Core Work...

Reverse crunch: Lie on back, legs raised with knees bent 90 degrees. Squeeze a sports ball (or folded towel) between knees and rest arms at sides. Contract abs to curl hips off floor (as shown). Slowly lower hips for one rep.

Ball crunch - Sit on a stability ball, feet flat and hands clasped behind head, elbows out. Lower upper body until back is resting on ball. Slowly crunch up as you lift right leg as high as you can while maintaining balance (as shown). Lower to start; repeat with left leg for one rep.

Stand-up slimmer - Stand with feet hip-width apart, a 3- to 10-pound dumbbell in each hand. Raise arms out to sides at shoulder level, elbows bent 90 degrees (like a goalpost), palms forward. Lean torso to left as far as you can (as shown). Return to upright; repeat on right side for one rep.

Treadmill vs. Hitting the Road

In terms of building bone strength, they work equally well.

Q: Is walking on a treadmill just as good for increasing bone density as pounding the pavement?

A: Yes. Whether you're doing laps around the neighborhood or trekking on a treadmill, the crucial element is the same: weight-bearing activity.

"To build bone, you need to move your muscles and bones against the force of gravity," says Wayne L. Westcott, PhD, fitness research director. Eventually your bones adapt to the weight and the pull of muscles by producing more cells and becoming stronger. Although you'll reap bone-building rewards regardless, the harder the surface you walk on, the faster you'll get results. When the ground doesn't give beneath your feet, there's more impact and, therefore, more pressure on the muscles and bones, Westcott notes. You may want to opt for a concrete path instead of a dirt track, or a treadmill with a belt that's board-supported over one that gives. Remember, though, hard surfaces are best for walking, not running. Jogging on a rigid surface puts too much stress on joints and may cause injury. Regardless of your pace or the inflexibility of the surface, always lace up in quality, shock-absorbent shoes with thick midsole support.

Burn Belly Fat Faster

A spare tire doesn't just make it harder to button your waistband--it can hurt your heart and boost risk of diabetes and cancer. But you can flatten it fast by speeding up your workouts.

In an 8-month Duke University study of 175 overweight 40- to 65-year-olds, two groups exercised and a third stayed sedentary. The couch potatoes' deep, organ-smothering abdominal fat spiked 8.6%. A group that did low-intensity workouts (such as walking at an easy pace) for 30 minutes a day, 5 days a week, kept their girth from growing--though they did gain 1 1/2 pounds. The real rewards came with higher-intensity workouts: In the same amount of time, the third group shrank their waistlines and belly fat by 7%--and they lost 6 pounds.

"All exercise helps prevent fat gain," says researcher William Kraus, MD. "But to lose abdominal fat, you have to work harder."

How hard? In the study, successful losers aimed for an effort of 6 to 8 on a scale of 1 to 10. That's what you muster for brisk walking uphill, jogging on flat terrain, or pedaling a bike about 12 MPH. Beginners should start with 10 to 15 minutes and slowly work their way up.