Stipe Miocic moves fast — way faster than someone his size should.

The UFC fighter glides more than he sidesteps as one of his coaches, Arman Loktev, holds up two black punching bags that look like curved stereo speakers strapped to his forearms.

Miocic lets a three-punch combo fly that’s so quick, you never see the wind up. But the kick. Miocic’s right foot leaves the wrestling mat, his knee bends slightly, bunching up with power, and then explodes upward into the bags, which Loktev is now holding together to brace for impact.

Thwack! The vibration shakes the exposed rafters at Strong Style Mixed Martial Arts and Training Center in Independence where Miocic trains. It echoes like thunder in the no-frills business park gym.

About 20 feet away, a kid taking a karate class looks over.

“Again,” barks Loktev, a former MMA fighter who appears diminutive next to the 6-foot-4-inch, 240-pound Miocic.

He responds by flashing a left-right-left combo and another kick that lands like a steel beam.

Miocic, wearing fingerless MMA gloves, athletic shorts and a gray shirt that soaks with more sweat after each combination, is midway through the first of five five-minute rounds designed to simulate a full-length UFC bout. The combat sport mashes kickboxing, wrestling, jujutsu, karate, judo and more into a full-contact mixture of striking and grappling.

“Control my head,” Loktev barks again.

Miocic grabs him with two hands behind the neck and drives one knee after the other up into the punching bags.

A buzzer rings to stop the first round.

“It took me about two minutes to loosen up,” Miocic says to Loktev.

As Miocic stalks, head down, around the wrestling mat that stretches throughout the gym, Loktev drops the bags to give his arms a rest.

“I feel like I’m jelly,” Loktev says. “He’s very powerful, but he moves like he’s 155 pounds. It’s crazy.”

Forged of the same steely disposition as the suburbs where he grew up, Miocic is aw-shucks nice in a sport splattered in blood. He’s the opposite of movie-star handsome: good-looking with a squared Croatian jaw, fighter’s nose and short, mussed hair. A former college baseball player and wrestler, Miocic turned to MMA 10 years ago as a way to feed his competitiveness.

He became the UFC’s heavyweight champ May 14 after knocking out Fabricio Werdum. His next fight and first title defense happens Sept. 10 at Quicken Loans Arena against No. 1 contender Alistair Overeem, a powerful kickboxer who’s 28-11 in UFC matches.

Miocic may be a badass cage fighter with an affinity for F-bombs, but his wide smile and goofy nature make him easy-going and approachable. He’s the champion the city needs, the unlikely favorite who doesn’t boast or gloat and worked his way up UFC’s ranks while still working two part-time fire fighter jobs. When LeBron James says, “In Northeast Ohio, nothing is given. Everything is earned,” he’s talking about people like Miocic.

But as Cleveland knows all too well, winning is as fragile as Lake Erie ice in April.

Defending UFC champs have taken a beating in the last year. Since January, seven UFC champions have lost their titles.

Some of that’s due to the emerging sport’s volatility — one of its major selling points — where the slightest misstep can turn into a quick knockout or submission. As MMA grows, staying on top gets more difficult as more quality fighters join the ranks. And those paltry title defense figures can also be attributed to the increased demands on champions who are pushed to sell the sport and its pay-per-view model.

As UFC tries to climb the ranks of popular sports, the Land’s champ is a potential liability. Five years ago, MMA was niche. But as fighters such as Ronda Rousey and Conor McGregor appear on TV, in movies and on the covers of ESPN the Magazine and Self, the sport’s mass-market appeal grows.

In addition to being winners, Rousey and McGregor, one of the biggest trash talkers in a combat sport since Muhammad Ali, are well-known characters the UFC can sell. The result is a hybrid between the entertaining storylines of big-time WWE wrestling and the real results of boxing.

“How good someone is isn’t good enough,” says ESPN sports business analyst Darren Rovell. “A guy like Stipe is less marketable than a guy who has been a champion before and is currently not a champion.”

None of that matters to Miocic. Fame doesn’t drive him.

“I don’t give a f--- about the camera,” he says, sitting on the edge of a boxing ring at Strong Style. “I like having something I can share with my family and friends.”

While life has moved at the pace of his lightning-strike punches — batting practice with the Cleveland Indians, Cleveland Cavaliers playoff games, championship parades and a wedding to his girlfriend of four years, Ryan — he won’t let the whirlwind knock him out. Miocic started a two-session-a-day training camp for this title defense in late July.

“I feel f--king awesome,” Miocic says. “I feel ahead of the game.”