"I'll bulk up."
You won't, in large part because women have only a fraction of the "male" hormone testosterone, which helps promote muscle tissue growth. As a result, women build less muscle mass than men, and they do so at a slower pace. Keep in mind, too, that a pound of muscle takes up about 18 percent less space than a pound of fat, so as you burn fat and replace it with muscle tissue, you'll actually look smaller.
"I thought I was supposed to focus on cardio."
Cardio, as its name suggests, is excellent exercise for your heart. But when it comes to burning fat, strength training can be more effective. I recommend adding a 30-minute session to your workout routine twice a week.
"I'll hurt myself."
You can reduce your risk of injury with these steps:
Warm up. Muscles require nutrients to function optimally, and those nutrients are delivered via blood. Before you work out, improve blood flow throughout your body with a light jog or uphill walk. You'll also raise your core temperature, and muscles respond better when they're warm.
Breathe. Exhale while you contract your muscles (especially if you have hypertension); inhale as you relax. This pattern helps keep your blood pressure in check.
Get guidance. Hire a personal trainer for at least one session; an hour should be enough to learn the basics of proper form.
For more of Dr. Oz’s beginner’s guide to building healthy muscles, see 7 Reasons to Start Building Muscle Today and No Dumbbells Required: 5 Strength-Building Exercises You Can Do Anywhere.
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