FormTwin › Exercises › Sit-Up

What muscles does the Sit-Up work?

The sit-up trains the rectus abdominis through a full trunk flexion, with the hip flexors assisting — a classic bodyweight ab builder.

Primary muscles worked

Secondary muscles worked

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How to do the Sit-Up

  1. Lie on your back, knees bent, feet flat on the floor.
  2. Cross your arms over your chest or lightly cup your head.
  3. Curl your torso up, leading with your ribs toward your hips.
  4. Come up until your chest nears your thighs.
  5. Lower under control back to the floor.

Common mistakes

Variations

CrunchWeighted sit-upDecline sit-up

Frequently asked questions

What muscles do sit-ups work?

Sit-ups mainly work the rectus abdominis (the 'six-pack' muscle), with the hip flexors assisting as you lift the torso and the obliques stabilising. The full range recruits the hip flexors more than a crunch does.

Sit-ups vs crunches — which is better?

Crunches isolate the abs with a short range and less hip-flexor involvement; sit-ups add a fuller range and more hip-flexor work. For the abs alone, crunches are cleaner; sit-ups build more overall trunk endurance.

Do sit-ups burn belly fat?

Not directly — no exercise spot-reduces fat. Sit-ups strengthen the muscles underneath, but a visible six-pack comes from lowering overall body fat through diet and training.

Related exercises

DeadliftBack SquatBench PressPull-UpPush-Up

This guide is general fitness information, not medical advice. Muscle involvement varies with form, grip and individual anatomy. Consult a professional before starting a new program.