When the open-handed blow is delivered, there’s a sharp report and the reaction can be dramatic. Some fighters barely move, while others stumble backward or fall to the floor. Some are knocked out.

UFC President Dana White is selling slap fighting as the next big thing in combat sports, putting his money and the resources of one of the world’s foremost mixed martial arts organizations behind the Power Slap League. The Nevada Athletic Commission has sanctioned the league for competitions in Las Vegas.

“It’s a home run,” said White, who is among several UFC officials involved in the league.

Some slap-fighting beatdowns have gone viral, including a video from eastern Europe showing a man who continues to compete even as half of his face swells to seemingly twice its size. Such exposure has led to questions about the safety of slap fighting, particularly the risk of chronic traumatic encephalopathy, or CTE, a degenerative brain disease believed to be caused by repeated blows to the head. A former chairman of the commission, which regulates combat sports in Nevada, says approving the league was a mistake.

Chris Nowinski, cofounder and CEO of the Concussion Legacy Foundation, agrees, calling slap fighting “one of the stupidest things you can do.”

“There’s nothing fun, there’s nothing interesting and there’s nothing sporting,” Nowinski said. “They’re trying to dress up a really stupid activity to try to make money.”

White and the competitors remain unfazed, comparing commentary on slapping to the negative reaction the UFC faced in its infancy more than 20 years ago.

“I think it’s definitely overblown with the topics of CTE and the damage that we’re taking,” said Ryan Phillips, a Power Slap League fighter. “I think a lot of people still just don’t understand that it’s still a slap.”

Concerns about concussions leading to CTE, which can cause violent mood swings, depression and memory loss, aren’t confined to combat sports. The disease has shown up in the brains of former rugby players, and the NFL and college football have taken steps to cut down on blows to the head by changing rules regarding tackling and other hits. CTE can only be detected during an autopsy.

Despite the naysayers, White said he believes slap fighting will follow a similar trajectory to mixed martial arts, which the late Sen. John McCain referred to as “human cockfighting” in 1996, when the UFC didn’t have weight classes or many rules. McCain’s criticism helped force the organization to become more structured, leading to its widespread acceptance.

White said the ratings of the TBS reality show “Power Slap: Road to the Title” bear out the early popularity of what to many is still a curiosity.

White said he realized there could be a market for the sport in the U.S. when he clocked the millions of YouTube views of slap fighting videos from eastern Europe in 2017 and 2018. The videos were often poorly produced, the slap matches unregulated. White became convinced that fights with written rules and shot with professional video equipment could convert many internet viewers into dedicated, paying fans.

The Nevada commission gave slap fighting some much needed legitimacy when it unanimously sanctioned the sport in October and a month later awarded White a license to promote it.

But White’s enterprise was hampered when he was captured on video slapping his wife on New Year’s Eve. White apologized, but has acknowledged it damaged efforts to get the league off the ground. White is no newcomer to controversy: Former UFC fighters Kajan Johnson and Clarence Dollaway filed a lawsuit in 2021 against Endeavor, the organization’s parent company, alleging that UFC takes an inordinate share of the profits.

But White is charging ahead.

Three qualifying events have taken place at the UFC Apex in Las Vegas, ahead of the March 11 telecast on the streaming platform Rumble in which champions will be crowned in four weight classes.

Power Slap fights are typically three to five rounds. The fighters take turns hitting each other in the face with an open hand, and those on the receiving end stand with their hands behind their backs. A fighter has up to 60 seconds to recover and respond after receiving a blow. Fighters can earn up to 10 points based on the effectiveness of the slap and the defender’s reaction.

Fights can end in a decision, knockout, technical knockout or disqualification, such as for an illegal slap. All slaps are subject to video review. Each event has two referees and three judges.

Also present are a supervising doctor and a physician or physician’s assistant, plus three EMTs and three ambulances. White has touted the safety record of the UFC, but has not talked specifically about injuries in the Power Slap League.

White says slap fighting is safer than boxing or mixed martial arts because each contestant usually takes only three blows per bout. In boxing, White said, that number could be 400 or more, and that doesn’t include the shots taken during sparring. There is no sparring in slap fighting, he noted.

Nowinski of the concussion foundation said while there may be no sparring in practice sessions, that doesn’t mean it doesn’t happen elsewhere. He said comparing boxing to power slapping is misleading because slap fighters take a full blow each time.

“You can slip (boxing) punches,” Nowinski said. But in slap fighting “you’re taking out everything that’s interesting to watch and everything sporting (from boxing) and just doing the brain damage part.”

Nowinski said slap fighters don’t make enough money to justify the risk. The Power Slap League wouldn’t disclose how much it pays fighters, but said in a statement that participants are compensated for every match and can also earn “appearance fees” and “additional discretionary bonuses.”

Stephen J. Cloobeck, who was chairman of the state commission when it sanctioned slap fighting, said White and former UFC CEO Lorenzo Fertitta sold him on the legitimacy of the sport.

“I made a mistake,” Cloobeck said. “I’m not happy about it.”

The commission recently approved amended rules to better define what constitutes a legal slap in an effort to minimize serious injuries.

“The No. 1 thing is the health and safety of the fighter,” commission Chairman Anthony Marnell III said at a Feb 15 meeting. “Always has been, always will be.”

But he went on to say: “It seems like there is a market for this, whether you like it or not.”

Phillips, the slap fighter, said participants can defend themselves without losing points, such as rolling away before the hand makes impact.

And the fighters know if they lose the coin toss and get slapped first, it will hurt.

“I know what’s coming,” fighter Vernon Cathey said. “I’m tensing up. There’s a lot of stuff I can do to protect myself.”