
Lying along a flat bench with your legs hanging off the end, you draw your knees toward your chest and let the tailbone lift at the finish. The bench is what makes it work: your legs can drop below hip level, so the abs start from a stretched position instead of a dead hang of slack.
Set up first, then execute. Every cue below is something you can check on your next set.
Breathing & tempo — Exhale hard as the knees come in and the pelvis tucks, inhale on the way out. Two seconds in, one-second hold, three seconds out.
Where to start, and what to change when it stops being hard.
Bodyweight to start. Once you can do 20 clean reps with a visible tailbone lift, add load before adding reps: a 2-5 kg dumbbell squeezed between the feet, or ankle weights. Straightening the legs on the way out is itself a load increase — the longer lever roughly doubles the demand.
The errors that show up most often, and the cue that fixes each one.
Add a deliberate pelvic tuck at the top of each rep. Put a hand under your lower back for one set — if the pressure never changes, you are only flexing hips.
Rest the hands lightly on the bench edge instead of gripping hard, and slow the tempo to 2 seconds in, 3 seconds out. If the legs will not move without the pull, bend the knees more.
Cut the bottom range short — stop the legs at a 30-degree hang rather than fully down — until you can keep the ribs pinned for every rep.
Cap the set at the last rep where the tailbone still clears the bench. Once it stops lifting, the set is over regardless of how the reps feel.
Most of the movement is hip flexion, which the psoas does whether your abs help or not. The part that pays is the last few degrees, where your tailbone leaves the bench and the pelvis tilts back under you. That short range is rectus abdominis working against the weight of both legs, and it is the only bit worth being fussy about.
Doing it on a bench rather than the floor buys you extra range at the bottom. Your heels can hang 20-30 cm below the bench surface, so the abs are loaded before the rep even starts. On the floor the legs bottom out and the first third of every rep is free.
End of a session, after the compound work, two or three times a week. It pairs badly with anything else that hammers the hip flexors on the same day — heavy front squats or sprints leave the psoas fried and you will feel this in your hips rather than your stomach. Pair it with a rollout or a cable crunch instead.
No kit, too hard, or too easy — here's where to go instead.
The rectus abdominis is one sheet of muscle and it contracts along its whole length; you cannot train a lower half separately. What is true is that lifting the pelvis loads the fibres below the navel harder than a standard crunch does, so it feels lower. Treat it as a different pull on the same muscle, not a separate muscle.
Because you are stopping the rep before the abs get involved. Hip flexion up to about 90 degrees is psoas work. Keep going until the tailbone lifts off the bench and pause there. If the tailbone will not lift, drop to a shorter lever by pulling the knees in tighter.
Bench, if you have one free. The extra range below hip level loads the abs at length, which is where most of the growth stimulus in any muscle lives. The floor version is fine when the gym is busy, but expect to need more reps for the same effect.
No. Abdominal work thickens the muscle; it does nothing to the fat over it, and there is no such thing as spot reduction. Train the abs because a strong braced trunk carries your squats and deadlifts, and handle the fat with your diet.