6 moves to a 6-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," said Bill Hartman, 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," Hartman said. 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," Hartman said. "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 the moves on the following page 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.

Challenging your body in new ways hits your muscles at different angles, packing on size. For all-new exercises from Men’s Health experts, subscribe to our Exercise of the Week newsletter.

1. 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 one rep. Do five.

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

2. 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 three sets of 10 reps per arm.

Why it works: "Pulling weight toward you in a plank engages your lats, abs, and obliques," said Tony Gentilcore, 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."

Protect your back my mastering your form on this exercise. Click here to see trainer David Jack teach you The Best Way to Do a Barbell Row.

3. 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 one set. Do three to four, 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," said 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."

(Consistent workouts mean better results. Learn the 13 Fitness Rules Winners Follow and you’ll never blow off the gym again.)

4. Half-Kneeling Vertical Pallof Press

How to do it: Attach a triceps rope to a cable machine and turn away from it while holding the ends of the rope in your hands on either side of your head. Drop into the bottom position of a lunge, with your front knee bent 90 degrees and your rear knee touching the floor. Brace your core and press the ends of the rope overhead until your arms are fully extended. Pause, and lower them. Do three sets of eight reps.

Why it works: "This move forces your abs to battle against the backward pull of the weight stack," Gentilcore said. "That's a new stimulus for most guys, making it a good core builder that also smokes your shoulders."

Want to add pounds to your press? Find out how to Boost Your Bench.

5. Band-Resisted Jackknife

How to do it: Secure a looped resistance band to a pullup bar and suspend your ankles in the end as you assume a pushup position. Without rounding your back, bend your knees and pull them toward your torso. Pause, and return to the starting position. Do three sets of eight reps.

Why it works: "This exercise forces you to move your hips and thighs against resistance while keeping your core stable," said Mike Robertson, co-owner of Indianapolis Fitness and Sports Training. "It's a jackknife on steroids, and it builds the type of core strength you need to maintain stability during big lower-body exercises, like squats and deadlifts."

6. Diagonal Wheel Rollouts

How to do it: Kneel and grasp the handles of an ab wheel, holding them directly beneath your shoulders. Without moving your knees, brace your core and roll the wheel forward and to the right as far as you can without letting your hips sag. Pause, and return to the starting position. Do three sets of 10 reps per side.

Why it works: The rollout starts with the stretching of your abs and obliques and ends with their forceful contraction. "That leads to a good muscle-damage response," said Craig Ballantyne,creator of Turbulence Training. "Your body then repairs the damage by packing on muscle, making you stronger."