Waist Exercise · Body Weight

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Quarter Sit-Up

The quarter sit-up shortens the range dramatically compared to a full sit-up, keeping tension on the abs through a small arc rather than involving the hip flexors as heavily as a full sit-up does. It's a way to isolate the upper abs more directly.

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Category

Waist

Equipment

Body Weight

Target

Abs

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Exercise reference published by PlanWorkouts; see our editorial standards.

How to Do the Quarter Sit-Up

1. Lie back on the floor with knees bent and feet flat.
2. Clasp your hands behind your head, elbows pointing out to the sides.
3. Squeeze your abs to raise your upper body off the floor, curling up until your torso reaches about 45 degrees.
4. Hold briefly at the top of the curl, then lower yourself back down slowly.
5. Repeat for your planned rep target, maintaining clean technique and steady breathing on every repetition.

Technique & Form Tips

Focus on trunk flexion, rotation, or anti-movement stability as required by your specific variation. Maintain the suggested pelvic and spinal orientation to keep tension focused on the abdominal area throughout each repetition or hold.

Common Mistakes to Avoid

• Copying the wrong trunk action: Follow the demonstrated movement. A held plank, rotation and crunch require different actions rather than the same repeated trunk curl.
• Lower back arching: Keep the spine controlled to prevent the lower back from hyperextending under the load.
• Excessive speed: Perform movements with deliberate control rather than relying on rapid, bouncing motions.

How to Breathe During This Exercise

Maintain a steady breathing rhythm during the effort.

Comfort and Control

Choose a load and range you can control. Stop if the movement causes pain. If discomfort persists, stop and ask a qualified professional about an appropriate exercise and range.

General guidance: Mayo Clinic on weight-training technique. Follow the specific movement steps above for this variation.

Muscles Worked

The Quarter Sit-Up mainly targets your Abs, with your Hip Flexors helping support the movement.

More Waist Exercises

3/4 Sit-Up Body Weight · Abs 45° Side Bend Body Weight · Abs Air Bike Body Weight · Abs Alternate Heel Touchers Body Weight · Abs Arm Slingers Hanging Bent Knee Legs Body Weight · Abs Arm Slingers Hanging Straight Legs Body Weight · Abs

More Abs Exercises

Arms Overhead Full Sit-Up (male) Body Weight · Abs Assisted Hanging Knee Raise Assisted · Abs Assisted Hanging Knee Raise With Throw Down Assisted · Abs Assisted Lying Leg Raise With Lateral Throw Down Assisted · Abs Assisted Lying Leg Raise With Throw Down Assisted · Abs Assisted Motion Russian Twist Medicine Ball · Abs

Equipment Alternatives

Don't have body weight? These target the same abs with different equipment.

Assisted Hanging Knee Raise Assisted · Abs Assisted Motion Russian Twist Medicine Ball · Abs Band Alternating V-Up Band · Abs Barbell Press Sit-Up Barbell · Abs

FAQ

What muscles does the Quarter Sit-Up work?

The Quarter Sit-Up mainly works your abs. Your hip flexors also works to help support and steady your body. Using good, smooth form makes sure you work the right muscles and avoid unnecessary strain on your joints.

What equipment do I need for the Quarter Sit-Up?

You do the Quarter Sit-Up with no equipment — just body weight. Make sure your equipment is set up safely before starting. If you work out at home or have limited gear, check out our alternative exercises below.

What form mistake should I watch for on the Quarter Sit-Up?

One mistake to watch for is copying the wrong trunk action: Follow the demonstrated movement. A held plank, rotation and crunch require different actions rather than the same repeated trunk curl.. Use a comfortable range and a controlled return; reduce the load if you cannot maintain the demonstrated setup.

How many sets and reps should I perform on the Quarter Sit-Up?

Use a short set of controlled repetitions, or a manageable hold when the movement is static. Stop when you cannot maintain the demonstrated position. Build control before adding duration, repetitions or resistance; the appropriate amount depends on the exercise and your experience.

What's a good alternative to the Quarter Sit-Up?

The Assisted Hanging Knee Raise trains your abs with assisted and a similar movement pattern. Review its form guide before substituting it, since setup and range of motion can differ.