Crunch (exercise)

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Performing the crunch

The crunch is one of the most popular abdominal exercises. When performed properly, it engages all the abdominal muscles but primarily it works the rectus abdominis muscle and the obliques. It allows both building six-pack abs, and tightening the belly. Crunches use the exerciser's own body weight to tone muscle, and are recommended as a low-cost exercise that can be performed at home.[1]


In a crunch, the lower back does not lift off the floor

The biomechanics professor Stuart McGill was quoted in The New York Times Health blog as stating:

An approved crunch begins with you lying down, one knee bent, and hands positioned beneath your lower back for support. "Do not hollow your stomach or press your back against the floor", McGill says. Gently lift your head and shoulders, hold briefly and relax back down.[2]

In a crunch, unlike a sit-up, the lower back stays on the floor. This is said to eliminate any involvement by the hip flexors, and make the crunch an effective isolation exercise for the abdominals.[3]

See also[edit]


  1. ^ "Exercising on a budget". MedlinePlus Medical Encyclopedia. Retrieved 20 April 2020.
  2. ^ Reynolds, Gretchen (17 June 2009). "Is Your Ab Workout Hurting Your Back?". Well. The New York Times.
  3. ^ Baker, Cameron. "Are Sit Ups Bad for You? The U.S. Military Seems to Think So…". International Sports Sciences Association. Retrieved 17 October 2018.

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