A gym is a great place to see the adage "a little knowledge can be a dangerous thing" brought to life. Every day, I see well-educated, competent adults injuring themselves in pursuit of fitness. And while their exercise mistakes may cause them pain and even serious injury, they're not the only ones feeling discomfort. You have no idea how unpleasant it is to watch someone blithely wrecking her cervical spine while the thought-bubble over her head reads, "I'm flattening my abs!"

The following are some mistakes that will send me flying across the room to intervene. Unfortunately, I can't be everywhere so I'll share a few of the more common mistakes I've seen:

Just Say No to Neck Crunches!

When performing a crunch (or curl, as we now call them), do not yank or your head. Do not pull firmly on your head. Do not initiate motion with your head. In short, leave the chiropractic adjustments to the licensed professionals. Violently yanking your head forward is not only lousy for your cervical spine (the upper portion of your spine); it also makes for a crappy ab exercise.

If you're a chronic head-puller, here's my fix: Clasp the palms of your hands together, interlacing the fingers. Place your clasped hands under your chin and against your throat. Perform your curl with the hands never leaving this position. Aha! Harder, isn't it? Now that you're not yanking on your head, your abs have to do the work. I can hear you asking, "But now that my head isn't supported, won't my neck be straining?" The answer is, "Not really." While your neck will indeed be supporting your head, it ought to have no problems doing so. And even though you are asking your neck to contribute, you're being far kinder than when you snap it forward by "supporting it" a bit too enthusiastically.