The Cutout Dress Workout

Fashion's finest sent designs down the runway that showed some serious skin. But forget cleavage. This slightly more subversive sexiness—for example, the hip-bone-and-waist-revealing Stella McCartney dress seen here—calls for amped-up versions of your usual muscle-boosting moves.

GET IN THE FAT-BURNING ZONE

The secret to looking toned all over: strategic cardio. "For many women, it's just about reducing body fat so that the muscles they already have become more visible," says celebrity trainer Gunnar Peterson.

Rather than pedaling away mindlessly on the elliptical simply for the sake of working up a sweat, add bursts of high-intensity fat-torching intervals. For instance, says Peterson, during your cardio of choice (be it treadmill, rower, or bike), first find your steady-state pace. Next, add a few all-out pushes—sprint or row as fast as you can or come out of the saddle—for 20 seconds, then go back to the starting speed for one minute, and repeat.

Need to squeeze in a fast fat-blasting workout? Alternate 15-second intervals of jumping rope quickly with jumping at regular speed for two and a half minutes total, says Natalie Uhling, founder of the NUFit studio in New York. Alternate with three minutes of toning exercises and repeat.

WORK EVERY ANGLE

From a rib-cage-baring top to thigh-high slits, to reveal a super-fit physique head to toe you need to practice multidirectional movements. Because unlike constantly working in one plane of motion, such as straight-up lunges, crunches, or push-ups, changing direction increases difficulty and works major muscles and smaller strands equally so that no specific muscle becomes overdeveloped, says Stephen Pasterino, a ModelFit trainer in New York—the workout of choice for Victoria's Secret models like Karlie Kloss. For Angel-worthy legs, do three-way lunges, going forward, back, and sideways.

For a svelte stomach that's totally toned from front to side, ditch standard crunches, says Uhling. Instead, plank with your feet on gliders (or hand towels) and alternate sliding each knee up toward the opposite elbow and back, to "work cross-body to hit the obliques as well as to fire up the hard-to-reach upper abs," she says.

To create defined, not bulky, shoulders (which accentuate the natural waist and make you look more hourglass, says Peterson), power through variations of the push-up—moving from a few with legs straight, then bent; then with your arms shoulder-width or wider apart, even feet against the wall or balancing on a Bosu ball—to hit every part of your arms, chest, shoulders, and back, says L.A. exercise physiologist Michelle Lovitt.

SLOW DOWN YOUR SWEAT SESSION

To get Doutzen-esque definition in your inner and outer thighs, try Pasterino's favorite gam-firming move: super-slow, controlled, standing leg raises (gradually lift each leg to the side, then hold, lower, and repeat).

"Lift your leg high while keeping your balance—and add a two-pound ankle weight, progressing to three, and then five pounds—and try changing the position of your foot with each lift to hit every muscle on the side of the hip," says Pasterino. "The thigh is often thought of as just one large muscle, but it's not. Slowing down the speed works each individual tiny muscle too."

The same is true for the core and arms: Take. Your. Time. Holding Pilates-style mat crunches (where you lie on your back with upper torso and legs raised, forming a C curve with your lower spine while keeping arms extended straight alongside your body) targets not only the front of your stomach but down your sides as well, says Lovitt.

"It takes momentum out of the equation because your shoulders and all of the muscles in your core are engaged the entire time," she explains. "You're essentially using only your body weight, but you're constantly fighting the resistance—it fires up your muscles big-time." And fired-up muscles = you, smoking hot, in a cutout dress.