Two recent, provocative studies hint at why. That Oliver has not broken Robles’s record has nothing to do with an unfortunate stumble out of the blocks or imperfect technique. It has everything to do with biology. In the sports that best measure athleticism — track and field, mostly — athletic performance has peaked. The studies show the steady progress of athletic achievement through the first half of the 20th century, and into the latter half, and always the world-record times fall. Then, suddenly, achievement flatlines. These days, athletes’ best sprints, best jumps, best throws — many of them happened years ago, sometimes a generation ago.

On his blog, Oliver did his best to celebrate; he titled his Monaco post, “I’m sitting on top of the world.” (And why not? The man had, after all, beaten the planet’s best hurdlers for the second-straight week, almost all of whom he’d see at the 2012 Olympics.) But the post grew defensive near the end. He reasoned that his best times should improve.

The next week, he had a meet in Monaco. The press billed it as Oliver’s attempt to smash the world record. But he had a terrible start — “ran the [worst] first couple of hurdles of the season,” as he would later write. Oliver won the race, but with a time of 13.01.

In Paris, for instance, Oliver didn’t talk about how he won the race, or even the men he ran against. He talked instead about how he came out of the blocks, how his hips dipped precariously low after clearing the sixth hurdle, how he planned to remain focused on the season ahead. For him, the time — Robles’s time — was what mattered. He had a blog and called it: “Mission: 12.85: The race for the record.” And on this blog, after Paris, Oliver wrote, “I am in a great groove right now and I can’t really pinpoint what set it off....Whatever groove I’m in, I hope I never come out of it!”

Last summer, David Oliver tried to become one of the fastest men in the world. The American Olympic hurdler had run a time of 12.89 seconds in the 110 meters at a meet in Paris in July. The time was two-100ths of a second off the world record, 12.87, owned by Cuba’s Dayron Robles, a mark as impressive as it was absurd. Most elite hurdlers never break 13 seconds. Heck, Oliver seldom broke 13. He’d spent the majority of his career whittling down times from the 13.3 range. But the summer of 2010 was special. Oliver had become that strange athlete whose performance finally equaled his ambition and who, as a result, competed against many, sure, but was really only going against himself.

Berthelot wanted to know more about the progression of athletic feats over time in these sports, how and why performance improved in the modern Olympic era. So he plotted it out, every world record from 1896 onward. When placed on a L-shaped graph, the record times fell consistently, as if down a gently sloped hill. They fell because of improving nutritional standards, strength and conditioning programs, and the perfection of technique. But once Berthelot’s L-shaped graphs reached the 1980s, something strange happened: Those gently sloping hills leveled into plains. In event after event, record times began to hold.

Except when they don’t. Geoffroy Berthelot began looking at track and field and swimming records in 2007. These were the sports that quantified the otherwise subjective idea of athleticism. There are no teammates in these sports, and improvement is marked scientifically, with a stopwatch or tape measure. In almost every other game, even stat-heavy games, athletic progression can’t be measured, because teammates and opponents temper results. What is achieved on these playing fields, then, doesn’t represent — can’t represent — the totality of achievement: Was Kareem Adbul-Jabbar a better basketball player than Michael Jordan because Abdul-Jabbar scored more career points? Or was Wilt Chamberlain better than them both because he scored 100 in a game? And where does this leave Bill Russell, who won more championships than anybody? By contrast, track and field and swimming are pure, the sporting world’s equivalent of a laboratory.

In the early 1950s, the scientific community thought Roger Bannister’s attempt to break the four-minute mile might result in his death. Many scholars were certain of the limits of human achievement. If Bannister didn’t die, the thinking went, he might lose a limb. Or if no physiological barrier existed, surely a mathematical one did. The idea of one minute for one lap, and four minutes for four, imposed a beautiful, eerie symmetry — besting it seemed like an ugly distortion, and, hence, an impossibility. But Bannister broke the four-minute mark in 1954, and within three years 30 others had done it. Limitations, it seemed, existed only in the mind.

Berthelot speaks with the bemused detachment of a French existentialist. What he predicts for the future of sport is just as indifferent, especially for the people who enjoy it: a great stagnation, reaching every event where singular athleticism is celebrated, for the rest of fans’ lives. And yet reading Berthelot’s work is not grim, not necessarily anyway. It is oddly absorbing. The implicit question that his work poses is larger than track and field, or swimming, or even sport itself. Do we dare to acknowledge our limitations? And what happens once we do?

“We’re reaching our biological limits,” said Geoffroy Berthelot, one of the coauthors of both studies and a research specialist at the Institute for Biomedical Research and Sports Epidemiology in Paris. “We made major performance increases in the last century. And now it is very hard.”

“Bolt is a very particular case,” Berthelot said. Only five track and field world records have been broken since 2008. Bolt holds — or contributed to — three of them: the 100 meters, 200 meters, and 4x100-meter relay. “All the media focus on Usain Bolt because he’s the only one who’s progressing today,” Berthelot said. He may also be the last to progress.

