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For years, the weight room at my gym was foreign, and quite frankly, scary, territory. I didn’t touch a set of dumbbells heavier than 5 lbs. for the fear that regular sets of bicep curls with anything more would cause me to “bulk up” instead of tone and define my muscles—the personal fitness goal I set for myself.

That fear dictated how I approached working out. Raised on cardio-centric sports like swimming, I opted for the treadmill, the road, and cycling instead of exercises that focused on strength, and my goals of toner arms and abs continuously went unfulfilled.

By no means is this fear exclusive to me—it’s one I’ve discussed with many of my female friends for years, and I’d be lying if I said workout instructors hadn’t heightened it while pushing their methods of tiny pulses and movements for toning the entire bod. It wasn’t until I started regularly attending full-body cardio-based workout classes that utilized not only using your body weight, but heavy weights in the process, did I change my mind about weight training, realizing the whole “bulking up” thing is a giant misconception fed to women. Because, well, weight training and lifting completely transformed my body and upped my fitness level—I'm a stronger person than I was before.

"Truly 'bulking up' is a bit harder to do for women due to the fact that we do not have the testosterone that men do, but is absolutely possible for women to build mass,” explains my fitness instructor Carolann Valentino. In short, lifting weights alone doesn’t cause you to bulk up—it’s about how you do it.

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"'Bulking up,’ however, requires more caloric intake and heavy weight training," says Valentino. "A typical cardio workout for most utilizes lighter weights with a range of 8-20 reps. For the purpose of bulking up, less reps (8 or under) and lifting heavy weight are a few steps to building mass. Bulking up can happen quickly if you trigger the muscle fibers that withstand the most power. To simplify your question, one must truly lift much heavier weights and stick to short reps within a well planned routine."

I’d work these 45-minute classes, led by a pro, into my routine about three times a week. After a year of sticking to this routine for a year, my arms are significantly more toned around the biceps, triceps, and shoulders, but I initially started to see results within the first three to four months. This is because, as explained by Valentino, I was concentrating on short intervals of cardio power moves mixed with heavy weight training. "The cardio-strength increases the strength and endurance of your muscles, which improves cardiovascular efficiency and helps burn more calories and fat in the process. This process allows one to see more definition."

It took time to get comfortable in the weight room. My first class, I reached for 5 lb. weights out of habit. After a few weeks, my friend pointed out that lifting them required next to no effort from me. And according to Kirsty Godso, Nike Master Trainer and star of Panacea’s 21-Day Campaign, that's usually when it's time to increase. "If you're following a program you'll notice that you can incrementally up your weights even if it is by a very small amount every couple of sessions. You'll feel it in your body!," she says. "When it starts to feel a bit easy while you're still maintaining good form you know you can increase your weights a bit. Earn the progression and put your ego to the side a bit—you don't have to change your weights every session. Ideally you're trying to build up over time! A lot of programs will be with you for 4-6 weeks so the increase in weights is the fun part where you can really see your progression!"

But it wasn't just my arms that benefited from these classes with weights—my abs transformed, too. "The core works as a stabilizer when lifting," says Valentino. "The more core strength one has, the more 'work' one can output." I was also focusing on multifunctional movements that trained more than one muscle group at a time—Valentino lists reverse lunge into a squat with an over head press as an example.

Godso agrees that she's even seen success in her own abdominal fitness journey with weights. "My favorite exercises to work my core are front squats and pull ups with weights attached," she says. "My abs are always at their best when these exercises are in my program. Weight training is your ticket to building definition in your muscles."

If arms is your main goal, Valentino suggests starting with weights that create enough resistance, or to the point of muscle fatigue. "I would utilize different size weights depending on the muscle group you are working on, for example the bicep curls can usually handle more weight than raises. Be sure to target all major muscle groups–debts, bicep, triceps—and stabilizing muscles as well-higher reps and sets and repeat the routine 2-3 days a week."

Also, be sure to find a reputable program or instructor to guide you through the process in good form and free of injuries, suggests Godso. "Give yourself the opportunity to start out right and you'll continue to develop your technique and strength with everything behind you!

Finally, give yourself a realistic time frame to get to your goal. "You're not going to turn into Arnold Schwarzenegger by weight training a few times a week! Set your intentions in the right places."