No. 1 If you only do yoga, you're not challenging your muscles as much as you should
To build strength, muscles need to be challenged to their max. And while yoga can be strenuous it has its limits. "Although using only your body weight can be challenging when you first start doing yoga, your muscles quickly adapt, so the benefits diminsh over time.
No. 2 Strength training revs your metabolism
Your metabolism is the rate at which your body burns energy, or calories, to function. Whether your sleeping, eating or exercising, your body is torching calories-and if your metabolism is revving like a high-performance sports car rather than a 20-year old hooptie, you'll burn more calories without even trying.
No. 3 Weight training makes you more flexible
Yes, your read that right: o0 Stretching aren't the only keys to increasing your flexibility. In fact, research shows that strength training using your full range of motion may be even better than static stretching when it comes to building overall flexibility.
No. 4 Weightlifting can help maintain bone mass-maybe even more than calcium
When muscles contract, they shorten and pull on your bones, which stimulates bone growth. Since women can lose up to 20 percent of their bone density in the 5 to 7 years after menopause, boosting bone strength is crucial. And weight training is one of the most effective ways to do it.
No. 5 You'll build strength that will help prevent common aches and pains
Sitting at your computer all day, lifting heavy grocery bags and other everyday activities can throw your body out of whack. Yet the stronger you are, the less chance you have of injuring yourself while performing these daily tasks.
Natural Health. (2011, September/October). Heavyweight, pp.74-78