core · Bodyweight
Lying 90 Degrees Alternate Leg Extension
How to do the lying 90 degrees alternate leg extension, the muscles it works, and the mistakes to avoid. Pulled straight from the Kovo app's exercise library.
- Equipment
- Bodyweight
- Difficulty
- Intermediate
- Logged as
- Reps
- Movement
- Flexion
- Mechanic
- Isolation
How to do it
Lie on your back and lift both legs so hips and knees are bent at 90 degrees. Extend one leg straight out without letting it touch the floor, then bring it back to 90 degrees and alternate with the other leg.
- 1Feel your lower abs working to keep your pelvis stable as the leg extends
- 2Keep your lower back pressed into the floor the whole time
- 3Control the leg out and back without letting it drop
Common mistakes
- Don't let your lower back arch off the ground
- Don't extend so low that you lose core tension
- Don't swing the leg with momentum
Muscles worked
The lying 90 degrees alternate leg extension mainly works the lower abs and hip flexors, with the upper abs, obliques, and quads assisting.
- Lower AbsPrimary
- Hip FlexorsPrimary
- Upper AbsSupport
- ObliquesSupport
- QuadsSupport
- HamstringsMinor
- Tibialis AnteriorMinor
Kovo programs the lying 90 degrees alternate leg extension 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.