The Abdominal Crunch Myth

In honor of tonight's The Office series finale, I thought I'd share a bit of a tangent inspired by one of my favorite characters on television, Dwight Schrute. Today's message: Don't be an idiot. 

Only a few things get me more agitated than watching people in the fitness center perform abdominal crunches. You will NEVER get a six-pack or a flat stomach from doing crunches. Never. Period.

The reason is quite simple, but unfortunately never really talked about - there is no such thing a spot reduction. You cannot target an area and find a specific exercise to reduce the amount of fat in that area. You cannot perform crunches until you "feel the burn" and assume you are trimming down the beer belly. One source claims it takes 5,000 crunches to burn... 1 pound of fat. That poor soul who had to endure 5,000 reps! I could go on for an hour about why they are a terrible choice for a core strength exercise, but I will just highlight the main points. 

The intervertebral disc in the low back (lumbar) region is very susceptable to injury during improper mechanics of movements. Anytime you are in an upright position, heck even when you are sleeping at night, there is a given amount of pressure on these discs. In severe situations where too much pressure is placed on the disc, an injury can occur. Every time you bend over to touch your toes you increase the amount of pressure on your discs in the lumbar spine. And, any time you couple flexion with any rotation, you are begging to blow out a disc. Isn't a crunch the same movement? One text suggests that any flexion in the lumbar spine along with hip flexion puts 4 times the amount of pressure on the disc than our normal body weight when laying down. That means a 175lb individual will put 700 pounds of pressure on his lumbar disc during an abdominal crunch. That's a good enough reason for me to never do another crunch in my life. Well, unless I feel like blowing out a disc and skipping school for a week.

The above photo depicts the amount of pressure on the disc in a variety of movements or postures. Note that this source found only 225% in lumbar flexion solely, and only 275% lumbar flexion with hip flexion...Still, that's a little too much for my liking. 

Long story short, your discs are fantastic entities that (like everything if stressed too much) can deteriorate. Proper biomechanics and common sense can provide you with better results and less injuries. 

Some alternatives to crunches are planks, pikes, ab wheel rollouts, pallof presses, isometric theraband holds, any exercise on a TrX strap, and dozens more that are safer and more effective for you to achieve your goals. The biggest difference between these exercises and the abdominal crunch is that the crunch utilizes the rectus abdominis muscle only, whereas the other exercises mentioned utilize multiple muscles around the core in order to properly contract the abdominal musculature as a unit and perform proper biomechanics. 

TrX Atomic Pushup.

Sources
Neumann, Donald Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. Mosby Elsevier, 2010.
Andersson, Ortengren, and Nachemson. Intradiscal pressure, intra-abdominal pressure and myoelectric back muscle activity related to posture and loading. Journal of Clinical Orthopedic Medicine.