Exercise guide
Sit Up
- Beginner
- Compound
- Rep-based
- Waist
The sit-up is a fundamental core exercise that targets the rectus abdominis and hip flexors, building functional trunk strength and spinal flexion control.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back on a mat with your knees bent at approximately a 90-degree angle.
- Place your feet flat on the floor, hip-width apart.
- Cross your arms over your chest or place your fingertips lightly behind your ears without pulling on your neck.
How to do it
- Exhale and engage your core to lift your torso off the floor, curling your spine until your chest is near your thighs.
- Maintain a controlled 2-second tempo on the way up, avoiding the use of momentum.
- Inhale as you slowly lower your torso back to the starting position, unrolling your spine one vertebra at a time.
Form checklist
- Keep your feet firmly planted on the floor throughout the entire rep.
- Avoid tucking your chin into your chest; keep a fist-sized gap between chin and sternum.
- Ensure your lower back makes contact with the floor before your shoulder blades on the descent.
- Do not use your arms to swing or generate momentum to lift your body.
Pro tips
- Focus on 'peeling' your spine off the floor segment by segment to maximize abdominal recruitment and minimize hip flexor dominance.
- Pause for a split second at the top of the movement to emphasize the peak contraction of the abs.
Make it harder
- Hold a weight plate or dumbbell against your chest to increase resistance.
- Perform the exercise on a decline bench to increase the range of motion and time under tension.
Frequently asked
- What muscles does the sit up work?
- The sit up primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.
- What equipment do you need for the sit up?
- The sit up requires no equipment — just your body weight.
- Is the sit up good for beginners?
- Yes. The sit up is a beginner-friendly movement and a strong foundation to build on.