Spend enough time in the Pearl District and you'll begin to see the pattern: names that indirectly reference energy, abstracted images of lotuses, glass doors where packs of tall, 27-year-old women enter on the hour. Interiors are airy, sparsely decorated and heavy on the concrete, Marie Kondo meets brutalism. There are a lot of inspirational slogans, a lot of #branding, and a lot of money. Everyone is beautiful. Everything is beautiful.

Yes, these new group fitness classes can be intimidating. It's why I confined my routine exercise to solitary activity at my local 24 Hour Fitness, cynically dismissing these newfangled studio classes as expensive fads, free from the shame of getting torched on an exercise bike by someone my mom's age.

But these new, hyperspecialized studios are popping up across Portland, mirroring the nationwide growth in boutique gyms, which accounted for 42 percent of 54 million gym memberships across the U.S. in 2015. Clearly, there's more to these studios than meets the ab. After attending classes at six gyms across Portland, I learned I was wrong to discount them so fast.

I found myself working much harder, the pace of the class ratcheting ever skyward by ecstatic trainers. I was too focused, or too entranced by the sight of 24 people moving in unison, to feel self-conscious. I left almost every class in a great mood. The new wave of Portland group fitness—whether a bicycle-based health rave or a bewildering run between rowing machines with three women named Becky—is wonderful.

If you're looking to get into better shape this year, consider starting it with a survey of local group fitness classes.

Pyrolates at Firebrand Sports
500 NW 14th Ave., firebrandsports.com. First class $15.

The gym: Firebrand is clean, modern and serious, exemplified by its tidy red-orange-yellow branding and glowing neon sign. It offers three workouts: the Pilates- and yoga-influenced Pyrolates, the cardio- and ballet-style FireBarre and spinning- and ballet-based Bike + Barre.

The workout: Pyrolates, designed by Los Angeles fitness guru and Portland State alum Sebastien Lagree, is a series of body-weight resistance workouts performed on a body-sized device called a Megaformer—basically a yuppie torture rack. Lagree's workouts are hugely popular in Southern California and a reported favorite of Kim Kardashian and Michelle Obama. You'll need grip socks, which Firebrand sells for $18, with a 15 percent discount for your first pair.

Difficulty: 5/5.

In Pyrolates, you'll primarily use your abdominal muscles to perform slow, gentle movements on or through the Megaformer's mobile central platform, which uses bungee cords to provide resistance. This translates to brutal, muscle-shaking, sweat-dripping intensity from the first moments of the workout. I've never been set on fire and left to burn in slow motion for 50 minutes, but I imagine it feels similar to inching my kneeling, quivering body forward and back with two handheld pulleys. I was so exhausted that I could barely string a sentence together for an hour after this class.

Most hellish part: "Pulses," tiny back-and-forth movements that finished off most exercises, depleting the targeted muscle of its last drops of energy and replacing it with white-hot pain.

Full Body BurnCycle at BurnCycle Pearl
910 NW 10th Ave., burn-cycle.com. First class $15.

The gym: Created by Portlander Jessi Duley, and now expanded to Lake Oswego (4811 Meadows Road, No. 109), BurnCycle is a spinning class not to be confused with the extremely popular NYC-based SoulCycle. When you pass through the doors, you'll find a small, windowless exercise studio packed full of stationary exercise bikes.

The workout: You don your cycling shoes (rentals are free with the first class), teeter over and strap into your bicycle. Before you begin, your instructor explains that you'll bike along to the beat of whichever song is queued up, mostly in a half-standing, half-crouching position, for 45 minutes. You'll intermittently incorporate other cycling positions, crunchlike movements and some arm exercises with light dumbbells.

Difficulty: 4/5.

By the way, you're going to be doing this workout in the dark, about 18 inches away from people on every side of you. As soon as the music begins—a trancier variation on exercise house with a distinctly nostalgic bent—the lights dim and your instructor begins enthusiastically screaming instructions. You and your classmates will sometimes cheer as you peddle. If this sounds bewildering, it is. You're to dip and crunch to the beat of the music, and you will botch this maneuver several times before you correctly execute it, joining in glistening tandem with your classmates. You'll exercise in intervals, sometimes at a hamstring-shredding full bore, other times at a not quite leisurely pace, enshrouded in darkness and sweat fog, the only light sneaking in from under the doors. Once you get the feel for the class, you'll begin to enter a quasi-euphoric state—it becomes a health rave.

Most hellish part: You're in a pitch-black, sweltering, cramped box with a guy screaming at you over blaring music.

Orangetheory Lloyd District
1107 NE 9th Ave., portland-lloyd-district.orangetheoryfitness.com. First class free.

