Group fitness classes have exploded in recent years, both at nationwide gym chains and boutique fitness clubs. HIIT (high-intensity interval training) classes are up 63 percent since 2013, for example, and barre offerings have grown a whopping 141 percent in that time, according to the International Health, Racquet & Sportsclub Association. With new, totally diverse studios popping up all the time, figuring out the benefits of each can be confusing—to say the least. So we’ve broken it down for you. Whether you want to drop a couple pounds or limber up, read on to find the best fitness trend to meet your goals.

IF YOU WANT TO...

1. LOSE 5 POUNDS  

Try: A HIIT class, like those offered at Kore and Refine Method in New York City.

If you’re already in good shape and just need to shed those last few pounds, “It’s time to up the intensity!” says Certified Strength and Conditioning Specialist Mike Dovanavik, a Los Angeles-based personal trainer and creator of the Extreme Burn workout series. “With a HIIT class, your heart rate will stay elevated throughout the whole session. Plus if you go hard enough, you’ll continue to burn calories up to 48 hours after the session is over.”

2. LOSE 50 POUNDS 

Try: A combo of weight training and cardio, such as Orangetheory, Barry’s Bootcamp, or Shred 415, which all alternate intervals on the treadmill with resistance work.

“Cardio will build up your cardiovascular endurance and burn more calories per minute,” says Dovanavik. “And the focus on strength training will build lean mass, which ultimately burns more calories in the long haul.” 

3. GET STRONGER 

Try: A class heavy on strength training, like CrossFit.

Not into the heavy barbells? HIIT classes with lighter equipment are great for strengthening muscles, too. “When completing HIIT workouts with only your body weight, it’s most beneficial in conjunction with some loaded strength exercises,” says Lisa Niren, trainer at the PE Club. “Weight training and HIIT workouts allow you to preserve your muscle while ensuring that weight loss comes from fat stores.” 

4. GET TONED (BUT NOT BULK UP) 

Try: Circuit training or barre.

Okay, these two sweat styles are crazy-different, but they can help you achieve the same goal. If you’re into high-intensity workouts, circuit training in a class like Orangetheory or Sweat Garage in Los Angeles keeps you “moving from exercise to exercise in order to keep the heart rate and calorie burn up,” says Dovanavik. “So you’re slimming down and sculpting but never truly focusing on building muscle mass.” In other words: You won’t bulk up. If you prefer a more low-key pace, a barre class—like those at Exhale, Pure Barre, and Pop Physique—incorporates tons of reps with light dumbbells, small stability balls, and bodyweight movements to tone sleek muscles.

5. HAVE MORE ENERGY 

Try: A pump-you-up cardio class to get the feel-good endorphins flowing.

Treadmill sessions are trending right now (at gyms like Equinox and boutique studio Mile High Run Club), and group-cycling classes at boutiques like SoulCycle, Peloton, and Flywheel attract devotees for their high-energy offerings. After sprinting or spinning, says Donavanik, “your heart will pump more efficiently, and your lungs will be able to work at a greater capacity—so you’ll be able to better absorb and utilize oxygen.” Plus, “having tools in front of you, like your cadence and resistance on the bike, allows you to push yourself at higher rates for longer times—and actually see the results,” says Cody Rigsby, coach at Peloton in New York City.

6. INCREASE YOUR FLEXIBILITY 

Try: Yoga and foam rolling.

Most gym chains offer group yoga practices, but several boutiques have popped up recently, too—companies like Core Power (with locations in cities like Minneapolis and Denver) and Y7 in NYC and L.A. are super popular. “These classes focus on movements that train your muscles and joints in a large range of motion,” says Dovanavik. “And foam rolling will also help aid in smoothing out muscle and breaking up knots. That helps you move more freely without feeling restriction.” The trend is so big, chains like Equinox and LifeTime Fitness have started offering rolling and stretching classes to give your body some R&R.