When you design a “sport” intended to give defenseless participants brain injury you unsurprisingly get brain injury. A lot of it. Those are the findings of a recent research letter reviewing objective signs of concussion amongst participants in PowerSlap.
These findings are important because the promoters of PowerSlap try to emphasize its relative safety compared to other regulated combat sports when expanding in to new jurisdictions. This recent research speaks otherwise.
The research was published in the peer reviewed journal JAMA Surgery and is titled “Video Analysis of Concussion Among Slap Fighting Athletes“. The authors reviewed 78 slap fights. They looked for objective signs of concussion among the participants (and it is worth noting that concussions can occur with only invisible subjective symptoms and no objective signs). They found that 1 out of every 3 slaps led to objective concussive symptoms. An astounding 78% of the participants displayed signs of traumatic brain injury. Far more than in boxing, MMA or any regulated combat sport.
The full study reads as follows:
Slap fighting is a fast-paced combat sport wherein athletes strike each other in the head with open hands and matches are largely scored by points or knockouts. Power Slap,1 a slap fighting promotion that has offered a platform for this largely underground sport, was first televised in January 2023 and has drawn extensive criticism from both medical and nonmedical personnel.2 Worryingly, the promotional video for Power Slap3 features several contestants exhibiting signs of concussion. While there is a general consensus regarding the severity of this sport, to our knowledge, a quantification of the concussion risk has yet to be reported. The goal of this study was to identify signs of concussion among slap fighters by performing a video analysis.
Methods
In this cross-sectional study, the rules of Power Slap were reviewed as presented on the Power Slap website,4 after which online videos of slap fighting events were viewed. Outcomes of legal slaps as well as illegal slaps (ie, fouls) from season 1 and main events 2 to 5 were reviewed. Offensive and defensive fouls were assessed when the striker or defender, respectively, was unfairly advantaged; the types and definitions of each foul are explained in detail on the Power Slap website.4 Four reviewers (R.S.L., R.P.K., M.R.K., and M.J.S.) observed for visible signs of concussion as defined previously.5 Definitions were modified to suit the Power Slap environment (Table). Only one sign was necessary to indicate that a concussion was sustained. Analyses centric to sequences, defined as a series of slaps against the same defender within a single match, were also performed. Interrater reliability was assessed using Cohen κ statistics. Agreement between both reviewers was required to account for a visible sign of concussion (Figure).
In accordance with the Common Rule, this study was exempt from the need for institutional review board approval or informed consent owing to the use of publicly available data. The study followed the STROBE reporting guideline.
Results
A total of 78 fights were analyzed, comprising 333 slaps and 139 sequences among 56 contestants. Concussive signs were observed after 97 slaps (29.1%) and 72 sequences (51.8%). Of the 56 contestants, 44 (78.6%) had at least 1 concussive sign, and 20 instances of second impact (ie, a contestant showing a visible sign of concussion after having shown signs after a previous slap) were observed. Among slaps in which an offensive foul was assessed, 13 of 56 (23.2%) and 2 of 20 (10.0%) resulted in a concussive sign or second impact, respectively. Slaps with a defensive foul did not result in any visible sign of concussion. Contestants who displayed a visible sign in a sequence lost 54 of 72 times (75.0%). The most common signs included motor incoordination (interrater reliability, 0.78), slow to get up (interrater reliability, 0.78), and blank and vacant look (interrater reliability, 0.74) (Table).
Discussion
The findings of this cross-sectional study suggest that slap fighting may induce traumatic brain injury in contestants, with potential for long-term consequences. The risk is further augmented given that the contestants must stand defenseless, allowing their opponents to achieve complete and precise contact with their heads during each offensive blow. Therefore, there must be a high surveillance when evaluating such athletes both acutely and on long-term follow-up.
This study has certain limitations, including the small sample size. In addition, using video analysis to identify signs of a concussion may be a subjective means of assessment. As such, agreement was required between the reviewers to prevent individual bias in the findings. Slap fighting may be a more grievous combat sport than previously assumed, and strategies to prevent neurological demise among its participants should be pursued.
Combat Sports Law 
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This viral slap study led me to your site. Your link to the study showing bareknuckle boxing has less concussions than boxing and mma led me down a rabbit hole. What I found is that all the concussion studies involving boxing and mma were from video review. Same with this slap study.
This slap study cites this limitation along with small sample size. Because of this, I feel like we can’t really take the conclusion seriously for any studies that did not involve evaluating concussion signs are done in person by a medical professional. I’m sure a medical professional might argue the results would be similar if it was conducted in-person, and I don’t really doubt it would at least be in the same ball park.
Every American football concussion study only involved in personal evaluation. And props to the people who did the bareknuckle study because that study was in person evaluation as well.