In a perfect world, a highly trained, heavily muscled man would not punch you in the head.
Fortunately for most of us, the world is indeed perfect in that one small way. But most of us aren’t boxers. For those who are–say, Floyd Mayweather Jr. and Manny Pacquiao, who square off this weekend in a matchup dubbed “the fight of the century“—getting punched in the head by highly trained men is an occupational hazard. The payday can be huge, but the price—in terms of traumatic brain injury—can be very high.
Plenty of sports are hard on the brain. Organized football, from Pop Warner up through the pros, has been rightly pilloried for the devastating toll it takes on players, who suffer from repeated concussions that may lead to chronic traumatic encephalopathy (CTE), the degenerative condition that has claimed so many NFL veterans.
But while football might be the most concussive team sport, it’s followed closely by ice hockey, and then by soccer, lacrosse, basketball, field hockey, gymnastics and baseball, generally in that order, depending on age, gender and the level of professionalism of the players.
Even in football, however, blows to the head are incidental if unavoidable parts of the contest. In boxing, they are the contest—and that means trouble.
“[Boxing] is not really tracked the way school sports are tracked,” says Robert Cantu, clinical professor of neurology and neurosurgery at the Boston University school of medicine. “Concussions in boxing are a poorly reported sample, but at B.U. we’ve had a 100% incidence of CTE in the boxers we’ve studied.”
See the Top 10 Boxing Matches of All Time
Muhammad Ali vs. Joe Frazier, Oct. 1, 1975 As close to death as he'd ever been. And that's how the winner described it. Little wonder that the "Thrilla in Manila" (aka Muhammad Ali vs. Joe Frazier III), tops TIME's list of greatest ever fights. The pair entered the decisive third heavyweight fight at 1-1 and the searing Philippine heat made conditions as close to hell as was possible. From the start there was nothing humane about the way the pair went at each other. You feel that had it not been for the 15-round limit and, ultimately, Frazier's trainer Eddie Futch throwing in the towel at the end of the 14th, they would still be boxing today. "I want him, boss," screamed Frazier. Futch simply replied, "It's all over. No one will forget what you did here today." As for Ali, in typically modest fashion, he described his opponent as, "the greatest fighter of all time, next to me."Rolls Press/Popperfoto/Getty ImagesJack Dempsey vs. Luis Angel Firpo, Sept. 14, 1923 Short and sweet. That's how you'd have to describe heavyweight champ Jack Dempsey's defense of his title against Luis Angel Firpo, the "Wild Bull" of the Pampas, before 80,000 people at the Polo Grounds in New York. Dempsey floored Firpo seven times, with Firpo knocking Dempsey clean out of the ring — and that was just the first round (there was no three knockdown rules back then. Indeed, Dempsey was allowed to stand over the fallen fighter and immediately knock Firpo down again, as there wasn't a rule about going to a neutral corner either). Conspiracy theorists believe that Firpo was denied a valid victory in the first round as Dempsey was helped back into the ring by the writers at ringside and the referee was accused of counting incredibly slowly. Nevertheless, after 11 total knockdowns between the pair, Dempsey won by KO in the second. The fight was also important from a historical perspective because it was the first time that a Latin American boxer would fight for the world heavyweight title.APSugar Ray Leonard, Sept. 16, 1981 This early 80s showdown at Caesars Palace in Las Vegas — billed as "The Showdown" — between WBC welterweight champ "Sugar" Ray Leonard and the hitherto undefeated Thomas "Hitman" Hearns, owner of the WBA crown, was a fight of beauty, full of an ebb and flow throughout. They were fighting to unify the World Welterweight Championship and the stakes couldn't have been higher. First Hearns, then Leonard and then Hearns again held the lead. Between rounds 12 and 13, Leonard's trainer, the legendary Angelo Dundee, exclaimed "You're blowing it, son! You're blowing it!" Leonard simply exploded in the 13th, knocking Hearns through the ropes. He didn't relent and finished him off in the 14th with a furious flurry of punches that forced referee Davey Pearl to call a halt to proceedings. Even worse for Hearns was that he was actually leading on all the judges' scorecards up to that point.Dirck Halstead—Getty ImagesMicky Ward vs. Arturo Gatti, May 18, 2002 This pair put fans through the ringer three times, but their first fight will be seen as their fiercest. Both withstood almost non-stop punishment through 10 rounds of grueling action. Ward, who