Kettlebells are the trendiest thing in weightlifting since protein shakes. But traditional weights are still superior when it comes to maximizing your strength, argues a new study from California State University, Fullerton. Kettlebell experts say the benefits of the oddly-shaped weights extend far beyond strength gains—if you know how to use them.

The Cal State team asked 30 men to train with either kettlebells or traditional weights twice a week. After 6 weeks, the traditional-weight group had boosted their squat max 14 percent—an average of 18 pounds—compared to just 4 percent (5 pounds) among the kettlebell lifters. The gains were similar when the researchers tested for upper-body strength improvements.

But there’s a catch: The old-school-weights group completed sets of traditional strength-building exercises like pull-downs, power cleans, and squats. The kettlebell group completed the same number of sets of various swing movements and goblet squats—exercises not designed solely to build strength. The traditional weights group also lifted more iron than the kettlebell users.

More from MensHealth.com: The Kettlebell Exercise You Must Try

“We tried to use the kettlebells the way most practitioners would use them, emphasizing technique and using explosive movements,” explains study author Jared Coburn, Ph.D., a professor of kinesiology at Cal State, Fullerton. Coburn says it’s not surprising kettlebell strength gains were smaller than those resulting from traditional resistance exercises. You can put 300 pounds on a barbell—something you just can’t do with kettlebells, he says.

“There is no better tool for adding load than the barbell,” says Dan John, a national masters champion in Olympic lifting and a strength coach in Draper, Utah. For those strength-building exercises that can require substantial weight—such as the bench press, dead lifts, squats, or snatches—John says only the barbell can meet the resistance needs of some lifters. (Not that kettlebells are useless with these exercises. Take a look at this awesome move, the kettlebell squat and curl.)

You can use kettlebells or dumbbells interchangeably for some exercises, such as bicep curls or lateral raises, John adds. (Read more about when to swap your dumbbells for a kettlebell here.) But the key to unlocking the power of the kettlebell is to use it differently than you would traditional weights, explains Jason Brown, C.S.C.S., owner of Kettlebell Athletics in Philadelphia.

“If your goal was just to get strong, you don’t need kettlebells,” Brown says. “If your goal is to burn fat, increase power endurance, and get strong, then kettlebells are a great tool.”

While traditional weights are all about low reps and more weight, kettlebell-specific exercises are designed for higher, faster repetitions performed for a minute or more. (For even more ways to get leaner, stronger, and more athletic, be sure to check out The Athlete's Book of Home Remedies for thousands of quick fixes to your routine.)

You’ll activate dozens of muscles instead of just a few, which increases your body’s fat-burning metabolism, Brown says. You’ll also improve your power endurance, or your muscles’ ability to repeatedly perform fast, powerful movements during an extended period, Brown explains. Think of jumping to shoot or block a shot in basketball late in a pickup game, or swinging a golf club after 16 holes.

It all depends on your goals. If you’re trying to build a bigger chest, look to barbells and dumbbells—like Todd Durkin, C.S.C.S., prescribes in the Big Chest Workout.

For a full-body routine that burns fat, adds muscle, and gets you in shape for your weekend Ultimate Frisbee games, try the Ultimate Kettlebell Workout. And if you only add one kettlebell exercise to your regular routine, make it the kettlebell swing. This exercise activates your hamstrings, back, and posterior chain of muscles and you’ll improve your speed, flexibility, and core strength, says David Jack, a Men's Health advisor and director of Teamworks Fitness in Massachusetts. Click here to see how to do it with perfect form.

More from MensHealth.com: The 9-Minute Kettlebell Workout