Yes, you can pump iron without bulking up. No, you won't look awkward. Learn how to get stronger and unlock a mighty metabolism, too.

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Getty Images If you've heard it once, you've heard it a million times: You've gotta strength train. Building muscle not only tones your body and boosts your metabolism but also improves your heart, bone and joint health. Yet far too many of us still shy away from the weight room. In fact, only about 20 percent of American women get in the recommended two strength sessions per week, research reveals.

What's holding us back? "Many women are intimidated," says celebrity trainer and Asics strength coach Michelle Lovitt, who has worked with Courteney Cox and Julianne Moore. "They don't want to get injured and are afraid they will look too muscular."

Instead we stick with yoga and barre classes, not realizing that they're less powerful workouts. "These classes are designed more for building muscular endurance—the ability to fire muscles repeatedly before fatiguing—as opposed to muscular strength," explains Michele Olson, PhD, an exercise physiologist at Auburn University at Montgomery in Alabama. To see true strength gains, you need moves that place added resistance (from body weight, dumbbells, bands) on your muscles.

It's time to woman up. Once you face your dumbbell fears, you can reap all the body benefits.

Worry #1: You don't know what you're doing
Unlike with the guys, weight training is not something many of us grew up with. "When I started going to the gym, I avoided the weight room like the plague," says Leah Belisle, 31, of Seattle. "I didn't know which weights to grab, how to use them or which muscle groups to work together."

It's actually wise not to just wing it. Simple things like not knowing how to adjust the seat height or positioning on machines can hamper your progress, preventing you from engaging the correct muscles and potentially leading to injury. So how do you learn the ropes? "Meet with a reputable, certified trainer a few times and have her walk you through the basics," Lovitt says. Many gyms offer a complimentary training session with new memberships.

One good beginner tip: Start by using your body weight as resistance. "Hold off until you can execute the moves properly, then begin adding weight in 5-pound increments," says Curtis Williams, director of the Under Armour Performance Center in New York City. "When the weight feels easy, it's time to increase. Keep in mind that your last two or three reps should be fairly challenging."

Worry #2: You'll bulk up
Repeat after us: Lifting weights will not turn me into Arnold Schwarzenegger. "One concern I still hear from women is that they're going to gain too much muscle," says Harley Pasternak, the trainer behind Megan Fox, Katy Perry and Rihanna. "But you need three things to add bulk: testosterone (which is why men get bigger muscles), extra calories (if you want to build a bigger house, you need extra wood and concrete) and high-volume training (meaning you target one large muscle group, working it to exhaustion with 20 to 30 sets of exercises a day)." It's a simple biological fact that women don't naturally have the testosterone necessary to build gigantic muscles. In fact, Olson notes that many female bodybuilders look hulklike partly because they take illegal hormones.

So don't use only superlight weights. "To force your muscles to rebuild and repair, which is when growth and toning occur, you need a resistance that fatigues the muscle within about 90 seconds per set," says Wayne Westcott, PhD, fitness research director and professor at Quincy College in Quincy, Mass. Pumping iron like this just twice a week can reduce your overall body fat by 3 percent in 10 weeks. Translation: You'll look leaner, not huge.

Worry #3: Everyone is staring
You picture yourself walking into the weight room: All the lights go down, a spotlight clicks on and suddenly a roomful of muscleheads are looking critically at you. "This is called social physique anxiety," says Katie A. Rickel, PhD, clinical psychologist at Structure House in Durham, N.C. "The reality, however, is that most people are focused on their own form—not on you." To ease insecurity, it helps to be prepared. "Write your workout down and go to the gym with a plan in place," Williams advises.

Still a Nervous Nelly? Limit the number of eyes on you by avoiding the gym at peak times (usually early morning, late afternoon and evenings), or fine-tune your lifting in a less busy space, like an empty fitness studio. Or just embrace the crowd. "By going to the gym at a similar time each day, you'll begin to see familiar faces and make friends," Rickel says. "This, in time, will help you feel less self-conscious."

Related: Try This Flat-Belly Yoga Pose Worry #4: You won't burn enough calories
Few things are more satisfying than hopping on a treadmill, running for a half hour and then seeing, right on the console, that you blasted off 300 calories. Sadly, there's no such read-out when you lift weights. But there is a sneaky perk to strength sessions: It takes a lot of energy (aka calories) to repair those muscles post-workout, which boosts your resting metabolism for a few days afterward.

One study found that women who did as little as 15 minutes of strength training torched about 100 calories more over the day following their workout than they did when they didn't lift. Another plus: As you get stronger, you use your muscles more effectively, which enables you to burn more calories during cardio, Olson says. The final benefit? The more might you have, the better you'll feel. "Everything we do takes a certain amount of strength," Westcott explains. "So as we increase ours, everything else in our lives—lifting the baby, putting groceries in the car—becomes easier."

Next Page: Gym machines, decoded [ pagebreak ]
Master the Machines
One of the most intimidating things about the weight room is being surrounded by crazy-looking contraptions that you've never seen, let alone used. But don't worry—here, weight-training experts Curtis Williams and Wayne Westcott, PhD, help you ace some of the most useful machines in the room.

TRX suspension trainer
This functional training tool forces you to stabilize yourself while doing body-weight exercises—think jump squats, push-ups, tricep dips, mountain climbers, single-leg squats, flyes, lunges, hamstring curls, bicep curls and oblique pikes. You can adjust your body placement to make an exercise as easy or difficult as you like.

Cable machine
This forces you to activate your core as you strengthen other parts of your body, and it's a great way to add resistance to rotational movements such as wood chops, as well as to rows, hip adductions, tricep extensions, flyes, lat pulldowns, shoulder presses and crunches.

Seated row
This cable-based, fixed-motion machine employs a rowing motion to target your upper back better than the standard lat pulldown bar. It also offers a bit of core strengthening.

Seated chest press
A counterpart to the row, it works almost all your upper body's pushing muscles.

Your Strength-Training Toolbox
The best way to train is like an athlete, "performing functional, compound movements that work multiple muscles at the same time," says Josh Newman, co-founder of CrossFit NYC: The Black Box. Grab these tools and try these moves, doing 10 reps of each 2 or 3 times a week.

Why it's key: You can perform total-body moves that work upper and lower body simultaneously.

One good use: Overhead press: Stand with feet hip-width apart, holding a dumbbell in each hand, elbows bent by sides, weights just above shoulders (A). Press arms overhead (B); return to start.

Why it's key: Its design challenges your stability.

One good use: Kettlebell swing: Stand with feet slightly wider than shoulder-width apart, gripping kettlebell handle with both hands. Squat as you swing kettlebell between legs and slightly behind you (A). Driving from hips, swing the kettlebell in an arc to shoulder level (B). Return to start.

Medicine ball
Why it's key: It's ideal for performing dynamic actions.

One good use: Wall ball: Stand facing a wall a couple of feet away, holding ball at chest level, feet slightly wider than shoulder-width apart. Squat (A); as you rise to standing, extend arms and toss ball up against wall (B). Catch ball and immediately drop back into squat position.