We asked Harley Pasternak, the fitness expert who has whipped A-list mamas like Vanessa Williams and Milla Jovovich into shape, to let us in on his favorite exercises for firming up the toughest zones as efficiently as possible. "By doing the most effective move for each body part, you'll squeeze in a great workout in 20 minutes," says Pasternak, author of The 5-Factor Diet. And by jumping from one thing to the next without stopping to rest, you'll also sneak in fat-burning aerobic exercise while shaping sexy muscles. Do the following moves two to three times a week and watch your confidence soar.
Best for Abs
Exercise: Double Crunch
Do It: Start out lying faceup, feet flat on floor with knees bent and hands behind head. Lift legs into air so thighs are perpendicular to the floor. Raise head and shoulders off the ground, and bring knees in toward chest (so butt is off the ground). Lower head to floor and return legs to perpendicular position. Repeat 20 times.
Why It Works: Because your feet never touch the floor, your abs are constantly engaged -- and unlike a standard crunch, it tones both your upper and lower abdominals.
Best for Thighs
Exercise: Ball Squats
Do It: In a standing position, place a beach ball between your thighs (you can also use a basketball or a pillow). Holding ball firmly, bend knees into squat position, as if you're going to sit in a chair (make sure your knees don't extend past toes). Hold for two counts; return to start position. Repeat 20 times.
Why It Works: This targets the front of your thighs, plus your inner thighs, which have to work to hold the ball in place.
Best for Butt
Do It: Stand with a step in front of you (or a stair or curb). Place your right foot on the step, pressing through the heel as you bring your left foot up to join the right. Step down with right foot, then left. Do 20 times; switch sides and repeat. For more of a challenge, raise the height of the step.
Why It Works: Any move in which you're stepping up and down will work your glutes, says Pasternak. The motion also raises your heart rate, so you burn more calories.
Best for Allover Toning
Exercise: Wood Chop with Dumbbell
Do It: Stand with feet shoulder-width apart, holding a weight in front of you. Bend knees as if you're sitting in a chair, so thighs are almost parallel with floor. As you bend, rotate shoulders to the left, bringing weight toward left knee. Straighten legs, twisting torso right as you raise weight diagonally over your right shoulder. Repeat 10 times; switch sides.
Why It Works: The squat incorporates your glutes and thighs, while the twisting motion targets your obliques, Pasternak explains.
Best for Lower Body
Exercise: Walking Lunge with Trunk Twist
Do It: Start with feet together, holding a ball in front of you with both hands. Step forward three to four feet with right leg, as shown, lunging forward until thigh is parallel to floor, knee over ankle. As you lunge, twist torso right, keeping head and pelvis facing forward. Bring torso back to front. Pushing off with right heel, bring left foot forward into a lunge and twist torso to left. Do 20 lunges -- 10 each side.
Why It Works: Lunges target glutes, quads, and hamstrings. The torso twist works your abs, particularly the obliques.
Originally published in the July 2009 issue of Parents magazine.