Walk into any gym, and you’ll likely encounter two basic kinds of free weights: the trusty dumbbells and the new kid on the block, the kettlebells. Both have their merits and devotees, but one question often persists: When it comes to getting results, is one better than the other? Here, experts weigh in on which to choose and when.

Best for…

Dynamic Movements: Kettlebells
When it comes to explosive, physical movements, kettlebells are king. If your goal is powerlifting, plyo improvements, or if you’re competing in a sport that requires explosiveness (like basketball or CrossFit games), research suggests kettlebells lead to greater gains.Transference of kettlebell training to strength, power, and endurance. Manocchia P, Spierer DK, Lufkin AK. Journal of strength and conditioning research / National Strength & Conditioning Association, 2013, Jul.;27(2):1533-4287.

Choose these for exercises that recruit several major muscle groups and involve moving in a big, significant way. Some typical kettlebell moves include snatches, cleans, windmills, Turkish get-ups, and of course, the kettlebell swing.

Swings are also great because they can spike your heart rate, providing cardiovascular as well as strength benefits, says Dell Polanco, head coach at BRICK New York. Unlike a simple curl or press, the kettlebell swing activates your entire posterior chain of muscles—your glutes, hamstrings, and erector spinae (back muscles), he explains.

Basic Movements: Dumbbells
“Dumbbells are great for a little bit of everything,” sats Nikki Reifschneider, the assistant director of fitness and personal training at the University of Miami. “You can start with more basic movements like a chest press, shoulder press, a row, or squats with dumbbells held at the shoulders.” The advantage is that you’re not swinging the weight around (like you do in a snatch or swing), making the moves a bit more straightforward, Reifschneider says.

Mixing up Your Workout: Kettlebells
“If you’re sick of doing burpees and mountain climbers, try kettlebells during a HIIT workout,” says Liz Barnet, certified trainer at Uplift Studios in New York City. Barnet adds that it’s easy to integrate kettlebells into a workout finisher—for example, 30 to 60 seconds of all-out effort swings to cap things off.

Newbies: Dumbbells
Stick to dumbbells unless you have instruction with kettlebells, Barnet says. In fact, all of the experts we spoke with emphasized that dumbbells are the best choice for weight training unless you’ve specifically worked with a personal trainer on kettlebells.

Improving Grip Strength: Kettlebells
Because the horn (handle) of the kettlebell is often thicker than a dumbbell, they can be ideal for increasing grip strength, Barnet says. “For instance, a bent-over row with a kettlebell can strengthen the grip and help prepare you for challenging exercises like pull-ups,” Barnet says.

General Fitness: Dumbbells
One study showed that, compared to dynamic moves with kettlebells, basic weightlifting exercises (think power cleans and squats) led to significantly greater improvements in strength over a six-week period.Effects of weightlifting vs. kettlebell training on vertical jump, strength, and body composition. Otto WH, Coburn JW, Brown LE. Journal of strength and conditioning research / National Strength & Conditioning Association, 2012, Sep.;26(5):1533-4287. In other words, if your goal is general strength and fitness, there’s nothing wrong with sticking to dumbbells—and there’s probably not an advantage to using kettlebells.

Adding an Extra Challenge: Kettlebells
“Kettlebells take the center of gravity about six to eight inches away from your hand, whereas dumbbells provide more stability,” Reifschneider says. This makes moves like a bottoms-up kettlebell press especially challenging because you’re working to lift the weight and stabilize it—so the bell doesn’t topple over and hit your arm. Trainers also love kettlebells because of that instability: They’re just like unbalanced objects you pick up every day. But with that added challenge, kettlebells do provide an unwelcome element of danger, so if you’re fairly new to exercising, stick with dumbbells.

Progressing in Weight: Dumbbells
It’s easy to make your workouts more challenging with a dumbbell. “You don’t have to use dumbbells in a slow, isolated push-press [movements],” Polanco says. “You could do hang cleans, squat cleans—all of those are explosive movements.” Polanco also says it’s OK to practice some of those explosive moves first with dumbbells before upgrading to a kettlebell. And remember, “to a certain extent, a weight is a weight,” Reifschneider says. “With any piece of equipment, you can make a workout challenging. It’s all about your creativity.”

Plus, kettlebells often don’t come in small size increments like dumbbells, Polanco says. Although lots of companies make kettlebells in other weights, depending on what your gym has available, it might be tough to find a “perfect fit.” On the other hand, most gyms readily stack dumbbells at five-pound increments, making them ideal for moving up in weight gradually.

The Takeaway

So which is better? Well, it depends. Newbies and those looking to perform basic strength movements at the gym should head toward the dumbbell rack, while CrossFitters and people doing explosive moves should grab a kettlebell. Choose which type of weight works with your exercise plan and fitness level, and never hesitate to consult a certified trainer for a personalized assessment if you have any questions.