Six Moves to a Six-Pack

Nothing says "fit" like a wash-board stomach. And nothing makes achieving one harder than doing the same exercises every week. "Your body adapts and stops responding to exercises over time, stalling your progress," says Bill Hartman, C.S.C.S., co-owner of Indianapolis Fitness and Sports Training. That's why it's important to regularly hit the refresh button on your ab routine. "Adding different exercises to your workouts gives your muscles a new stimulus and triggers growth," says Hartman. The result: head-turning abs in significantly less time.

But attracting more attention at the beach—and in the bedroom—isn't the only reason to pursue a chiseled midsection. "A strong core helps you maintain the optimal alignment of your pelvis and torso in everything you do, whether you're going big at the gym or carrying a cooler across a campsite," says Hartman. "If you can't maintain that alignment—characterized by a natural S-curve in your spine—your joints are thrown out of whack, increasing your risk of injury and limiting the amount of weight you can lift."

This summer, take a break from your usual ab exercises and weave two of these moves into each of your weekly workouts. Which two you pick doesn't matter as long as you choose a different pair each time. Then prepare yourself for the result: a six-pack that goes everywhere you do.

KETTLEBELL PULLOVER

HOW TO DO IT: Lie on your back and raise your legs. Bend your knees 90 degrees and spread them apart while keeping the bottoms of your feet together. Lift a kettlebell straight above your head, holding the sides of the handle in both hands. Lower the weight behind you, stopping a foot off the floor. Hold for 30 seconds, and lift it back above your head. That's 1 rep. Do 5.

WHY IT WORKS: "Pulling things overhead while lying on your back is what you did when you were a baby," says Hartman. "It's a natural movement that perfectly aligns your extremities and loads your trunk, activating and strengthening your core."

Want more kettlebell moves? See if you can swing it with this classic kettlebell swing challenge.

PLANK CABLE ROW

HOW TO DO IT: Attach a handle to the low pulley of a cable station and face it in a plank position, resting your weight on your forearms. Grab the handle in your right hand with your arm outstretched. This is the starting position. Pull the handle toward your right side, stopping when your elbow touches your ribs. Return to the starting position. Do 3 sets of 10 reps per arm.

WHY IT WORKS: "Pulling weight toward you in a plank engages your lats, abs, and obliques," says Tony Gentilcore, C.S.C.S., a trainer at Cressey Performance in Massachusetts. "That not only rocks your core and boosts torso stability but also helps you build a better-looking back."

KETTLEBELL RACK CARRY

HOW TO DO IT: Grab two kettlebells and "rack" them, holding the kettlebells in front of your chest with your elbows tucked, your palms facing in, and the bottom of each bell resting between your biceps and forearms. Walk 50 to 75 feet. That's 1 set. Do 3 to 4, resting 30 to 45 seconds between them.

WHY IT WORKS: "When you walk with weight in the racked position, your core has to work extra hard to keep you steady," says Zach Even-Esh, founder of Underground Strength Gym in Edison, New Jersey. "That forced stabilization is one of the most effective methods there is for developing strong abs and a healthy back."