Watch the Epic Quest to Run a Marathon in Less Than 2 Hours

See how hard work and scientific innovation almost helped this man make history.

Twenty-five seconds—that’s how tantalizingly close Eliud Kipchoge came to a world first.

Kipchoge's attempt at history is explored in the recently released documentary Breaking2, produced by National Geographic in partnership with Nike, which is available above.

Kipchoge, largely considered one of the world’s best marathon runners, had been attempting to run a marathon in under two hours. For months, the elusive "sub-two-hour" marathon loomed over him as he underwent extensive training.

His test came on May 6 when he arrived at the Monza Formula 1 racetrack near Milan, Italy. Kipchoge and two other runners, Lelisa Desisa and Zersenay Tadese, hit the pavement with two hours on the clock. The event was staged by Nike; it showcased everything the brand wants their athletes to be and everything they promise their customers they can become—the best.

And if anyone was going to create history, it would be these three. Desisa has won the Boston Marathon twice, and Tadese holds the world record for the half-marathon.

In addition to their athletic prowess, the runners had a powerful network of scientists and engineers behind them—who worked on the best training schedules, fitness regimens, and running shoes available, all sponsored by Nike. Studies have shown that everything from how a runner lands on the ball of his or her foot to the length of a runner’s stride can influence the final time across the finish line. Elite runners often develop an efficient stride. This, combined with the rate with which they take in oxygen and how easily their muscles fatigue can determine their endurance.

While experts debate the importance of genetics in athletic success, others, like Nike, are looking at how technological innovations in products like running shoes can give runners a leg up. (Read more about the scientific quest to break the two-hour marathon barrier.)

It should be noted that Kipchoge did achieve a record on May 6. The previous world record for running a marathon belonged to Dennis Kimetto, who ran the 2014 Berlin Marathon in 2:02:57. Kipchoge beat that by more than two minutes after he ran a marathon in 2:00:25.