At the Clyde Recreation Center in Springville, the music is loud, the energy is high, and the sweat is real — often due to Bill Castillo’s MRT (Metabolic Resistance Training) classes. MRT is a fast-paced class built around short bursts of intense exercise and quick recovery. It’s not your average gym routine, and trainer Bill Castillo said he wouldn’t have it any other way.
“MRT stands for metabolic resistance training,” he explained. “Metabolic, meaning we’re speeding up your metabolism. Resistance means we’re using weights, bands, or bodyweight — any kind of resistance.”
Each class runs on a system known as EPOC (Excess Post-Exercise Oxygen Consumption), which creates an afterburn effect.
“You get your heart rate high enough that to bring it back down, it uses some fat from your body,” he further explained. “For the next 36 hours, your body uses fat as fuel to bring your body back to what’s called homeostasis, where your body’s back to normal.”
The result? A workout that doesn’t just test your limits, but one that keeps your body working long after you’ve left the gym.
Castillo sets up 15 to 20 stations around the room, each one targeting a different muscle group.
“It’s synchronized, so if at one station you’re doing lunges, that’s for the quads. The next
(station) is not going to be for the lower body; it needs to be for the upper body or core, so that [part of your body] has a break,” he said.
Participants move through the circuit in 30-second bursts, resting for 15 seconds before rotating to the next challenge. It’s designed to push, but never punish. And while the class is intense, it’s also inclusive.
“Ideally, it’s great for people who already lift or work out regularly, but I never turn anyone away,” Castillo said.
His 20 years of experience as a physical trainer help him modify movements for students of all levels.
“There are a lot of ways to modify it, and I keep observing (my clients) making sure they’re not lost or that they don’t get hurt,” he said. “The number one goal is safety first, and then the second is to have fun.”
That approach has helped make the class one of the center’s most rewarding. Over the years, Castillo has seen remarkable transformations.
“I have one student, when I’d have the class go running, she would walk,” he said. “She would be the last one to come back and everybody would already have started class again. She’s been coming for about six months or so, and now, she’s in the middle of the pack. She’s jogging. She thought it was going to hurt her knees and her back, but she’s loving it.
“People benefit from the class (for many reasons),” Castillo continued. “They’re able to pick up their grandchild or squat down low and play with their kids or something. … Before, they couldn’t do that.”
Between rounds, Castillo keeps the class moving with mini challenges—five burpees here, ten pushups there—and always ends with a cooldown stretch.
“They’ll say, ‘My abs were sore for three days. That was a good workout. Let’s do it again.’ I try to keep it different, fresh, interesting, funny, fun,” he said.
The roots of his approach go back to a conference in Las Vegas 15 years ago, where Castillo first heard about metabolic resistance training.
“I just started researching it, looking at ways to implement it and put it into a class where everybody would be able to do it,” he recalled, adding that In 2013 when the Provo Rec Center was looking for new fitness instructors, he pitched his idea for a class. “They said no one else was doing anything like it.”
Castillo’s classes are offered at the Clyde Recreation Center in Springville on Tuesday and Thursdays at 5 a.m. and 6 a.m. For more information, reach out to the center directly.
(Bill Castillo is bottom left with class participants.)
