When It Comes to Running Shoes, How Fast Is Too Fast?

Molly Woodford, MJLST Staffer

On October 12, 2019, Eliud Kipchoge made headlines for running a marathon in 1:59:41 in Vienna. A day later, Brigid Kosgei broke Paula Radcliffe’s long-standing women’s marathon world record by over a minute, recording a time of 2:14:04 at the Chicago Marathon. Nike sponsors both athletes. Kipchoge’s run does not count as an official world record for a number of reasons, including a rotating phalanx of pacemakers and a pace car, but he holds the official world record of 2:01:39 set at the Berlin Marathon in 2018. Two weeks before Kipchoge’s historic sub-two-hour run, Kenenisa Bekele, the world record holder at 5000m and 10,000m, missed Kipchoge’s world record by a mere two seconds at the 2019 Berlin Marathon. Nike also sponsors Bekele. All of these record-setting athletes wore some version of the Nike VaporFly during their races.

This spate of record-setting performances has reinvigorated a debate in the running community about whether these shoes confer an unfair advantage to competitors who wear them and should, therefore, be banned. The first iteration of the Nike VaporFly, later dubbed the 4%, first appeared on the feet of elite athletes in early 2016, at the U.S. Olympic Marathon Trials. The shoe became available to the public in July 2017, retailing at $250. Several studies (1, 2) have shown that, true to its name, the Nike VaporFly 4% makes wearers approximately 4% more efficient compared to other racing shoes (which make the wearers ~1.9% faster). Nike has since released an updated version, the Next%, which was worn by Kosgei in Chicago and Bekele in Berlin, as well as by Kipchoge’s entire rotating phalanx of pacers in his sub-2 attempt. Next%, now also available to the public for $250, is certainly intended to, and based on recent performances may actually, confer a benefit of more than 4% to its wearers. But is that fair? Other companies are racing to compete, but none appear to have caught up to Nike just yet. And, whether or not it is fair, is it legal?

In April 2017, the IAAF significantly modified its rule regarding shoes, apparently due to “speculation and the increased interest in the development” of the 4% and other shoes. Before the rule change, “[a]ll types of competition shoes [had to] be approved by IAAF.” After the change IAAF appears to approve the shoes post hoc, and only “[w]here evidence is provided to the IAAF that a type of shoe being used in competition does not comply with the Rules or the spirit of them” at which point “it may refer the shoe for study and if there is non-compliance may prohibit such shoes from being used in competition.” In response to the advantage conferred by the Nike VaporFly, IAAF released a statement in mid-October stating that its technical committee had established a working group to look into the issue.

Even if IAAF eventually determines that Nike’s technological advances are too advantageous, Nike seems to be the main beneficiary, thus far, of IAAF’s rule change. Nike has received an enormous amount of free press, this blog included, because of the recent spate of record-breaking performances, and the surrounding controversy. However, a group that could benefit are up-and-coming, innovative, shoe manufacturers. In the late aughts, a company called Spira built a marketing campaign around being banned by USATF and IAAF because of springs in their shoes. Whether or not Spira was ever actually banned appears to be an open question—USATF repeatedly stated that Spira was not banned, and three runners wore Spira shoes in the 2008 Olympics. However, Spira filed a lawsuit against USATF and IAAF, alleging that the organizations had violated antitrust laws. Spira voluntarily dismissed the suit. Although there is other evidence that USATF believed that Spira did not comply with the IAAF shoe rules.

Spira still exists today, though they never took off as a serious running shoe brand. Whether the Spira controversy was completely authentic or drummed up for publicity, the next Spira could benefit from IAAF’s rule change. Instead of worrying about when and if they’ll receive IAAF approval, a new company and its shoe will only be scrutinized by IAAF if “evidence is provided to the IAAF that a type of shoe being used in competition does not comply with the Rules or the spirit of them.”