Hard core: these gut-busting moves will get your middle into tip-top shape

aBDOMINAL WORK ISN'T JUST about pounding out more reps. Serious ab development is about homing in deep, and controlling your body at its core. When you move during exercises that require balance, the midsection muscles must rise to the occasion and provide stability so that you can execute each motion with power and precision.

That's exactly what the classic reverse curl teaches you to do: Tilting your pelvis, rolling your hips off the floor and then lowering requires considerable command of the abdominal muscles. And the more advanced ab pike raises the abdominal-training bar higher. Adding the extra weight of your legs and increasing the range of motion make it necessary to use maximum control and strength.

Asking more of your middle can take ab workouts to a new level. It not only focuses on the uppermost rectus abdominis muscle fibers, it kicks in those hard-to-reach rectus fibers as well. The obliques and the deepest of the ab muscles, the transverse abdominis, also get a thorough workout. The result is more even muscle balance, stronger, more supportive abdominal muscles and your fittest-looking middle ever. So try this month's classic exercise as well as its update--get ready for abs that rock!

REVERSE CURL

START: Lie faceup with arms at your sides, palms down. Bend your knees and lift your feet off the floor so that your thighs are directly over your hips and your calves are parallel to the floor. Pull your abs inward.

EXERCISE: As you exhale, draw your belly button closer to your spine to contract your abs. Tilt the lower part of your pelvis upward so that your hips roll up and back until your glutes and tailbone are lifted off the floor, but your back remains in contact with it. Pause, and then, using your abs to control the movement, slowly roll back to the starting position, inhaling as you lower.

TIPS

* Keep your neck and shoulders relaxed; don't tense them up as you roll your hips upward. And don't press your hands or arms forcefully against the floor to help with the move.

* Avoid swinging your legs back and forth. Minimize momentum by pausing after each phase of the move.

* For more of a challenge, raise your head, neck and shoulders off the floor into a crunch position and keep it stationary as you perform the reverse curl.

* To keep your abs engaged throughout the entire set, avoid letting your lower back arch off the floor as you return to the starting position.

AB PIKE

START: Lie faceup with arms at your sides. Bend your knees and lift your feet off the floor so that your thighs are directly over your hips and your heels are near your glutes. Pull your abs inward.

EXERCISE: Exhale and contract your abdominals as you straighten your legs upward and lift your hips straight up off the floor. Just before your lower back pops up off the floor, pause, then lower slowly back to starting position with control, inhaling as you lower.

TIPS

* This exercise is all about control and pure abdominal strength, so strive to take all the momentum out of it. The slower and more precisely you move, the more you'll feel it in your abs.

* Focus on using your ab muscles rather than your hips or torso. Your aim is to keep your ab muscles engaged the entire time, rather than attempting to lift your hips as high as you can.

* Monitor your stability: If you feel unbalanced at the peak of the lift, don't lift quite as high on subsequent reps.

* Keep your straight legs balanced above your hips during the lifting and lowering phase.

* If your back bothers you, bend your knees slightly.

* As with the reverse curl, keep your neck, shoulders and arms relaxed. Don't tense them up as you lift.

WHAT'S THE DIFFERENCE?

The rectus abdominis, the so-called six-pack, is one long, flat muscle that spans the front of your torso from breastbone to pelvis. The obliques are the two pairs of muscles that wrap around your torso like a corset: The external obliques form a V-shape down the sides of your torso starting from the lower ribs and running diagonally down toward your pelvis; the internal obliques are deeper and the muscle fibers run in an upward V diagonally from the pelvis and attach to the lower ribs. The deepest abdominal muscle, the transverse abdominis, runs horizontally across your lower abdomen and around your back; it contracts deeply to stabilize your middle as the other muscles are working.

The ab pike is a turbocharged version of the reverse curl. Both the classic reverse curl and the updated ab pike blast all the abdominal muscles, but the ab pike calls upon them to work much harder. To begin with, straightening your legs upward when you pike creates more resistance for your abdominals. And since you also need a greater amount of stability to execute the pike, you must recruit the obliques more heavily to keep the lift steady and controlled. Your transverse abdominis engages during both moves but particularly during the pike to help maintain balance, to force-fully exhale and to stabilize the rest of your body as your hips move. As a result, during the pike you wind up working more and deeper muscle fibers.