Most guys learn to do pushups in the fourth grade. Ever seen a fourth-grader do a pushup? It's not pretty. And unfortunately, few people ever get better.

"Unless they've had instruction before, I’ve never seen someone off the bat do a pushup perfectly,” says metabolic training expert B.J. Gaddour, C.S.C.S., creator of the follow-along DVD series Men's Health Speed Shred. "I see 99.9 percent of people do it wrong."

But performing pushups incorrectly can make your lower back ache, hurt your shoulders, and keep you from getting the most muscle-building benefits out of the exercise. Here are the top pushup mistakes -- and Gaddour’s fast fixes.

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