Josh Holland's biggest challenge as a celebrity trainer is keeping workouts fun for a stable of demanding Hollywood clients and creating regimens tough enough to maintain the hardest female body in show business: Madonna's. And clearly he's succeeded, given that he's helped the Material Girl roll out classes for her recently launched chain of fitness clubs, Hard Candy (motto: "Harder is better"), which is named after her latest album. The flagship landed last year in Mexico City, decorated with Warhol-esque prints of Madonna, soundtracked by Madge herself, and equipped with cutting-edge fitness equipment and classes. One of which is a session created by Holland that focuses on his (and Madonna's) current obsession: a heavy jump rope. "It's important to challenge your body with new exercises, and adding a jump rope into the mix is a great way to do this," says the 27-year-old former college basketball player. "Plus, it's portable." In the club Holland uses the rope, along with intervals, to create a grueling 30-minute, full-body class; for Details readers he's streamlined that routine and adapted it into a 10-minute, fat-burning, muscle-building workout. "I promise that this session will get anyone sweating in minutes," he says.

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