Sit-Up
The sit-up is a bodyweight core exercise where you curl your torso all the way up from lying on your back to sitting upright, using your hip flexors and abdominals together. It's one of the oldest core exercises around, and it still works as a simple way to build the strength to get your torso off the ground with control, whether that's for sport, for getting up off the floor, or just for training your midsection without equipment.
Why it works
Your abdominals contract to curl your spine, while your hip flexors take over for the second half of the movement, pulling your torso up and over your hips. Training this full range, rather than only the crunch portion, builds strength through the whole motion of sitting up, which is a movement you repeat dozens of times a day getting out of bed, off a couch, or up from the floor. Because the resistance is only your own body weight, the exercise scales naturally with your own strength: your first rep and your five-hundredth rep use the same technique, just at different levels of control.
Set up
- Lie on your back with your knees bent and feet flat on the floor.
- Cross your arms over your chest or rest your fingertips lightly by your ears.
- Keep your feet flat and, if needed, hook them under something sturdy for support.
- Engage your core before you move, rather than starting from a completely relaxed position.
How to do it
- Brace your abdominals as if you're about to be tapped in the stomach.
- Curl your chin toward your chest and lift your shoulders off the floor.
- Continue curling your torso up and forward until you're sitting fully upright.
- Pause briefly at the top without throwing your body forward.
- Reverse the motion, lowering your torso back down one vertebra at a time.
- Let your shoulders touch the floor lightly before starting the next rep.
Form cues
- Curl up, don't yank up.
- Keep your chin tucked slightly, not jutting forward.
- Exhale on the way up like you're blowing out a candle.
- Lower with the same control you used to rise.
Breathing: Exhale as you curl up toward sitting, and inhale as you lower back down to the floor.
Common mistakes
Pulling on your neck with your hands to yank yourself up.
Fix: Rest your fingertips lightly by your ears and let your abdominals do the lifting.
Using momentum to swing up instead of curling.
Fix: Slow the rep down until you can feel your abs working through the first few inches off the floor.
Letting the lower back slam into the floor on the way down.
Fix: Lower under control and let your back touch down softly, one section at a time.
Holding your breath through the entire rep.
Fix: Exhale as you rise and inhale as you lower, so your core has a steady rhythm to work with instead of tensing against held air.
How to program it
- Since this is an unloaded core movement rather than a heavy compound lift, 3 sets of 10 to 15 reps most days it's programmed is realistic for most people.
- It pairs well with a rotational or anti-extension core move, like a plank, so your midsection gets trained from more than one angle in the same session.
- Two to three times a week works for most people, since the main limiter here is technique and control rather than heavy fatigue.
Safety notes
- Skip sit-ups on days your lower back is already irritated, since the hip flexor pull can load the lower back if form breaks down.
- Keep the motion slow enough to stop at any point instead of relying on momentum to finish the rep.
- If you feel the movement mainly in your neck instead of your abs, stop and reset your hand position.
Exercise profile
- Force
- Pull
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
How many sit-ups should I do a day?
Three sets of 10 to 15 controlled reps, two to three days a week, is a solid amount for most people; more reps done sloppily add less than fewer reps done with good form.
Are sit-ups bad for your back?
Sit-ups are safe for most people when the motion is slow and controlled and the lower back doesn't slam into the floor. If you already have lower back pain, talk with a professional before adding them.
What's the difference between a sit-up and a crunch?
A crunch lifts just your shoulders and upper back off the floor, while a sit-up continues all the way up to a full sitting position, which brings the hip flexors into the movement.
Can I do sit-ups without anchoring my feet?
Yes. Keeping your feet free makes your abdominals work harder to control the movement, since you can't lean on your hip flexors pulling against anchored feet as much.
Why do sit-ups get easier the more I do them?
As your abdominals and hip flexors get stronger, the same bodyweight resistance takes less relative effort, which is a normal sign of progress and a good time to add reps or slow the tempo.