Why crunch when you can plank? Ab exercise works your core

Plank your way to a firm waist.

Although abdominal crunches and sit-ups may be the most popular "ab" exercises, they only work a fraction of what's referred to as the core.

Those are the muscles that lie deep within your abdominals, hips and back that attach to the spine and pelvis, such as the rectus abdominis, transverse abdominis, internal and external obliques, erector spinae, and rectus femoris.

These muscles work together to keep proper posture and midsection muscle tone.

The plank exercise adds a greater sense of stability and functionality than the crunch or sit-up and therefore is a better all-around core exercise.

How to perform a plank:A plank position is basically a push-up position on your forearms. Elbows should be directly under your shoulders and bent at 90 degrees. You are looking to maintain a straight line from your ears, through your shoulders and hips and to your ankles. Maintain a slight natural curve in the low back and keep the knees slightly bent. Squeeze your abdominals and continue to breathe as you hold the position. Begin by doing three sets until you can't maintain the stance any more. Eventually, you will be able to hold a plank for more than a minute at a time.Mistakes to avoid:Don't drop your hips too low or push your butt up in the air. Keeping your spine in alignment makes planks more effective.Don't shift your body forward as you get fatigued.Don't hold your breath. Your muscles need oxygen.Increase the intensity:Try performing the plank on a stability ball. The added challenge will elicit more muscle contractions and make those muscles work harder.You can even try reaching your arms forward slowly to recruit even more muscles. Be sure to keep your entire body rigid and reach only with the arms.So give the plank a try and you will soon notice better posture and a tighter mid-section.bull; Joshua Steckler and Mark Trapp are co-owners of Push Fitness, a personal training studio in Schaumburg specializing in weight loss, muscle toning and nutrition. Contact them at PushFitnessTraining.com.False20001140Push fitness owner Joshua Steckler demonstrates the correct way to plank using a stability ball. The challenge makes the core muscles work harder.Mark Black | Staff PhotographerFalse