dropped Gatti in the ninth round with a savage left hook to the body, won the fight by majority decision. That ninth round was called "The Round of the Century" by Emanuel Steward, who co-hosted the fight on HBO. Ring Magazine named the fight the best of the year with boxing fans and writers going one (hyperbolic) step further, hailing it as the fight of the century. Wherever you stood on this, you undeniably wanted more. And fans got it, with Gatti winning two subsequent rematches. Ward announced his retirement before their third fight and will be portrayed by Mark Wahlberg in the film 'The Fighter'. Gatti tragically died in 2009.Steve Miller—APJoe Louis vs. Billy Conn, June 18, 1941 Legendary heavyweight champion Louis took on the Pittsburgh Kid Conn at the Polo Grounds. Giving away at least 25 pounds, Conn was the heavy (or should that be light?) underdog but proceeded to outbox Louis. Boxing historian Bert Sugar wrote that, "Conn could block punches with his arms, elbows and gloves, and further nullify his opponents' punches by 'rolling' with them." By the eighth round, dehydration had set in on Louis and by the 12th he was completely exhausted with Conn ahead on two of the scorecards (Louis later admitted in his autobiography that he rested up toward the end of his training schedule because "I didn't want them to say in the papers that I beat up on some little guy"). Conn got cocky in the 13th and tried to finish Louis off; but by going for the KO, he exposed his impressive defense, was caught by his opponent and was counted out with two seconds left in the round. Let that serve as a lesson to underdogs everywhere.Joseph Costa—New York Daily News Archive/Getty ImagesDiego Corrales vs. Jose Luis Castillo, May 7, 2005 They may not have been household names but with the WBC lightweight title at stake, Diego Corrales and Jose Luis Castillo wowed every house which watched this classic. The pace was simply unrelenting with both fighters landing and receiving repeated blows over nine nasty rounds. The fight ended in memorable fashion in the 10th when Corrales, after being floored twice, rose and landed a devastating series of shots that left Castillo draped helpless on the ropes. But this devastating denouement would not be without controversy: upon getting up for the second time, Corrales spat out his gumshield, thus benefitting from an unofficial 30 second timeout, whereby he literally regained his senses. The pair fought against each other again with Castillo easily gaining revenge. But the decisive final fight, inevitably dubbed "The War to Settle the Score", was canceled due to Castillo weighing too much.Eric Jamison—APMarvin Hagler vs. Thomas Hearns, April 15, 1985 Arguably the greatest opening round in boxing history, the savage pace set by "Marvellous" Marvin and the "Hitman" at Caesars Palace is still discussed to this day. At the time, sportscaster Barry Tompkins, calling the fight for HBO, yelled out "This is still only the first round!" Of course they couldn't keep it up and the aptly named "War" came to a swift end after, in the words of Ring Magazine, the "most electrifying eight minutes ever" as Hagler scored a third-round KO. The enduring image of a blood soaked Hagler being carried around the ring in victory with Hearns being taken back to his corner in a state of semi-consciousness serves to remind us what a brutal sport this can be.APErik Morales vs. Marco Antonio Barrera I, Feb. 19, 2000 Mexicans beam with pride when recalling their countrymen's epic effort back at the turn of the century. Ring Magazine's fight of 2000 was fully justified as the slender boxers belied their small stature to deliver a heavyweight performance which didn't relent (the fifth round has to be seen to be believed) and resulted in Morales winning by a split decision. But considering that Barrera had the only knockdown of the fight, many complained at the outcome which — quelle surprise — led to a rematch (won by Barrera via a unanimous outcome). Cue the third fight (this time at Super Featherweight) where Barrera was declared the winner by a majority decision.Jed Jacobsohn—Getty ImagesJulio Cesar Chavez vs. Meldrick Taylor, March 17, 1990 Endings don't get much more dramatic than this. Expectations were high for the bout nicknamed "Thunder Meets Lightning", referring to Chavez's punching power and Taylor's speed. And while the fight definitely delivered, it enters folklore for the nature of the sudden, dramatic, and controversial ending that continues to be debated to this day. Taylor steadily built a commanding lead on points thanks to easily evading his opponent and outpunching him by a margin of 5-1. But when Chavez did manage to connect, his punches did considerable damage as a result of being the heavier man.
