Do Your Core a Favor and Ditch the Crunches

Crunches are a waste of time, period. But for some reason, this message just isn't resonating with the masses, no matter how many fitness professionals preach it. But it's true: crunches won't flatten or build your abs.

"Every smart trainer knows that if you can do a resistance exercise 50 times in a row, like you can with crunches, that there is little benefit to body composition," trainer Craig Ballantyne writes in Men's Health Belly Off blog. "Sit ups are a more difficult exercise, but like crunches, sit-ups are hard on the low back … So both are unnecessary and risky moves."

Trainer Scott Abel also argues training your abs by performing exercises that bring your pelvis to your rib cage is ineffective. "One key to understanding how the core works is to resist thinking of muscle actions in terms of straight lines. Most movement patterns are diagonal or rotational. That's why muscles, joints, and bones are connected in diagonal and spiral patterns," he writes in Death to Crunching on T-Nation.

So how do you train your abs?

Try performing static exercises that force you to control your limbs in space in a variety of movement planes and ranges of motion. A plank hold while raising one leg and holding it out to the side is a good example.

Abel also suggests movement-based exercises that force muscles to work together in multiple planes of motion and with various degrees of rotation. These include wood chop-type exercises using a medicine ball.

If you want to really challenge yourself, try lateral duck-unders. "This is generally considered a 'mobility' exercise, but I like it as a core exercise," Abel notes.

To perform a lateral duck-under, set the bar on a Smith machine to about hip-height. Stand parallel to the bar, and take a long lateral lunge as you duck under the bar, keeping a neutral spine. Bring your trailing leg through and stand up on the other side of the bar. Now lunge with the other leg and duck back under, standing up in your original position. That's one rep. Keep moving until you've finished all your reps.

Why does this matter to you? Because you shouldn't waste your time at the gym performing exercises with no benefits. Crunches don't strengthen the integrity of your spine and its connective tissues. Choose exercises that work muscles in multiple planes of motion and with different degrees of rotation, including wood chops, plank variations, medicine ball slams and lateral duck-unders.