In the world of elite marathon running, Geoffrey Mutai is referred to simply as a “two-oh-three guy.” The title refers to his then (unofficial, due to course technicalities) world record time of 2:03:02 at the 2011 Boston Marathon. A few months after Boston, he shattered the New York City Marathon course record time despite subpar weather conditions. His 2011 race year immediately vaulted him into a legendary echelon alongside his hero and fellow two-oh-three guy, Haile Gebrselassie. “But what do we really know of these exceptional men, except their trade?” journalist Ed Caesar asks in his new book, Two Hours: The Quest to Run the Impossible Marathon. Before Caesar’s quest to understand some of the world’s best athletes, the answer was astonishingly: not much. 

Gebrselassie and Mutai are two of a handful of runners who have made a serious push toward the elusive two-hour marathon. Mutai is the latest in a long line of African runners who have advanced the sport, despite how implausible that may have once seemed. Black Africans were not allowed to compete in official marathon events until the abysmal 1904 Olympic Marathon in St. Louis (the two black South African competitors in St. Louis were there to be showcased in appalling “athletic events for savages” at the World’s Fair). After 1904, many marathons were nothing more than novelty shows, marked by hilarious absurdity. In the past few decades, however, marathons have become big business. A record 50,530 runners completed the New York City Marathon in 2014. Elite runners can make millions from race victories and sponsors such as Adidas and Nike. There’s more incentive than ever to be fast, and the once-impossible feat of two hours is quickly coming into focus. 

To understand the genesis of this evolution, one must first understand that for runners making the greatest strides like Mutai, running is not merely sport, hobby, or competition—it is everything. “When I arrived in Kenya in 2011, I became beguiled by what I saw around me, which was an athletic gold rush,” Caesar says. “Hundreds of thousands of people—men and women—trying to become professional runners. In this one little pocket of the world the way most people think about getting out of poverty is running.” 

Still, some say Kenyans are simply built to run. This incendiary argument of “genetic superiority” is something Caesar examines with a deft, objective, and carefully researched perspective in the book. “We’re not talking about genetically perfect individuals here, we’re talking about traits that may be shared in certain areas in this part of the world that aren’t as present in say, Sweden,” he explains. “Genetics is all fine and well, but essentially what you do with your codes determines what your life is going to be like. With the Kenyans, people talk about genes too much and what they don’t talk about is socioeconomics.” 

Understanding the intricacies of these runners’ lives was essential for Caesar. He took more than 40 international flights tracking Mutai and other elite runners from their training grounds in Kenya to key marathons across the globe. His recounts of Mutai and others on race days as they push for new world records are visceral and physically affecting—it’s almost impossible to read these passages without the heart quickening. 

While Caesar originally planned to feature multiple runners in the book, during his travels something special stood out about Mutai. “Geoffrey thinks about what he does not just in terms of sports. He conjoins the dots between where he comes from and where he is now,” Caesar says. “I went to his camp, which is very, very basic, and far away from anywhere else you’d want to go. There wasn’t any running water then. I asked, ‘Do you mind if I stay?’ and he said, ‘If you don’t mind eating what we eat and doing what we do, then you’re welcome.’ And he immediately gave me his bed—this world-class athlete—and went and slept in a bed with another runner.” 

In September 2014, Mutai’s training partner Dennis Kimetto surpassed his time by running 2:02:57 in Berlin, bringing the record five seconds closer to the two-hour market. The proverbial torch from Gebrlessasie to Mutai was passed once again. Relatively few noticed. On November 1, 2015, more than 50,000 will finish the New York City Marathon again. Few will think they can win, and fewer will care who does. Marathon running is a sport whose boundaries are defined by the limits of individuals on any given day. Will we ever see a two-oh-oh runner? Sooner than later, Caesar thinks. But it’s important not to neglect the road nor the athletes that pave the way. “There’s real magic in what these guys do, and it’s criminal that very few people have taken the time to understand what is going on there,” Caesar laments. “For me, that sense of wonder never went away.” 

Alex Layman is a writer living in Austin, Texas.