In combat sports a fighter’s goal is to render their opponent unconscious while minimizing damage to themselves.

Physiology of KO:

Rotational acceleration of the brain. Shearing forces on the brain that strain the pathways in the upper brainstem. Additional impact can occur when the brain strikes the skull following impact.

Factors that influence KOs:

  1. Force generated by the attacker.
  2. The type of strike used: Rotational acceleration tends to cause more disruption to the brain compared to linear acceleration (Barth 1989). This may be a hook punch or straight punch if the attacker has the proper angle.
  3. Neck Strength: A fighter aware of a strike can brace for impact and roll with the strike. However this only helps when the defender is aware of the strike (Neumann). *A very common saying in combat sports is that the most devastating strike is the one that you don’t see coming.
  4. Mandible shape: The chin is considered a KO button due to the proximity it has with the brainstem. Some fighters may have an anatomical advantage with a large jaw. *This is based on experience as I was unable to locate any research to support or refute this claim.
  5. History of concussions: The brain can only absorb so much punishment. With a history of concussions and repetitive submaximal strikes a fighter’s brain loses the resiliency it may have once had.
  6. Fatigue.

An example of this was in the boxing bout Floyd Mayweather vs. Conor McGregor.

McGregor had early success, however as he exerted himself and Mayweather continued to pressure, the irish fighter started to fatigue.

As fatigue set in, Mayweather was able to land multiple clean shots. While it was clear that Mayweather was the better boxer I would have liked the bout to have continued until he could have cleanly finished the match.

Dr. Mike Piekarski, DPT
BJJ Brown Belt
Former MMA Fighter

Barth, J. T., Alves, W. M., Ryan, T. V., Macciocchi, S. N., Rimel, R. W., Jane, J. A., & Nelson, W. E. (1989). Mild head injury in sports: neuropsychological sequelae and recovery of function. Mild head injury, 257-275.
Neumann, D. A. Neumann, Kinesiology of the musculoskeletal system: Foundations for Rehabititaion.