Why it's bad: You might think it's low impact, but it's putting your body in wacky positions. "The elliptical takes your body through an unnatural range of motion, unlike anything your body would do in real life," he says. "Besides, any piece of equipment that encourages you to read a magazine while exercising shouldn't be in a gym."
What to do instead: Channel your inner Winklevoss and hit up the rowing machine. "If you're going to be on a piece of cardio equipment, this is where you should be," McCarthy says. "The rowing machine not only works almost every muscle in your body, but it also teaches you proper pulling mechanics. Revving the intensity up on this is a killer—try doing ten rounds of 30 seconds as hard as you can, and then 30 seconds of light rowing."
LEG PRESS
Why it's bad: Unless you're rehabbing an injury, steer clear of isolation exercises. "The leg press is an isolation exercise than places unnecessary strain on the lower back and doesn't allow for proper muscle recruitment in the legs," McCarthy says. "This can lead to all sorts of injuries of the knee and back."
What to do instead: Squats. Yes, more squats. "Once again, we find ourselves back at the squat rack," McCarthy says, laughing. "Load that barbell with a weight you can comfortably handle for three sets of five reps. Next time you squat, add five pounds to that weight, and do your 3x5 again. Continue this progression, squatting three times a week, and you'll find yourself getting extremely strong extremely quick."