07/31/2012 08:08 am ET

Fix Your Form: How To Do The Perfect Crunch On A Ball

If you don't know your way around a weight room, heading to the gym can be intimidating -- and even dangerous. But paying attention to a few simple rules of proper technique can make you slimmer, stronger and healthier all over.

That's why we asked John Romaniello, trainer, author and founder of Roman Fitness Systems to show us what's what when it comes to strength training.

He'll be helping us tackle some of the most common mistakes we all make while building muscle, plus giving us tips and tricks for better form. This week, we're perfecting crunches performed on an exercise ball.

The Faux Pas: First things first: You're probably using the wrong sized ball, Romaniello says. "It forces people into awkward positions." This can be a little tricky, because not every gym has every size fitness ball available. Look for one that allows you to plant your feet on the ground with your knees as close to a 90-degree angle as possible.

Even with the right sized ball, it's possible you may not be getting the most out of this move if you're limiting your range of motion. Romaniello says he sees many people only move up and down a few inches on the ball.

The Fix: Stretching backwards over the ball as much as is comfortable gives you more "room" to lift your core back up and perform the crunch.

Be sure to crunch on a ball with the same form you would use for a regular crunch. Avoid curving the spine or pulling on the neck by bringing the shoulders toward the ceiling.

Tell us how it goes in the comments below, and be sure to check back over the following weeks to fix your bench press, bicycle crunches and more.

Check out more in our Fix Your Form series below:

Fix Your Form

Photos by Damon Dahlen, AOL

For more on fitness and exercise, click here.

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