Written by Rachel Urquhart, Allure Magazine

The image of movie stars cramming junk food on the set may not square with the seal-like physiques we see on screen, L.A. personal trainer Valerie Waters knows otherwise. “I’ve seen celebrities gain seven, even ten pounds during the shooting of a movie,” says Waters, whose clients include Richard Gere and Courtney Love. “They have to get themselves to a gym after shooting at midnight of before they’re called, at 4.a.m. It got me thinking. Wouldn’t it be great if they could fit it in while they were on set?”

So Waters started the Muscle Truck Company. A 48-foot-long mobile workout trailer equipped with everything from Cybex to surround sound, available for rent to individual stars and their trainers for $2,500 a week.

“The studios used to just throw a few weight machines into an empty trailer and that was it,” she says with audible horror. “I mean, even I wouldn’t work out in there.” The atmosphere inside the Muscle Truck is decidedly more rarefied: soft lighting, sliding one-way glass doors, and a high-powered forced air cooling system crucial for actors who don’t want to break a sweat while working out between scenes.

“You won’t get in shape without sweating,” Waters explains, “but it’s enough to keep toned for a movie.” Whatever it takes to ensure that the actual muscles behind star power gets a workout.