pEliud Kipchoge has cemented his status as one of the most successful distance runners of all time.ppThe decorated 32-year-old Kenyan marathoner has nabbed seven first-place finishes in eight career marathons, flashing across finish lines with sub-five-minute splits. His personal best is a lightning-fast 2:03:05.pp[RELATED1]ppAnd yet Kipchoge doesn't exude any of the hubris so common to today's McGregors and Ronaldos. Instead, the self-made millionaire with the megawatt smile exhibits a monklike zen and an unshakable positivity. He approaches the sport with a lionhearted pride, which is exactly how he trains.ppKipchoge's motions are lithe, almost feline, as he runs among his training group. Every move of his 5'6" frame, from arm pump to footstrike, is calculated and exacting. He's about as perfectly built for marathons as a human can be, making him a "unique problem" for sports scientists when he and two other runners—Zersenay Tadese, 35, and Lelisa Desisa, 27—attempted Nike's lofty, moonshot goal of breaking a two-hour marathon.pppbr br br br br Mark McCambridgeNike br br br br pIf you watched (or kept up with) the monumental Breaking2 attempt in Monza, Italy, you know that Kipchoge missed 1:59:59 but clocked the fastest (unofficial) time in history with 2:00:25. National Geographic partnered with Nike to narrate Kipchoge's journey. Here's what it took to shave 2.5 minutes from his time, what went into optimizing the "perfect marathon" conditions, and how scientists went about tackling the biggest challenge of all: improving a practically flawless runner.pFinding Kipchoge's "Achilles' heel"pFirst, it's important to understand why Kipchoge is so talented: He has an above-average exercise capacity, an exceptional VO2 maxa, and a high lactate threshold, meaning his body more easily transfers oxygen into energy.pp[RELATED2]ppSo Breaking2's lead physiologist Brett Kirby, Ph.D., focused on the two elements of Kipchoge's game that he could obviously control: nutrition and gear.pp"Eliud had the opportunity to improve how he managed energy levels during the marathon," Kirby, a Nike Sport researcher, tells Men's Fitness. "Two strategies we used to make this happen were 1) personalizing Eliud’s Vaporfly Elite shoes, enabling him to maintain race pace at a lower required oxygen cost, and 2) adjusting the carbohydrate amount in Eliud’s drink during both training and racing so he could preserve stored muscle energy levels for longer durations."pppbr br br br br Mark McCambridgeNike br br br br pGroundbreaking? Not exactly. Nike didn't set out to drastically change Kipchoge (or any of the runners') diet, regimen, or form—mostly because they didn't have to.pWhat Kipchoge eats to fuel monster mileagepb"bEliud eats a staple Kenyan diet full of Kenyan greens, ugali, and lots of Kenyan tea," Kirby says. Ugali is a polenta-like dish made from cornmeal, sorghum, or millet flour. "In the days leading up to the race, including the morning of the race, Eliud consumed carbohydrate- and nitrate-rich foods, and during the race he consumed a drink mix consisting of both carbohydrates and electrolytesa."pp[RELATED3]ppKipchoge's perfected his game-day nutrition to include foods that rev his engine but avoid stomach discomforta. Keeping him well-hydrateda was the bigger goal. In fact, all the runners had different hydration beverages and frequencies tailored to their bodies—some bottles had higher amounts of sugar (or a different type of sugar) and some with added caffeine, according to a Nike press releasea.pKipchoge's Breaking2 training planpKipchoge's regimen was varied and gradually grew more grueling leading up to race day.pp"Preseason, Eliud did gym aerobics for one month," Kirby says.