Going into the 12th, Taylor was ahead on all three scorecards (and by a big margin on two of them) but for some reason, Taylor's trainer Lou Duva told his man that he needed to win the final round. Bad move: Taylor was so tired that he fell to the canvas just by failing to land a wild left hand. The final minute was all Chavez and he dropped Taylor with seconds remaining. Taylor got to his feet and was asked by referee Richard Steel if he was able to continue. By not answering (though some say Taylor gave a slight nod), Steele concluded he was unfit to carry on and stopped the fight, scoring a TKO victory for Chavez with only two seconds to go. No wonder his 2009 autobiography was called Two Seconds From Glory.Ken Levine—Getty ImagesChris Eubank vs. Nigel Benn I, Nov. 18, 1990 These two British boxers reached the peak of their careers around the same time. Naturally, fight fans demanded a match-up. The drama kicked in before a single punch had even been thrown: As Eubank walked out to the sound of Tina Turner's "Simply the Best", the song suddenly stopped. It's alleged that Benn's entourage sabotaged the music (to his credit, Eubank was nonplussed and still managed to perform his trademark cocky vault into the ring). Benn, ominously known as the Dark Destroyer, looked furious.
As for the fight itself, it went back and forth as both men gave their all (commentator Jim McDonald screamed at one point, "Jesus, look at that right hand!"). But it was Eubank who took the World Middleweight title when the fight was stopped in the ninth after Benn was subjected to a barrage of blows in the corner despite the fact that he'd floored Eubank earlier that same round. The two fought out a draw a few years later. Despite the build-up, that match couldn't live up to their first meeting which was, indeed, simply the best.Chris Smith—Popperfoto/Getty Images
With good reason. Various studies have put the force delivered by a blow from a trained boxer at anywhere from 450 lbs. (204 kg) to over 1,400 lbs. (635 kg), enough to accelerate the head to 53 g’s. Those forces hit in one of two ways—linear and rotational—and neither of them is good.
“Acceleration from a straight-on punch is linear, while a roundhouse is more rotational,” says Dr. Christopher Giza, professor of pediatric neurology and neurosurgery at UCLA’s Mattel Children’s Hospital, and a former commissioner of the California State Athletic Association. “We think rotational forces are more important in getting knocked out, but most punches have components of both.”
Within the brain, it’s the white matter—or the fatty sheathing on nerve cells that serves as insulation and connective tissue—that suffers the most. “The brain has the consistency of firm Jell-O,” says Giza. “If you shake or twist it you put strain on the connections, leading to stretching or tearing.” That causes both immediate and long-term harm, with the damaged connective tissue leaking what are known as tau proteins, which build up over time to form the signature deposits that signal CTE.
The brain’s slightly loose fit in the skull causes other problems. A thin layer of fluid surrounding the brain is supposed to provides shock absorption in the case of minor blows, but when you get hit hard enough, that little bit of wiggle room allows the brain to rattle around, with soft tissue colliding with unyielding bone. That can cause shock, bruising and even bleeding and death.
In boxing, it’s often easy to see when either kind of damage has caused trauma. The knockout, or the dazed and disoriented condition known as a technical knockout, is practically the very definition of a severe concussion. But most concussive injuries produce subtler symptoms, and while sports like football and hockey are increasingly taking the time to examine players during games and sit them out if there are signs of trouble, that’s not an option in boxing.
“From the ringside, trainers have to examine players very briefly between rounds to determine if they should stop the fight,” says Giza. “They need a very specific set of skills to diagnose a problem so quickly.” With other things going on at the same time—cuts treated, strategy planned—that diagnosis becomes even harder. And since the sport hardly rewards a boxer whose trainer pulls him preemptively, there is a competitive and financial incentive in simply slugging on.
None of this means that all boxers will sustain traumatic brain injury. The 100% figure Cantu cites is derived, he readily acknowledges, from a self-selected population of fighters who come to his clinic seeking help for neurological symptoms. At least some of the larger population of boxers who don’t show up may be fine. What’s more, smart boxers—at least at the championship level—are increasingly taking steps to protect themselves, sparring less, engaging in safe aerobic training more and fighting perhaps only two bouts a year.
But limiting things to two well-compensated fights is a luxury not every boxer can afford. For too many of them—as well as too many athletes in other sports—the payday comes first and health comes second. It’s a way of doing business that growing numbers of athletes live to regret.
