Waist Exercise · Stability Ball

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Crunch (on Stability Ball, Arms Straight)

Extending the arms overhead on a stability ball crunch turns the torso into a longer lever, so the abs have to work harder to move the same distance. It also removes the option of swinging the arms to build momentum, which is how a lot of people cheat the standard version. Expect this to feel noticeably harder than the crossed-arms version even though the movement looks nearly identical.

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Category

Waist

Equipment

Stability Ball

Target

Abs

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Exercise reference published by PlanWorkouts; see our editorial standards.

How to Do the Crunch (on Stability Ball, Arms Straight)

1. Sit on a stability ball with feet flat on the floor and knees bent to about 90 degrees.
2. Recline back onto the ball until your lower back is supported and your torso is roughly parallel with the floor.
3. Rest your hands behind your head or cross them over your chest.
4. Brace your abs and raise your upper body off the ball, curling your shoulders toward your hips.
5. Hold briefly at the top, then lower back down under control to the starting position.
6. Repeat for your target rep goal, keeping your core engaged and avoiding any reliance on momentum.

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 Crunch (on Stability Ball, Arms Straight) 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 stability ball? These target the same abs with different equipment.

Arms Overhead Full Sit-Up (male) Body Weight · Abs Assisted Hanging Knee Raise Assisted · Abs Assisted Motion Russian Twist Medicine Ball · Abs Band Alternating V-Up Band · Abs

FAQ

What muscles does the Crunch (on Stability Ball, Arms Straight) work?

The Crunch (on Stability Ball, Arms Straight) 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 Crunch (on Stability Ball, Arms Straight)?

You do the Crunch (on Stability Ball, Arms Straight) with a stability ball. 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 Crunch (on Stability Ball, Arms Straight)?

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 Crunch (on Stability Ball, Arms Straight)?

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 Crunch (on Stability Ball, Arms Straight)?

The Arms Overhead Full Sit-Up (male) trains your abs with body weight and a similar movement pattern. Review its form guide before substituting it, since setup and range of motion can differ.