NO DOUBT many a weightlifter has walked into a classic gym—say, Gold's in Venice Beach—and thought, Man, if these weights could talk. Now some can. Last week Gymbox, a fitness club in London's financial district, replaced some metal plates with human weights: people of various masses waiting to be lifted by exercisers. The liftees, who wear black leotards marked with their weights, range from a 66-pound female dwarf to a 342-pound man. "A lot of our members felt that lifting metal weights was boring and not especially motivating," says Gymbox owner Richard Hilton, who has his human plates shout encouragement to flesh-pumping customers. Finally, resistance training that isn't so resistant.