It doesn't matter how much you can lift or how long you've been lifting--one bad move can still land you on the disabled list. "Some of the most popular exercises out there are also among the most dangerous and ineffective," says Mike Boyle, owner of Mike Boyle Strength and conditioning in Woburn, Mass. Purge these body breakers from your routine before they stall your progress--or send you to the sidelines.

(Find out who topped the list of the 100 Fittest Men of All Time as selected by the editors of Men's Health.)