Reverse Crunch with Straight Leg
The reverse crunch with straight leg is an advanced bodyweight core exercise that performs the reverse crunch with legs fully extended. The straight-leg position increases the lever arm, significantly raising the demand on the lower abs and hip flexors compared to the bent-knee variation.
How to do it
- Lie flat on your back with your arms at your sides and legs extended straight toward the ceiling.
- Engage your lower abs and curl your hips off the floor, pressing your legs upward.
- Hold at the top briefly, then slowly lower your hips back to the floor.
- Keep your legs straight throughout the entire movement.
- Repeat for the desired number of repetitions.
Form cues
- Keep your legs completely straight and extended upward.
- Press your lower back firmly into the floor before you begin.
- Lift your hips using your abdominal strength, not momentum.
- Lower your legs back down slowly and with control.
Breathing: Exhale as you lift your hips upward, and inhale slowly as you lower your legs back to the starting position.
Common mistakes
- Swinging the legs up uses momentum instead of muscle, which reduces the work done by your abs.
- Arching the lower back off the floor puts unnecessary strain on your spine and hip flexors.
- Bending the knees shortens the lever arm, making the exercise easier than intended.
Muscles worked
Primary: abs. Secondary: hip flexors, lower back.
Suggested sets & reps
Get fitter
3 sets × 10–12 reps, rest 60 s
Lose weight
3 sets × 10–15 reps, rest 60 s
Build muscle
3–4 sets × 8–12 reps, rest 90 s
Easier, harder & alternatives
Make it easier
Take care if…
- If you feel sharp lower back pain, ease off and choose a gentler option.
General educational guidance, not medical advice. Stop on sharp pain and check with a qualified professional if unsure.
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Start free →Frequently asked questions
Why do I feel this in my lower back instead of my abs?
If your lower back arches away from the floor, your spine loses support. Focus on pressing your lower back flat into the ground throughout the entire movement.
Can I bend my knees if my legs are too heavy?
Yes, bending your knees shortens the lever arm and makes the movement easier. You can try the standard reverse crunch as a gentler alternative.
How many times a week should I do this exercise?
Two to three times a week with at least one rest day between sessions is plenty for recovery and core strengthening.