How to Do an Abdominal Crunch: Proper Form, Variations, and Common Mistakes

Verywell / Ben Goldstein

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Targets: Abdominals

Level: Beginner

Crunches have been the mainstay of ab workouts for decades. They target the rectus abdominis, the six-pack muscle that runs along the front of the torso. Building this muscle is part of developing your core muscles for stability and performance. Crunches can be part of a core strength workout or a total body workout.

How to Do an Abdominal Crunch

Lie down on the floor on your back and bend your knees, placing your hands behind your head or across your chest. Some people find that crossing the arms over the chest helps them avoid pulling on the neck.

  1. Brace your core.
  2. Crunch your ribs toward your pelvis using your abdominal muscles to initiate and complete the movement.
  3. Exhale as you come up and keep your neck straight, chin up.
  4. Hold at the top of the movement for a few seconds, breathing continuously.
  5. Lower slowly back down, but don't relax all the way.
  6. Repeat for 15 to 20 repetitions with perfect form for each rep.

If you find your neck strains too much, you can keep one hand cradling the head. If you put your hands behind your head, your fingers should gently cradle your head. The idea is to support your neck without taking away from the work of your abs.


Crunches work the muscles on the front of your abdomen called the rectus abdominus, which are also known as the six-pack muscles. The rectus abdominis muscle flexes to bring your shoulders towards your hips.

As one of the major core muscles, it provides stability for the body. A strong back and abs are the foundation of your daily movements and sports performance. As well, a strong core is imperative for preventing back pain and strain and promoting spinal and pelvic stability.

Other Variations of an Abdominal Crunch

You can perform this exercise in different ways to meet your skill level and goals.

Full Crunch

  1. Lay on your back and brace your core. 
  2. Bring your shoulder blades 1 or 2 inches off the floor imagining you are bringing your ribs toward your pelvis; bring your knees in at the same time you lift your upper body off the floor.
  3. Exhale as you come up and keep your neck straight, chin up.
  4. Hold at the top of the movement for a few seconds, breathing continuously.
  5. Lower slowly back down without fully relaxing.
  6. Repeat for 15 to 20 repetitions with perfect form for each rep.

Exercise Ball Crunch

  1. Place your upper to mid back on an exercise ball with your feet flat on the floor.
  2. Engage your abs and crunch your ribs toward your pelvis bones using your abdominal muscles
  3. Hold the crunch at the top for a count before slowly lowering back down over the ball.

Common Crunch Variations

  • Bicycle crunch exercise: This ab exercise generally ranks at the top of the list of best ab exercises if done properly.
  • Vertical leg crunch: This version can be a challenge for the lower back if done improperly; make sure you do it right by having a trainer check your form.
  • Long arm crunch: This exercise is another version of a favorite exercise that almost anyone can start doing.
  • Reverse crunch: Get some extra challenge by kicking up the feet with the torso holding steady.
  • Crossover crunch: This exercise is especially good for the obliques.

Common Mistakes

Performing crunches correctly is more complex than it looks. Avoid these errors so they can be as effective as possible.

Pulling on the Neck

This not only strains the neck, but it takes away from working your abs. You want to originate the movement in your abs, not from your head. Place your fist under your chin to keep your neck in proper alignment and not moving.

Crunching Too High

The crunch is a subtle movement, lifting the shoulder blades just a few inches off the floor. Jerking the shoulders up adds momentum and reduces the effectiveness of the exercise. It takes time to build strength in the abs, so it's best to take your time and complete the move slowly rather than using momentum to get the body up.

Relaxing Down to the Floor

It's easy to let your shoulders fall to the floor, but a more effective approach is to keep the tension on the abs throughout the entire movement. You never want to relax your shoulders onto the floor completely.

Back Arch

In the past, it was recommended to keep your back flat against the floor throughout the entire movement. Now it is believed it is better to keep a neutral spine. That means your spine is in the strongest position to support you.

A quick way to find it is to rock the pelvis back and then forward and then allow your pelvis to relax somewhere between those two extremes. If your back arches too much, your abs may need time to build strength. Try propping your feet on a step or platform to support your back.

Safety and Precautions

If you have back or neck problems, talk to your doctor or physical therapist about whether crunches are appropriate. If not done with proper form, they can compress the spine and stress the neck. You may need to avoid crunches after the first trimester of pregnancy, and postpartum if you have diastasis recti. Speak to your healthcare provider for more information.

Try It Out

Incorporate this move into one of these popular workouts:

3 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Frizziero A, Pellizzon G, Vittadini F, Bigliardi D, Costantino C. Efficacy of core stability in non-specific chronic low back painJ Funct Morphol Kinesiol. 2021;6(2):37. doi:10.3390/jfmk6020037

  3. Evenson KR, Barakat R, Brown WJ, et al. Guidelines for physical activity during pregnancy: Comparisons from around the world. Am J Lifestyle Med. 2014;8(2):102-121. doi:10.1177/1559827613498204

By Paige Waehner, CPT
Paige Waehner is a certified personal trainer, author of the "Guide to Become a Personal Trainer," and co-author of "The Buzz on Exercise & Fitness."