Hollywood's Best Bodies

BURN, BABY, BURN
Alba does 30 minutes of cardio five days a week, rotating between the stationary bike and the treadmill. She varies the intensity, doing sprints or increasing the resistance on the bike (to simulate an uphill ride), so she burns even more calories during each workout.

SPEED IS KEY
The actress keeps her rear in gear with 40-minute sprint workouts-great for the legs and butt-two to three times a week. Biel alternates ten seconds of racing up stairs or around a track with 60 seconds of a slow jog.

MIX THINGS UP
The secret behind Berry's hourglass shape is variety. She does just one lower-body exercise and one upper-body exercise a day-changing the type of exercise, number of sets and reps throughout the week. The reason: Even a difficult exercise routine becomes easier with repetition and eventually loses its efficacy.

-Polly Blitzer

STEP IT UP
To work her quad (front of thigh) and glute (derrière) muscles, Diaz incorporates this move into her workout routine: Step-ups on a low bench, with 5- or 8-pound weights. Step up with your right foot, then bring our left knee to your chest. Step down, finishing with a reverse lunge. Do 10 times; repeat on the left leg.

EMBRACE NATURE
Exercising outdoors improves your body and your mind. Witherspoon's favorite activity: hiking. (Walking up a steep incline really burns fat.)

Johansson is living proof that you don’t need to spend all day in the gym to look healthy. During the filming of Match Point, her workouts were straightforward-45 minutes three times a week of simple moves like lunges, push-ups, chin-ups and squats. She did these moves as a circuit-one after the other with no rest in between-to keep her heart rate up, thus combining both strength training and cardio.

Since giving birth to her son Johan, the supermodel is taking a more laid-back approach to getting in shape. Instead of vigorous workouts like she did after having son Henry, Klum's now doing yoga several times a week. Two other ways busy new moms can incorporate exercise into their day (and bond with baby): Bounce on a stability ball while holding your infant, or snuggle them in a sling and walk up and down stairs.

The 44-year-old keeps her body rock solid by biking, running, and, when she’s at her home in Idaho, snow shoeing and cross country skiing. The body is more challenged, as it never gets used to doing only one sport. Changing things up also prevents the wear and tear that comes from repeating a single activity, especially as you get older.

Crow says good-bye to flabby underarms by doing tricep extensions to stretch and strengthen her muscles. Stand and hold a dumbbell with both hands, elbows bent behind your head to 90 degrees. Straighten your arms, squeezing the triceps. Repeat until fatigued.

Three basic moves-squats, push-ups, and sit-ups-work every muscle in your body. Hudson does a circuit of 25 each, repeating four times (with a minute of rest in between).

If someone else is depending on you to work out, you’ll be more likely to fit it into your day (can you say "guilt trip"?). Take a cue from Reese Witherspoon and find a fitness partner with similar goals to help you get moving. If you can't find a friend, try locating a partner near you at readytosweat.com or post a listing on your gym’s bulletin board.

"Charity runs are a rewarding way to get in shape," says celebrity trainer James Bowman of New York's Peak Performance. "Because they raise money for a good cause, they double the feel-good benefits of the workout." To find the next event in your city contact a local running club or check in with Susan G. Komen for the Cure to find races around the country.

At left: Halle Berry at a

Revlon Run/Walk for Women.

Want to bust exercise boredom? Some celebrity trainers now offer a variety of audio-guided workouts, set to high-energy tunes, designed to increase your speed and elevate your mood. Log on to GYMp3 for workouts from Kathy Kaehler, who’s trained everyone from Claudia Schiffer to Michelle Pfeiffer (at left); get customized workouts from dozens of other top trainers at podfitness.com.

A great post-workout snack: Dark chocolate and raw almonds, both proven antioxidants. “The darker the chocolate, the better for you,” says Joe Dowdell, who trains Claire Danes (at left) at New York's Peak Performance. Bonus: A new study has found that the flavonoids (antioxidant compounds) in dark chocolate may help lower your chances of developing heart disease.

Hollywood's best bodies look great in jeans. Cameron Diaz scores this relaxed-chic look by pairing comfortably faded 7 for All Mankind straight-leg jeans with a flowing top and heels.

BUY JEANS LIKE CAMERON'S 7 for All Mankind, $198; at 7forallmankind.com

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