From Health magazine
Kettlebells—those hand weights that look like teakettles—have been picking up steam lately in gym classes and personal-training sessions. But are these cast-iron weights a best-kept fitness secret or an injury waiting to happen?

How they work
Most kettlebell workouts start with a few warm-ups sans the bells to get your joints ready for swinging. Then, using a bell of usually 15 pounds (they range from 8 to 90 pounds), you do a combination of static strength moves (like shoulder presses, squats, or rows) and active ones (swinging the bell with one arm from between your legs to above your shoulders, for example); you end with stretching. Some class instructors keep your heart rate up by having you swing the bell constantly while doing simple dance steps. Youll actually use the bells for about half of a typical hour-long session.

The bottom line
If you dont mind taking a little time to learn the right form, kettlebells offer a variety of challenging, full-body moves both in classes and during personal training. After my session, I could feel the results in my legs, core, and arms.

Kettlebell workouts can definitely take the place of your regular strength-training routine. Classes are a good option if you cant spring for a one-on-one session (about the same price as any hour with a trainer), though youll need to take a beginner class or get form pointers from the instructor ahead of time. Also, its best to use lighter weights during your first few classes.

The cost
A few years ago, kettlebells could go for more than $100—but now you can get them starting at around $30, depending on weight. If you don't want to buy your own, check with your local gym for classes and personal-training sessions; several Equinox clubs across the country offer kettlebell classes.