You want a 45-degree torso raise, not a full sit-up. It uses bodyweight, and you can do it at home or in the gym with your knees bent, feet flat, and hands behind your head.
The movement is centered on the waist, with your abs doing the work and your hip flexors and lower back involved as well.
Setup and Starting Position
Lie flat with your lower back on the ground and set your feet so they stay planted. Keep your hands behind your head and your elbows out so you can curl up cleanly instead of folding inward.
The position should feel stable, with no strain before you start. If your feet slide or your elbows cave in, the rep is already losing shape.
How to Perform the Rep
Curl up until your torso reaches the 45-degree finish, then hold that position briefly. Keep the movement compact and controlled instead of letting it turn into a snap.
Lower back to the starting position under control. If the rep starts to feel like a hinge instead of a curl, the form is slipping.
What Good Repetition Quality Looks Like
A clean rep is controlled, not rushed. You curl up to the 45-degree finish, pause briefly, then lower back down the same way without losing control or changing the base.
The setup should stay fixed: knees bent, feet flat, hands behind the head, elbows out. The movement should come from the abs, not a yank through the hip flexors or a hinge in the lower back.
Each rep should match the last one in start position, top position, and tempo. If a rep snaps up, shortens early, or drops fast on the way down, the control is slipping.
Common Form Errors
The main breakdown is losing the curl shape. The rep should round through the waist; if the torso moves like a hinge, the abs are not driving it.
A second miss is rushing the descent. You want the way down to stay slow and controlled, not collapse back to the floor.
If the finish cuts off early, the rep stops before the torso reaches the intended angle. On video, the chest rises a little and then stalls.
When the hip flexors or lower back take over, the motion gets stiff and the waist stops curling cleanly.
What You Should Feel
You should feel the abs doing the work, not a yank through the neck or a crank through the lower back. The rep should feel like a controlled curl off the floor, with the waist closing as the torso rises to the top.
At the top, the effort should stay tight through the abs. If the hip flexors take over, it starts to feel like the thighs are pulling the torso up instead of the waist doing the lift.
On the way down, you should feel like you are resisting gravity, not dropping back. If the lower back snaps down or the torso loses shape from rep to rep, the repetition is breaking down.
How Corect Reads This Movement on Video
Corect can judge this rep from phone video by checking the visible range, tempo, and consistency across reps.
A clean rep shows a controlled curl to the 45-degree top position, a brief pause, and a steady lower back to the start. It also shows the knees staying bent, the feet staying planted, and the torso finishing in the same place rep after rep.
3/4 Sit-up: the movement, step by step
- Lie flat on your back with your knees bent and feet flat on the ground.
- Place your hands behind your head with your elbows pointing outwards.
- Engaging your abs, slowly lift your upper body off the ground, curling forward until your torso is at a 45-degree angle.
- Pause for a moment at the top, then slowly lower your upper body back down to the starting position.
- Repeat for the desired number of repetitions.
Common questions
How do you set up for the 3/4 sit-up?
Lie flat with your lower back on the ground, knees bent, and feet planted. Keep your hands behind your head with your elbows out so you can curl up cleanly.
How high should you come up on the rep?
Curl up until your torso reaches the 45-degree finish, then hold that position briefly. The movement should stay compact and controlled.
What are the main form errors to watch for?
Common breakdowns include losing the curl shape, rushing the descent, finishing early, or letting the hip flexors and lower back take over.
What should a clean rep look like on video?
A clean rep shows a controlled curl to the 45-degree top position, a brief pause, and a steady return to the start. The knees stay bent, the feet stay planted, and each rep matches the last.
The hardest part of fixing any of this is that you cannot see yourself mid-rep. Corect reads your form from a phone video and shows you what actually happened on each rep of your 3/4 sit-up — depth, bar path, where the breakdown starts. Try it free.
