Exercise guide
Quarter Sit-Up
- Beginner
- Isolation
- Rep-based
- Waist
The quarter sit-up is a foundational core exercise that isolates the upper rectus abdominis by utilizing a limited range of motion to keep the muscles under constant tension. It effectively builds abdominal strength while minimizing strain on the lower back compared to full sit-ups.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back on a mat with your knees bent and feet flat on the floor hip-width apart.
- Place your hands lightly behind your head without interlacing your fingers, or rest them on your thighs.
- Tuck your chin slightly and press your lower back firmly into the floor to engage your core.
How to do it
- Exhale and contract your abdominals to lift your head, neck, and the tops of your shoulder blades about 3-4 inches off the floor.
- Pause at the top for a one-second peak contraction, focusing on squeezing your ribs toward your hips.
- Inhale as you slowly lower your shoulders back to the starting position using a controlled 2-second tempo.
Form checklist
- Keep your lower back in contact with the floor at all times.
- Lead the movement with your chest, not your chin or neck.
- Avoid using momentum or swinging your arms to lift your torso.
- Keep your feet anchored to the ground throughout the set.
Pro tips
- Focus on the mind-muscle connection by visualizing your abdominal wall shortening as you lift.
- To maximize engagement, do not let your shoulder blades fully rest on the floor between repetitions to maintain constant tension.
Make it harder
- Hold a small weight plate or dumbbell against your chest.
- Perform the exercise with your legs raised in a 90-degree tabletop position to further challenge your stability.
Frequently asked
- What muscles does the quarter sit-up work?
- The quarter sit-up primarily targets the abs, and also works the erector spinae as secondary muscles.
- What equipment do you need for the quarter sit-up?
- The quarter sit-up requires no equipment — just your body weight.
- Is the quarter sit-up good for beginners?
- Yes. The quarter sit-up is a beginner-friendly movement and a strong foundation to build on.