Others take a twist on conventional aerobics classes from the Jane Fonda era — SPRI Step360 is the latest incarnation of the step class. Then there are the ones that combine elements of other classes, such as piloxing, a combination of kickboxing and the ab-focused Pilates workout.
At MAC Fitness in Harbor East, Heather Hatfield recently led a class through 30 minutes of boot camp drills inspired by the popular books and movie "The Hunger Games," in which "tributes" fight in a survival-of-the-fittest contest.
There was no bow and arrow like the one the protagonist, Katniss, used to shoot an apple and wow the judges. Instead, the class simulated the same archery moves with resistance bands, working out their shoulders and triceps.
Then participants got to feel a little of the pain Katniss endured when she burned her thigh in a forest fire. Like Katniss, participants hopped on one leg in a drill that took them across the room, stopping after each hop to touch the floor, leg still in the air.
"You have no use of your wounded leg," Hatfield said as class members made their way across the floor, grunting and grimacing. Their thighs were also burning by the end of three sets.
Class ended with everyone forming alliances, just as some of the participants did in the games to try to survive. The only difference is the goal: helping one another through a grueling ab session and surviving the class. They'll also get a ticket to "The Hunger Games" movie once they complete four of the classes.
Nicole Haller, a 40-year-old physical education teacher who works out just about every day of the week, said the class was tough, but it was fun to relate to the books.
Hatfield, who is 30, said that's what she was going for. "You want to give people something to focus on other than the exercises."
If you're looking for a more serene workout, Ultimate Watersports will begin offering paddleboard yoga just as soon as the water gets warm enough at Dundee Creek in Gunpowder Falls State Park. The area is surrounded by large trees that block the wind, so the water is always calm, said Ultimate Watersports president Hal Ashman.
But just because such yoga positions as the child's pose and sun salutations are done on calm waters doesn't mean the workout is easy, Ashman said.
Stand-up paddleboarding was popular before surfing but died off when people found it easier to paddle lying on their stomachs. The sport has come back in the past few years — first on the West Coast, then on the East Coast, and now with yoga.
Yoga on the paddleboard means a tougher core and abdominal workout because it's harder than balancing on land, Ashman explained. Paddling out to the spot where yoga will be performed will work other parts of the body.
"Your whole body is working," Ashman said. "You have to use every single muscle to stay upright and get that board to go."
The company introduced the sport as a pilot program last year and is offering the class for a full season in May. They'll offer free clinics on paddleboard yoga during Paddlefest May 12.
Even as gyms experiment with new classes, tried-and-true options like kickboxing, cycling and step remain popular.
Now the Bare Hills Racquet and Fitness Club is offering the latest incarnation of step: SPRI Step360.
Fitness fiends who began taking step classes in the 1980s and progressed to step on the BOSU ball may be attracted to SPRI Step360.