Exercise guide
3/4 Sit-Up
- Beginner
- Isolation
- Rep-based
- Waist
The 3/4 sit-up targets the rectus abdominis and obliques by maintaining constant tension through a restricted range of motion. By stopping before reaching a full upright position, you prevent the core muscles from relaxing at the top, leading to greater muscle fiber recruitment.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back with knees bent and feet flat on the floor, hip-width apart.
- Place your hands lightly behind your head or crossed over your chest.
- Tuck your chin slightly toward your chest to maintain a neutral cervical spine.
How to do it
- Exhale as you contract your abdominals to lift your torso off the floor in a controlled curling motion.
- Stop the ascent when your torso is at a 45-to-60 degree angle, approximately three-quarters of the way to your knees.
- Inhale as you slowly lower your torso back down, stopping just before your shoulder blades touch the mat.
- Maintain a controlled 2-0-2 tempo (two seconds up, two seconds down) to maximize time under tension.
Form checklist
- Keep your feet flat on the ground throughout the entire movement.
- Avoid pulling on your neck or head with your hands.
- Ensure your lower back remains in contact with the floor during the initial phase of the lift.
- Do not use momentum or 'swing' your body up to complete the rep.
Pro tips
- Focus on the 'rib-to-hip' connection, imagining you are folding your torso like an accordion to engage the deep core.
- Maintain a hard squeeze at the top of the 3/4 range to emphasize the peak contraction of the rectus abdominis.
Make it harder
- Hold a weight plate or medicine ball against your chest to increase resistance.
- Extend your arms straight overhead to increase the lever length and mechanical disadvantage.
Frequently asked
- What muscles does the 3/4 sit-up work?
- The 3/4 sit-up primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.
- What equipment do you need for the 3/4 sit-up?
- The 3/4 sit-up requires no equipment — just your body weight.
- Is the 3/4 sit-up good for beginners?
- Yes. The 3/4 sit-up is a beginner-friendly movement and a strong foundation to build on.