The gym: From the beaches of Fort Lauderdale to a sparkling high-rise in the Lloyd District comes one of the most popular new fitness classes in the country. Orangetheory splits the class in three groups, assigning each to a set of treadmills, rowing machines or free weights in a sizable studio. The class will rotate through each station in the roughly hourlong workout, each client wearing a monitor that tracks heart rate, which is displayed on televisions in the studio, sports bar style.

The workout: Company founder Ellen Latham designed Orangetheory based on a concept called "excess post-exercise oxygen consumption," or EPOC. The idea is that if clients can get their heart rate above 84 percent of maximum for at least 12 minutes of the workout, they'll enter this EPOC state and burn more calories than they normally would for 36 hours after the class. Thus, the heart-rate monitors track how long you spend in this range, which is designated by the color orange on the screen. How they get you orange? Mostly through interval-style cardio training on the rowing machines and treadmills.

Difficulty: 4/5.

The difficulty of the exercise is 3/5, but trying to figure out what is going on is so confounding that Orangetheory gets a bonus point. Before we began, the instructor rocketed through an explanation of how to adjust the machines and how the interval periods in the class would work. As Orangetheory has one instructor managing three groups of people, I immediately lost track of what I was supposed to be doing. The instructions are too jargony to be decipherable.

Most hellish part: Trying to figure out how fast or hard I was supposed to be doing anything, until out of frustration I just ran or rowed at whatever intensity I felt like. I nonetheless ended the workout with 14 minutes in the orange zone. Success?

Drench at Studio X
2839 SE Stark St., studioxfitness.com. $20 for up to four classes for two weeks.

The gym: Between Baby Doll Pizza and Bonfire Lounge is an inauspicious black door. Enter a long, orange-walled hallway and then go through double doors to an austere, concrete-walled studio packed tightly with squat racks, ropes and weights. A vintage VHS exercise tape lies alongside The New York Times on a small table. In this and two other studio gyms, Studio X offers small, hourlong classes covering cardio, power lifting, suspension training, as well as yoga, personal training and massage.

The workout: Drench is a boot camp-style workout that packages small groups of body weight- and light weight-based exercises, running you through them consecutively in circuits with short (10-second) bursts of rest in between exercises and slightly longer (1-minute) rests between sets. Do this for about an hour.

Difficulty: 4/5.

Things start easy enough: bouncing a weighted ball off of a wall into a squat, then some assisted pull-ups off of a giant rubber band. Later, you'll whip some inch-thick ropes around, and round things out with kettlebell cleans. Forty minutes in, you're heaving, deliriously trying to squat-jump with a medicine ball over your head, begging for death, while the trainer personally tells you how to fix your form.

Most hellish part: The bear crawl, an exercise in which you bend your knees to contract your abs, then crawl on all fours across the ground, is significantly more difficult than it sounds.

Barre3 Pearl
1000 NW Marshall St., barre3.com. Single class $23.

The gym: Founded in Portland in 2008 by Sadie and Chris Lincoln, Barre3 now sports over a 100 franchises as well as a lifestyle magazine (b3) and online workouts, available through subscription. Its flagship studio in the Pearl looks out on Tanner Springs Park and sports a large play area for children.

The workout: Barre3 combines ballet movements, oftentimes performed on the ballet barre (handrail) that runs across the studio's walls, with cardiovascular exercises, yogalike stretches and some light dumbbell movements. You won't need shoes and may wear grip socks.

Difficulty: 2/5.

Barre3 is not easy: You're going to do a lot of squats, suspend a lot of limbs in the air and work your core until you're heaving. I was sweating, a lot, by the end of the class.

Most hellish part: The pulsing. You hold a left leg out for long enough it starts to burn, then move it up and down an inch for even longer until you're gritting your teeth hard enough to crack them.

1804 NE Martin Luther King Jr. Blvd., pil-oga-robic.com. First class free.

The gym: A portmanteau of Pilates, yoga and aerobic, Pil-oga-robic hosts a variety of body weight- and light weight-based exercise classes that blend the aforementioned techniques in varying proportions and intensities, also offering personal training. Its spacious, wooden-raftered studio stands out in a Portlandy manner.

The workout: Pil-oga-robic is mostly body weight-based, less focused on maintaining particular poses than on keeping moving across the gym or through a series of poses. It's more boot-camplike than Barre or Pyrolates, but less aggressive than Drench.

Difficulty: 1/5.

As I grapevined across the studio with my older, comparatively diverse classmates, I realized Pil-oga-robic was the only class I attended that was closer to a fun PE class than exercise hell. The first half of the class consisted mostly of robic—think body-weight lunges across the floor—with the Pil-oga coming later. Although it was a little difficult to follow as we quickly shifted through the movements (I've never attended a yoga class), the instructor was clear and the exercises intuitive. I broke a sweat but left the studio refreshed.

Most heavenly part: The class wrapped up with the instructor dimming the lights for a stretch-down, during which she made the rounds to every student, anointing our heads with a eucalyptus-scented oil that made the world smell beautiful for hours afterwards.