"Your overall strength stems from your core," says Keoni Hudoba, creator of the Cyc Method, an indoor-cycling class in New York City. "It's the main pillar of your body. Your arm and leg movements originate from that center, so the stronger your core is, the more efficient you'll be in the weight room, on a run, or in cycling class." So giving your waistline a little extra attention can actually help speed your total-body results.
This routine, created by Hudoba, is a two-for-one deal: It will build that critical core strength—and score you enviable abs. Do the following moves up to three days a week, moving from one to the next with as little rest as possible after each. (You can rest for up to 60 seconds between circuits.) Repeat for a total of three circuits.
Quick Tip: Choose a medicine-ball weight that challenges your core during the last few reps without compromising proper form.
Lie on your back, feet raised and knees bent 90 degrees and arms at your sides a few inches off the floor, palms facing up (a). Brace your core and reach your fingertips toward your heels as you raise your shoulders off the floor, keeping your head neutral (b). Pause, then return to start. That's one rep. Do 10.
Lie faceup, knees bent, feet flat on the floor; extend your left leg, keeping it parallel to your right thigh (a). Brace your core and, on three counts, raise your back off the floor, keeping your head neutral and reaching your arms toward your left foot (b). Pause, then slowly roll down. That's one rep. Do five, then switch sides.