Lat pull-down behind the head: This exercise is done sitting on a machine with a weighted, cabled bar overhead. You reach for the bar, then pull it down behind your head and neck. "So many things can go wrong" with this exercise, says Warpeha. Alignment is number one: Only people with very mobile shoulder joints can keep their spines straight enough to do this exercise properly. "Most people's shoulders aren't that flexible," Warpeha says. So the move can lead to shoulder impingement or worse, a tear in the rotator cuff, he says. Not only that, but "the tendency is to hit the back of the neck with the bar," which could injure the cervical vertebrae, adds fitness trainer and instructor Jodai Saremi, DPM. A safer alternative: On the pull-down machine, lean back a few degrees, use a narrower grip, and bring the bar down in front of your body to the breastbone, pulling shoulder blades down and together. Contract your abdominals to stabilize the body, and avoid using momentum to swing the bar up and down.