3/4 Sit-Up

3/4 Sit-Up trains the abdominal muscles by bringing the rib cage and pelvis closer together through a controlled range.

Primary muscle

Abs

Primary musclesRectus abdominis

Secondary musclesInternal and external obliques, Iliopsoas

Equipment

Bodyweight

How to perform 3/4 Sit-Up

Follow the sequence in order, paying attention to the starting position, movement path, and finish described in each step.

Lie on the back with the knees bent, feet planted, and arms crossed over the chest or reaching forward.
Brace the abdomen and begin by curling the ribs toward the pelvis without pulling on the head.
Continue into the sit-up until the torso reaches roughly three quarters of the way to upright, stopping before the hip flexors pull you fully vertical.
Pause briefly at the three-quarter position while the feet and pelvis remain still.
Lower the spine under control until the shoulders return to the floor, then reset before the next repetition.

Support the head lightly or cross the arms; the abdominals should move the rib cage.

Keep the arms still to avoid using momentum, let the abdominal muscles move the rib cage toward the pelvis.

Begin by bringing the ribs toward the pelvis rather than simply sitting upright with the hip flexors.

Lower the spine or torso gradually and keep tension through the longest position.

Pulling on the neck: Support the head lightly or cross the arms; the abdominals should move the rib cage.
Moving through the hips only: Begin by bringing the ribs toward the pelvis rather than simply sitting upright with the hip flexors.
Stop when the exercise produces sharp, catching, radiating, or increasing joint pain rather than the expected muscular effort.
Alternative Short-range abdominal crunch: Lift only the head and shoulder blades while the pelvis and feet remain supported.

Place 3/4 Sit-Up after the main compound lifts, in a focused core block, or beside an exercise that does not require a fresh trunk.

Use two to four times per week while accounting for trunk work already supplied by squats, hinges, carries, and overhead lifting.

Goal	Sets	Reps or time	Rest	Effort and execution
Control / technique	2–3	5–8 reps	45–75 sec	Stop well before position changes
Strength / endurance	2–4	8–15 reps	60–90 sec	Stop while 1–3 good-form reps are still possible

Use 3/4 Sit-Up after Barbell Back Squats, Deadlifts, or another main compound lift.
Pair it with Bird Dog or Cable Pallof Press to combine trunk flexion with stability work.

Scale the movement