The Science of a Knockout

Boxing fans live for the thrill of a knockout punch. But that KO comes at a steep physical price for the victim.

Right jab, left hook, right jab, and then ... bam!  Knockout.

There is nothing more exhilarating for a boxing audience than to see a fighter hit the mat in a knockout. But being on the losing end of a KO punch can damage a lot more than a pugilist's pride—research suggests that the blows that cause knockouts can be debilitating to a boxer's short and long-term health.

Repeated blows to the brain can cause chronic damage such as personality changes and dementia. If the punches have enough impact to cause uncontrollable brain swelling or hemorrhage, the fighter could even die.

So what causes a knockout? Concussions, and lots of them. While it often seems as though the effect is caused by a single well-placed shot, it is usually the result of many quick punches. Each punch creates a concussion (technically defined as any head injury that causes a disruption of neurological function), and each concussion brings the boxer closer to a state of darkness.

Here's how it happens: The body contains dissolved sodium, potassium and calcium, collectively known as electrolytes, which are responsible for conducting impulses along neurons. Every time a fighter receives a blow to a nerve, potassium leaves the cell and calcium rushes in, destabilizing the electrolyte balance, while the brain does all it can to keep these levels in balance. With each successive blow, this balance becomes harder and harder to maintain, and more and more energy must be spent in the process. When the body reaches the point where the damage outweighs the body's ability to repair itself, the brain shuts down to conserve enough energy to fix the injured neurons at a later point.

"After a brain injury, the heart must supply sufficient blood flow for the brain to repair itself. If the demand outweighs the supply the brain then shuts down and leads to an eventual loss of consciousness," says Anthony Alessi, M.D., a neurologist and ringside physician for the Connecticut State Boxing Commission. "That's when I know to end the match, because if we keep going the fighter is going to die."

Surprisingly, the boxer's feet are often the first clear signal that he is on the verge of being knocked out.

When the neural networks that emanate from the cerebellum (the part of the brain responsible for coordinating motor activity) are disrupted by a concussion, a fighter loses his ability to coordinate foot movements.

"They become flat-footed, which is the inability to adjust. Boxers can't move forward or backward quickly," Alessi says. "As you watch their feet, you realize that the same lack of coordination is going on in their upper extremities in their hands. And eventually they are unable to defend themselves."

Once their feet start to go, they are often just a single punch away from a knockout.

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