This torso transformer was inspired by the floor-wiper exercise from the famed "300 workout," the über-intense regimen that (more than the magic of CGI) carved Gerard Butler and his fellow Spartans into sinewy warriors. It fiercely works your chest, upper and lower back, shoulders, arms, abs, and obliques while forcing you to maintain balance. In short, it's the perfect pre-beach mid-and-upper-body sculptor. But know this: It requires intense focus on form, so start slow and go light with load at first. To maximize its fat-burning potential, cycle this muscle builder between up-tempo cardio intervals. Do 8 to 10 reps for a total of three sets, either in a row or as part of a larger circuit. Take a few minutes of rest between consecutive sets.
Step one: Lie flat on the floor, holding a set of dumbbells (or a barbell). Grip the bells so your hands are slightly wider than chest-width apart, palms facing your feet. Brace your core and press up, then slowly come straight down so the bells lightly touch your sternum. Hold for a beat, exhale, and press back up, straightening your arms. Hold. Be sure not to lift your head off the floor and that you never strain your neck.
Step two: Keeping your legs as straight as possible and your knees touching, squeeze your abs and obliques and lift your legs up so they're at a 45-degree angle to the floor. Hold for a beat. Remember, engaging your core is the secret to keeping the bells level during the leg movements.
Step three: In a controlled movement, slowly spread your legs out to the side, like you're doing a spread-eagle. Then bring your knees back together, keeping your legs straight. Next, lower your legs to the floor. That's one rep.