THE SECRET BEHIND SUPERSHOE SPEED

ONE WEEK BEFORE the 2018 New York City Marathon, Olympian Jared Ward received a package from Saucony, his shoe sponsor. Inside were three early prototypes of what eventually became Saucony's first super shoe, the Endorphin Pro 1.

- SCOTT DOUGLAS

Ward's typical marathon race-week workout is four one-mile repeats at marathon pace. He decided to convert the session into an experiment, with the help of Iain Hunter, an exercise science professor at Brigham Young University.

Ward ran the workout on a treadmill while Hunter measured his running economy, which is how much oxygen is needed to run at a given speed. Improve your running economy, and you can either hold a given pace for longer or you can cover a set distance faster at the same effort level.

Ward ran each mile repeat in a different pair of shoes-the three prototypes, plus a Kinvara, Saucony's lightweight trainer that Ward was planning to wear at New York. "As soon as I finished the fourth interval, I pulled off the mask and said, 'Doc, that's the one,'" Ward says. Hunter's numbers backed Ward's intuition: His running economy in the first two prototypes was essentially the same as in the Kinvara, but in the third prototype, it was 4.4 percent better. After just five minutes of running in it, Ward decided to wear the third prototype at New York.

"There were times in the race I thought about the shoes," he says, "but it was all very positive. It felt easier, it felt more efficient, so in my mind, the shoes were working." Despite being injured coming into the race, Ward placed sixth in 2:12:24, his best race in more than two years since he placed sixth in the 2016 Olympic Marathon.

Ward's holy-smokes experience was common in the early days of super shoes. Also common was the belief that the carbon-fiber plates in super shoes acted as springs that led to being faster in the shoes.

That explanation was soon found wanting.