The bent-knee raised leg crunch is a bodyweight abdominal exercise performed lying down with hips and knees bent to 90 degrees, so the abs curl the ribcage toward a fixed pelvis. Bending the knees shortens the leg lever compared with the straight-legraised leg crunch, so the hip flexors work less to hold the legs up and the lower back stays flat for longer sets. The tabletop position also gives you a clear target: knees over hips, shins level, nothing drifting. Beginners use it as their first floor crunch, at the end of a session.
What Muscles Does the Bent-Knee Raised Leg Crunch Work?
- Primary: Rectus abdominis (six-pack)
- Secondary: External and internal obliques
- Tertiary: Iliopsoas (hip flexors), transverse abdominis, deep neck flexors
How Do You Set Up for the Bent-Knee Raised Leg Crunch?
Lie on your back with your arms at your sides. Lift your feet and bend your hips and knees to 90 degrees so your thighs point at the ceiling and your shins are parallel to the floor, ankles together. Press your lower back into the mat until no gap remains under it. Place your fingertips behind your ears or cross your arms over your chest, tuck your chin, and hold the tabletop still.
How Do You Perform the Bent-Knee Raised Leg Crunch?
- Lock the tabletop: knees stacked over hips, shins level, lower back pressed flat.
- Exhale and curl your ribcage toward your pelvis, peeling your head, shoulders and upper back off the floor in that order.
- Stop when your shoulder blades clear the floor and your abs feel fully shortened; your knees have not moved toward your chest.
- Squeeze at the top for one full second with your gaze on your knees, not the ceiling.
- Lower under control over two seconds, laying your upper back, then your shoulders, then your head back down.
- Check the tabletop: pull your knees back over your hips if they drifted, flatten your back, and start the next rep.
What Are the Key Form Cues?
- Curl like a rolling mat: bend the spine one segment at a time instead of hinging from the hips so the abs, not the hip flexors, do the lifting.
- Keep the shins level: if they tilt, the hip flexors are pulling the knees in; treat the tabletop as a wall your ribs curl toward.
- Reach your sternum toward your knees rather than your chin toward the ceiling.
- Let the exhale finish exactly at the top squeeze, then inhale on the way down.
- Keep your elbows wide and your hands light so the arms cannot cheat the curl.
What Are the Most Common Mistakes?
- Pulling the knees toward the chest on each rep: the hip flexors do the work and the lumbar spine flattens under load instead of the abs shortening; freeze the knees over the hips.
- Yanking the head forward with the hands: it strains the neck and lifts the shoulders with arm force; keep the fingertips light and lead with the chest.
- Coming up into a sit-up: once the shoulder blades are well off the floor the hip flexors finish the movement; stop at peak abdominal contraction.
- Letting the lower back arch as the legs tire: the lumbar gap loads the discs on every rep; end the set or rest before it appears.
- Dropping the torso back to the floor: it wastes the eccentric half of the rep; lower over two seconds and touch down lightly.
What Are the Best Bent-Knee Raised Leg Crunch Variations?
- Flat-foot crunch: feet on the floor, knees bent, an easier regression while you learn the curl.
- Raised leg crunch: legs straight and vertical, a longer lever that demands more hip flexor control.
- Bent-knee oblique crunch: one elbow reaches toward the opposite knee to shift the work to the obliques.
- Single-leg tabletop crunch: one leg in tabletop, the other hovering, which adds an anti-rotation demand.
- Dumbbell crunch: the same curl with a dumbbell held on the chest for load.
How Do You Progress the Bent-Knee Raised Leg Crunch?
- Add load only after 15 clean reps: hold a 5 pound plate on your chest and add 5 pounds at a time.
- Build from 10 reps to 20 per set before adding weight.
- Add one set at a time, from 2 up to 4.
- Hold the top for three seconds, or straighten the knees a little to lengthen the lever.
How Should You Program the Bent-Knee Raised Leg Crunch?
Program the bent-knee raised leg crunch at the end of a session as abdominal accessory work, after your compound lifts. Two to three times per week is enough. Do 3 to 4 sets of 12 to 20 reps with 45 to 60 seconds of rest. Pair it with a plank or dead bug so the abs get both flexion and anti-extension work. Keep the tabletop fixed on every rep or end the set.