It’s a convincing case Berthelot presents, but for one unaccounted fact: What to do with Usain Bolt? The Jamaican keeps torching 100- and 200-meter times, is seemingly beyond-human in some of his races and at the very least the apotheosis of progression. How do you solve a problem like Usain Bolt?

Berthelot isn’t the only one arguing athletic limitation. Greg Whyte is a former English Olympic pentathlete, now a renowned trainer in the United Kingdom and academic at the University of Wolverhampton, who, in 2005, coauthored a study published in the journal Medicine and Science in Sports and Exercise. The study found that athletes in track and field’s distance events were nearing their physiological limits. When reached by phone recently and asked about the broader scope of Berthelot’s study, Whyte said, “I think Geoffroy’s right on it.” In fact, Whyte had just visited Berthelot in Paris. The two hope to collaborate in the future.

Berthelot argues that performance plateaued for the same reasons it improved over all those decades. Or, put another way, because it improved over all those decades. Records used to stand because some athletes were not well nourished. And then ubiquitous nutritional standards developed, and records fell. Records used to stand because athletes had idiosyncratic forms and techniques. And then through an evolution of experimentation — think high jumper Dick Fosbury and his Fosbury Flop — the best practices were codified and perfected, and now a conformity of form rules sport. Records used to stand because only a minority of athletes lifted weights and conditioned properly. Here, at least, the reasoning is a bit more complicated. Now everybody is ripped, yes, but what strength training also introduced was steroid use. Berthelot doesn’t name names, but he wonders how many of today’s records stand because of pharmacological help, the records broken during an era of primitive testing, before a foundation established the World Anti-Doping Agency in 1999. (This assumes, of course, that WADA catches everything these days. And it probably doesn’t.)

The trend continued through the 1990s, and into the last decade. Today 64 percent of track and field world records have stood since 1993. One world record, the women’s 1,500 meters, hasn’t been broken since 1980. When Berthelot published his study last year in the online journal PLoS One, he made the simple but bold argument that athletic performance had peaked. On the whole, Berthelot said, the pinnacle of athletic achievement was achieved around 1988. We’ve been watching a virtual stasis ever since.

Another Berthelot paper, published in 2008, predicts that the end of almost all athletic improvement will occur around 2027. By that year, if current trends hold — and for Berthelot, there’s little doubt that they will — the “human species’ physiological frontiers will be reached,” he writes. To the extent that world records are still vulnerable by then, they will be improved by no more than 0.05 percent — so marginal that the fans, Berthelot reasons, will likely fail to care.

Maybe the same can be said of the athletes. Berthelot notes how our culture asks them — and in fact elite athletes expect of themselves — to always grow bigger, be stronger, go faster. But what happens when that progression stops? Or, put another way: What happens if it stopped 20 years ago? Why go on? The fame is quadrennial. The money’s not great. (Not for nothing: Usain Bolt said recently he’ll go through another Olympic cycle and then switch to pro football.) The pressure is excruciating, said Dr. Alan Goldberg, a sports psychologist who has worked with Olympic athletes, especially if they’re competing at a level where breaking a record is a possibility.

In a different sport but the same context, another individual performer, Ted Williams, looked back on his career and said, in the book “My Turn at Bat,” “I’m glad it’s over...I wouldn’t go back to being eighteen or nineteen years old knowing what was in store, the sourness and bitterness, knowing how I thought the weight of the damn world was always on my neck, grinding on me. I wouldn’t go back to that for anything.” Remember, this is from a man who succeeded, who, most important, broke records. What happens to the athlete who knows there are no records left to break? What happens when you acknowledge your limitations?

The short answer is, you create what you did not previously have. Swimming records, for instance, followed the same trend as track and field: a stasis beginning roughly in the mid-1980s. But in 2000, the sport innovated its way out of its torpor. The famous full-body LZR suits hit the scene, developed with NASA technologies and polyurethane, promising to reduce swimmers’ drag in the water. World records fell so quickly and so often that they became banal, the aquatic version of Barry Bonds hitting a home run. Since 2000, all but four of swimming’s records have been broken, many of them multiple times.

But in 2009 swimming’s governing body, FINA, banned the full-body LZR suits. FINA did not, however, ban the knee-to-navel suits men had previously worn, or the shoulder-to-knee suits women preferred. These suits were made of textiles or other, woven materials. In other words, FINA acknowledged the need for technological enhancements, even as it banned the LZR suits. As a result, world records still fall. Last month in Dubai, American Ryan Lochte set one in the 400-meter individual medley.

These ancient sports are a lot like the world’s current leading economies: stagnant, and looking for a way to break through. The best in both worlds do so by innovating, improving the available resources, and when that process exhausts itself, creating new ones. However, this process — whether through an increasing reliance on computers, or NASA-designed swimsuits, or steroids that regulators can’t detect — changes the work we once loved, or the sports we once played, or the athletes we once cheered.

It may not always be for the worse, but one thing is certain. When we address our human limits these days, we actually become less human.

Paul Kix is a senior editor at Boston magazine and a contributing writer for ESPN the Magazine.

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