Core · Bodyweight
Alternate Bent Leg 45 Degrees Extension
How to do the alternate bent leg 45 degrees 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
- Weighted reps
- Movement
- Flexion
- Mechanic
- Isolation
How to do it
Lie on your back with knees bent and feet off the floor at about 45 degrees. Extend one leg out at a 45-degree angle while keeping your lower back flat, then return and alternate legs.
- 1Lower abs bracing as each leg extends out
- 2Lower back pinned to the floor the whole time
- 3Controlled tempo as you switch legs
Common mistakes
- Letting the lower back arch off the floor
- Dropping the extended leg too low and losing tension
- Rushing the alternation with momentum
Muscles worked
The alternate bent leg 45 degrees extension mainly works the lower abs, upper abs, and hip flexors, with the obliques assisting.
- Lower AbsPrimary
- Upper AbsPrimary
- Hip FlexorsPrimary
- ObliquesSupport
- QuadsMinor
Kovo programs the alternate bent leg 45 degrees 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.