Linda Pellegrino thought she was in great shape, but the cardio kick-boxing classes she's taken for the past year have made her think twice. "Roundhouse kicks make me feel like a Weeble. I wobble all over the place," says Pellegrino, a project manager at Merrill Lynch.

Many exercise enthusiasts are feeling a tad tipsy these days, thanks to the fact that popular fitness formats like yoga, tai chi, kick boxing and other martial arts tax balance to the max.

"Until recently, balance has been underemphasized, if not ignored," says Suzanne Nottingham, a California-based fitness trainer and American Council on Exercise spokeswoman. "But these newly popular classes have brought balance to the forefront."

And it's about time that balance made its way onto the fitness radar, since it is as important as core strength (abs, lower back and butt) for stabilizing the body and preventing injuries.

Even if you're a couch potato, balance deserves attention, according to Paul Frediani, a trainer at Equinox Fitness Club on W. 76th St., and author whose newest book, "Surf Flex Workout" (Hatherleigh Press), comes out in June.

"Even when you simply stand around by the coffee machine at work, you're going to lean more on the right if you're right-handed," Frediani says. "If you take the time to tune in to balance, you will find out how unbalanced your body is and how much you can improve it."

Balance is an intricate system that relies on information from the eyes, inner ear, muscles, joints and our sense of touch. "The more quickly the body reacts to imbalancing forces, the more quickly balance is recovered," says Nottingham.

As such, sports enthusiasts can reap benefits from balance conditioning and not just folks recovering from injury or surgery, or the elderly, who are prone to falls. "Balance training boosts body awareness, which tells you where you are in space," says Frediani.

Consider: An ongoing study at the University of Pittsburgh Medical Center for Sports Medicine revealed that balance shortcomings in female athletes contributed to the fact that women tear their anterior cruciate ligament two to eight times more often than their male counterparts.

"If you train the body to be more reactive to imbalance, this awareness facilitates the precision of movement and helps prevent injuries," says Scott M. Lephart, Ph.D., director of UPMC's Neuromuscular Research Laboratory.

The ideal balance program is one that challenges you when you're standing still (static balance) and in motion (dynamic balance).

"You want to stimulate your nervous system beyond your habitual movement patterns and range of motion," says Nottingham. "Plain old lunges are awesome for balance conditioning." Basketball, jumping rope and Hacky Sack do the trick, too.

Ditto surfing, whether you're on the water or dry land. In his new fitness class at Equinox, Frediani puts students on Swiss balls (used for years for rehab and physical-therapy offices), which simulate an unstable, watery environment. Result? Participants find their balance and coordination being put to the test.

"When you train the body for balance, you also train the brain and the nervous system," he says. "It's an integrated process." Not to mention one with recognizable results. "I've worked with people who found sitting on a Swiss ball difficult," he says. "Today, some of those same people can perch on top of the ball like a gymnast." If not a surfer dude.

BALANCE BOOSTERS

If you can't do these drills without wobbling, that's the point. "As you do these exercises," says Nottingham, "losing your balance is necessary to advancing."

* Stand on one foot. Raise the other foot off the ground. Hold the position for one minute. "It's a long time," says Nottingham. Repeat, lifting the other foot.

* If the above exercise isn't a challenge, close your eyes and try it. Or try doing it on a squishy gym-mat surface.

* If you like to use a stair-climbing machine at the gym or at home, see how long you can go before you need to hold on.

* Sit on a Swiss ball and lift one foot off the floor a couple of inches is okay, but if you can, extend your leg so it's parallel to the floor. Hold the ball and yourself steady in that position for a minute. Repeat with the other foot.

* Starting in a kneeling position, place your hands shoulder- width apart on the floor and then place your feet on the ball. Hold that plank position for 30 seconds. If that's easy, try doing pushups. Shoot for 10.