Nike Vaporfly and the Super Shoe Rules

Timeline

1. May 6, 2017Eliud Kipchoge wears a Vaporfly prototype in Nike's Breaking2 marathon attempt.
2. 2017The Vaporfly is released to the public.
3. Jan 31, 2020World Athletics sets limits but does not ban the Vaporfly.
4. Apr 30, 2020A rule requires shoes to be on sale for four months before use in competition.
5. Jul 28, 2020With Tokyo postponed, World Athletics adds spike-height limits and a shoe availability scheme.
6. Dec 2021New shoe regulations are approved, effective 2022.
7. Nov 1, 2024A 20mm sole limit applies to track shoes.

The ethical issues

• Technology and the spirit of sport.
• Equal access: athletes sponsored by rival brands.
• Records: comparing eras.
• Commercial influence on rules.
• Regulating innovation without stifling it.

Stakeholders

Stakeholder	Interests & obligations
Elite athletes	Fair competition and sponsorship.
Shoe companies	Innovation and market share.
World Athletics	Integrity and credibility.
Recreational runners	Access to performance benefits.
Record holders	Comparability of achievements.
Fans	Exciting and fair competition.

The case

In 2017, Nike introduced the Vaporfly, a racing shoe with a thick midsole of a lightweight, resilient foam and a full-length carbon-fiber plate.^[1] Kenyan marathoner Eliud Kipchoge wore a version on May 6, 2017, in Nike’s Breaking2 attempt to run a marathon in under two hours, and the shoe was then released to the public.^[1]

Background

The Breaking2 run took place on the Monza motor-racing circuit in Italy. Kipchoge wore a version called the Vaporfly Elite, and the public model was named the Vaporfly 4%, after the claimed efficiency gain.^[1] Nike released a second version, the Vaporfly 4% Flyknit, in 2018. Each later model was designed to be slightly faster and lighter, removing outsole rubber to add more of the ZoomX foam while staying under the height limit.^[1] Sports technologist Bryce Dyer attributed the effect to the combination of foam and carbon plate, which absorbs energy and “springs runners forward.”^[1]

Not everyone thought the shoes were a problem. A former World Athletics official and coach told the Wall Street Journal that athletes would wear them because they gave an advantage without hurting them.^[1]

The rules and governance

World Athletics regulates equipment through its technical rules, and the 2020 change defined limits that could be checked objectively. Soles could be no thicker than 40mm. A shoe could contain no more than one rigid plate or blade, which could be in more than one part but had to lie in a single plane, not stacked or overlapping.^[1] The four-month retail rule targeted access as much as performance: any shoe had to be available to any athlete on the open market, in shops or online, before it could be used in competition.^[1][2]

The rules affected manufacturers’ business decisions. Brooks said that it would normally spend more time between prototype and market, but that the ruling made it reassess its strategy, and other companies were in the same position.^[1] The 2021 regulations gave a long lead time for the 20mm limit on track and field shoes, partly to reduce the burden on manufacturers.^[3]

The performances

The key laboratory evidence came from a 2018 study in Sports Medicine, funded by Nike according to its grant listing. Eighteen high-caliber runners ran repeated five-minute trials at 14, 16 and 18 km/h in a prototype shoe and in two established marathon racing shoes, with shoe mass matched. The prototype “reduced the energetic cost of running in all 18 subjects tested,” by 4.16% and 4.01% against the two comparison shoes. The authors predicted that “top athletes could run substantially faster and achieve the first sub-2-hour marathon.”^[5] Runners wearing Vaporflys and their successors won major marathons and set records, and a Wall Street Journal analysis found Nike-sponsored athletes in the shoes held the top marathon times.^[1] Critics called it “technological doping.” One former official described it as a “form of mechanical doping” and argued it should be banned to “protect the integrity of the sport.”^[1] Others compared it to the full-body swimsuits that were banned after the 2008 Olympics.^[1]

World Athletics’ rules already said shoes “must not be constructed so as to give athletes any unfair assistance or advantage.”^[1]

The 2020 rules

On January 31, 2020, World Athletics announced new rules, but did not ban the Vaporfly.^[2][4] An internal review group found “independent research that indicates that the new technology incorporated in the soles of road and spiked shoes may provide a performance advantage” and “sufficient evidence to raise concerns that the integrity of the sport might be threatened.”^[2]

