Even if you've been working out at the gym for a while, paying attention to a few simple rules of proper technique can not only make you slimmer, stronger and healthier, it can help prevent some seriously wicked injury. And in this case, here's how to to perform the perfect 'ball crunch':

Choose The Right Ball

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The first thing you have to do is to check if you're using the wrong sized ball. Using the wrong ball forces people into awkward positions. 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.

Don't Limit Yourself

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But even with the right sized ball, you need to make sure you're not limiting your range of motion. Most people only move up and down a few inches on the ball, which means they're not getting the most out of this move.

The Fix

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As you can see above, you can fix this by stretching backwards over the ball as much as is comfortable. This gives you more "room" to lift your core back up and perform the crunch.

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And be  sure to crunch on a ball with the same form you would use for a regular crunch by bringing the shoulders toward the ceiling. Perform this in front of a mirror to avoid curving you spine or pulling on the neck.