ON SATURDAY May 2nd two of the world's most marketable boxers, Manny Pacquiao of the Philippines and America’s Floyd Mayweather, will face each other in a fight. Undoubtedly both will go in to the match hoping to win it with a definitive strike. Mr Mayweather, an undefeated professional boxer, takes particular delight in flattening his opponents (26 of his past 47 wins were knockouts). What is a knockout punch and how does it work?
A knockout blow is a form of cerebral concussion, a common scourge in other sports such as American football, football and hockey. But in boxing, to land the killer blow is a constant endeavour as much as it is an occupational hazard. A good punch is a result of the entire body working in tandem. It can start at the feet, work its way up the rotating torso, and force itself through the shoulder muscles onto the fist. It need not always be forceful. For instance, former heavyweight champ George Foreman, who won 68 of his 76 bouts by knocking his opponents off their feet, relied on catching them off-guard with a flurry of short-arm slugs. Joe Frazier and Mike Tyson, on the other hand, were known to put their entire body into their punches, to devastating effect.
So what happens in those final few moments between the time the jaw takes a hit and the legs give away? The start of the process is easy enough to explain. In most cases, the impact from a punch or series of punches causes the brain to move inside and smash up against the skull. Roundhouse punches and hooks are particularly menacing. The arc at which the gloved fist meets the opponent's jaw sends the head (and hence, the brain) into a spin. Just as a passenger on a motorbike would slide in his seat and bump into his rider when he brakes without warning, a blow to the head causes the skull to shift and the brain to catch up before colliding against it. The fall when a dazed head hits the mat can also contribute to the trauma. It is less clear how exactly that trauma contributes to unconsciousness. One possibility is that the impact can cause the massive release of important brain chemicals called neurotransmitters, which normally help the brain send signals. This can mess with the cellular chemistry of the brain and cause neurons to fire out of control. Overwhelmed, the brain may simply shut down—reboot, effectively—until chemical balance can be restored. Other mechanisms might also cause a knockout. The carotid artery, which provides blood to the brain, has a reflex area known as a sinus, which helps regulate the flow of blood and oxygen to the head. A sharp knock on the jaw could jolt that sinus, altering blood and oxygen flow by enough to generate a loss of consciousness.
While they can’t plan for it, fighters look to diffuse the impact of potential knockout punches by training hard. A muscular neck is key to ensure that the head, upon being hit, does not bob back and forth like a dandelion in the wind. A strong jaw bone helps, too, and so do clever fighting techniques. Ironically, the very boxing gloves that protect the pugilist from cuts and bruises—a throwback to the bare-knuckle era—are responsible for damaging head injuries. Heavily padded gloves favour the hitter who would have been loath to punch with the same ferocity using his bare knuckles; the bones of the skull are stronger than those in the fist. But the 10 ounce (283-gram) gloves help knockout artists like Mr Mayweather show off their skills. It makes business sense too; the “fight of the century” is set to rake in $400m. On Saturday high rollers at the MGM Grand casino in Las Vegas and millions of TV viewers will bay for a knockout—not least Mr Mayweather’s father (and coach) who taught him to throw punches when he was just nine months old.
