Meb Keflezighi nears victory at the Boston Marathon in April. PHOTOGRAPH BY STEVEN SENNE/AP

An élite marathon is a competition, but it is also a collaboration. For much of the race, the runners work together, drafting behind each other as they move through the streets as a pack. Eventually someone breaks away, but that usually doesn’t happen until the last quarter of the race. Those who try earlier tend to get swallowed up by the main pack, and are never heard from in the race again.

“It’s very, very, very, very difficult to lead point to point in a marathon,” Meb Keflezighi said recently over the phone from Mammoth Lakes, California, where he was concluding his preparation for this year’s New York City Marathon, which will take place on Sunday. “Ninety-nine per cent of the people that do point-to-point leading in any marathon usually they get caught, because the drafting of a group of people will eventually hunt you down.”

But occasionally the gamble pays off, as it did for Keflezighi this past spring, in the Boston Marathon. After about seven miles of the 26.2-mile race, he broke away from the lead pack. By the time Keflezighi entered the Newton hills, around mile sixteen, he led the pack by nearly a minute and a half, though that didn’t last. At mile twenty-four, Wilson Chebet, of Kenya, had closed to within eight seconds. But Keflezighi hung on to win by eleven seconds, in a personal-best time of 2:08:37.

Running Boston alone from the front had never been Keflezighi’s intention. But around mile five, he saw three Ethiopian runners go to the head of the lead pack and slow down the pace. “My goal was to win, to get on the podium, or run a personal best. And, if I’m going to do that, I’m going to contribute to the pace and push it hard, and may the best man win,” Keflezighi said. “I made a move and I said, 'Come with me if you’re going to come.' And this is what happened. That’s what racing is. … You have to assess the situation.”

The rest of the field does, too. An early move like Keflezighi’s forces the runners in the pack to make a decision: Do I go with him or do I sit back and risk losing contact, trusting that we will reel him in later? Despite Keflezighi’s silver medal at the 2004 Olympics, his victory at the 2009 New York City Marathon, and his fourth-place finish at the 2012 Olympics, fifteen other runners in Boston—including the defending champion, Lelisa Desisa, of Ethiopia, and Kenya’s Dennis Kimetto, who set the marathon world record last month, in Berlin—had personal-best times faster than his.

“The reason I think they let me go was because my last marathon was horrible,” Keflezighi said. “They said, ‘He’s no good. He’s going to come back to us.’ ”

They also likely thought about the advantages gained by staying with the main pack, like protection from the wind provided by the runners in front. There’s also “a psychic edge,” Michael Joyner, a physiologist at the Mayo Clinic, said. “People get in a rhythm. You’re feeding off other people. All of the signals that the average person would describe as painful, the élite is using as a red line. They’re running right on the edge. When you’re with somebody else, your perception of the effort you require, your perception of fatigue, might be less. You might be able to stay in the zone longer.”

More often than not, the runner who attempts to break away will run out of energy. At last year’s New York City Marathon, the Ethiopian Bronx resident Buzunesh Deba entered with the hope of breaking the course record of 2:22:31. After the first two miles, Deba and her training partner at the time, Tigist Tufa, took off from the lead group. By the halfway point, the pair led by more than three minutes. Shortly after mile eighteen, Deba had lost Tufa and was on her own. “It was difficult to lead from the beginning,” Deba said from Albuquerque, where she was in training for this year’s New York race. “It was really windy. That’s why Jeptoo”—Priscah Jeptoo, of Kenya—“stayed behind. After eighteen miles, she came after me by herself, and she had full power.”

Deba didn’t. In Central Park, around mile twenty-four, Jeptoo caught Deba, and went on to win by nearly a minute, in 2:25:07. Deba held on for second.

While Deba fared far better than most who attempt this strategy, the approach is still widely considered a marathon misstep—some instances more obvious than others. At the 2011 New York City Marathon, the favorite, Mary Keitany, of Kenya, set out at world-record pace on what is arguably the most difficult course of any of the world’s major marathons. The move seemed brazen. The women’s world record, 2:15:25, set by Paula Radcliffe in 2003, is considered almost untouchable. But, if anyone is going to break it, Keitany, who is the second-fastest female marathoner ever, has the best chance. Yet even she knew she wasn’t capable of it that day in New York.

“My plan was completely different, but I made a big mistake,” she wrote in an e-mail. “I didn’t set my G.P.S. in miles.” The day before the marathon, Keitany and her trainer had worked out her splits based on a pace of 3:21 per kilometre. A few kilometres into the race, however, her G.P.S. lost its connection, forcing Keitany to rely on the mile clock. She tried to mentally convert the splits into kilometres, but got confused and, instead, she says, “had to follow my feeling.”

In a marathon, where the first half often feels run at the tempo of a tortoise, this can be dangerous. A marathon requires patience and restraint. “When I started to realize my mistake, it was too late to do any other action than try to run alone till the end, hoping that the [two-minute] gap I accumulated in the first half was enough to win the race,” she said.

It wasn’t. Keitany slowed from running just over five-minute miles at the start to running six-minute miles near the end, pedestrian by every élite standard, and shocking to see from one of the greatest distance runners of her generation. Yet her lead was so great that the eventual winner, Firehiwot Dado, of Ethiopia, and Deba didn’t catch her until mile twenty-five. Keitany hung on gamely until almost the very end, when the pair finally pulled ahead. Keitany finished third.

Despite their experience with front-running, or perhaps because of it, it is unlikely that Keflezighi, Deba, or Keitany will try to break away from the pack early in this year’s New York City Marathon. Speaking for herself, Keitany admitted as much: “I will not start too fast, like I did in 2011.” She’s been training with a G.P.S. set to miles ever since.