Abdominal_crunch
Crunch (exercise)
Abdominal exercise
The crunch is an abdominal exercise that works the rectus abdominis muscle.[1] It enables both building "six-pack" abs and tightening the belly. Crunches use the exerciser's own body weight to tone muscle and are recommended by some experts[like whom?], despite negative research results[citation needed], as a low-cost exercise that can be performed at home.[2] Crunches are less effective than other exercises such as planks and carry risk of back injury.[3]