The rules limited soles to 40mm and allowed only one rigid embedded plate.^[1] From April 30, 2020, any shoe had to be available for purchase on the open market for four months before it could be used in competition; prototypes were banned.^[2] Shoes customized for aesthetic or medical reasons were allowed, provided they otherwise complied.^[2] Any shoe that failed the new plate and sole requirements was placed under an “indefinite moratorium” with immediate effect. Referees could demand an athlete’s shoes for inspection after a race, and World Athletics could bar a shoe while studying it.^[2] The rules came from an Assistance Review Group of technical, scientific and legal experts and athlete representatives. It recommended further research and a new working group of biomechanics specialists, to which shoe manufacturers would be invited.^[2] President Sebastian Coe said: “As we enter the Olympic year, we don’t believe we can rule out shoes that have been generally available for a considerable period of time, but we can draw a line by prohibiting the use of shoes that go further than what is currently on the market while we investigate further.”^[2] He framed the limits of the governing body’s role: “It is not our job to regulate the entire sports shoe market but it is our duty to preserve the integrity of elite competition.”^[2]

Competitors rushed to bring their own designs to market so their athletes could use them at the Tokyo Olympics.^[1]

When the Games were postponed, World Athletics revised the rules again on July 28, 2020. Road shoes stayed at 40mm. New limits for spiked shoes aimed to “maintain the current technology status quo” until after Tokyo.^[6] It also created an “Athletic Shoe Availability Scheme,” under which manufacturers of newly approved shoes committed to making them available to unsponsored elite athletes, free or for purchase. Its stated aim was to have them available one month before international competitions.^[6] Chief executive Jon Ridgeon said the rules reflected “the existing shoe market in these challenging economic times” and “a broad consensus with the shoe manufacturers who are major investors in our sport.”^[6]

Aftermath

In December 2021, World Athletics approved new regulations, in force from January 1, 2022.^[3] They limited the rules to “applicable competitions,” so they would not apply to amateur club, school, college or masters events. They shifted enforcement toward post-race spot checks by a new shoe control officer. They also banned embedded “sensing or intelligent” technology.^[3] Ridgeon said the aim was to support innovation while ensuring it “does not create unfairness or a paradigm shift in athletic performances.”^[3] It considered limiting energy return but did not adopt one, citing the variables involved and the impact on manufacturers.^[3] It set a 20mm sole limit for all track and field shoes from November 1, 2024, giving manufacturers notice.^[3]

The core dilemma

Sport has always embraced better equipment. But when a shoe measurably improves performance, and only some athletes initially have access, results may reflect sponsorship rather than ability. Where should the line be drawn, and when?

Competing values

• Innovation vs. fairness.
• Athlete performance vs. comparability of records.
• Commercial freedom vs. equal access.
• Regulatory caution vs. decisive action.

Strongest arguments

For permitting super shoes: innovation is part of sport, the shoes are commercially available, and they may reduce injury and fatigue.

For stricter limits: the gains are large enough to distort results and records, and early access depended on sponsorship.

Applying the frameworks

Justice

A justice lens asks whether athletes compete on equal terms when their results depend on which company sponsors them. The four-month availability rule and the ban on prototypes aim to give all athletes access to the same technology, but sponsorship contracts still limit which shoes many can wear.

Utilitarian

Consequentialists weigh faster times, excitement and possible injury reduction against unfairness, the devaluing of historic records, and higher costs for athletes. Drawing lines at a measurable stack height lets innovation continue while limiting the largest effects.

Kantian (duty)

A Kantian lens asks what the sport’s rules are meant to test. If running is meant to measure human effort and skill, technology that substantially changes performance must be regulated so that the rule applies equally to everyone. Using unpublicized prototypes would treat rivals unfairly.

Walk it through: the Simple Decision Model

1. Spot the issue. You are a World Athletics technical official in late 2019, months before the Tokyo Olympics, as shoes with thick foam and carbon plates dominate results. The stakeholders include athletes, manufacturers, sponsors, fans, record holders and national federations. The code in play is the rule that shoes must not give unfair assistance or advantage.
2. Gather facts. What does independent research show? How widely available are the shoes? What enforcement tools do you have?
3. Test options. Options: (a) ban the shoes; (b) allow them but cap height and plates and ban prototypes; (c) take no action pending more research. Weigh fairness and the integrity of records against innovation and athletes’ preparation for the Games.
4. Check codes and law. Are commercial relationships influencing your judgment? Would your rule be clear and enforceable for all manufacturers?
5. Decide and document. Record the evidence and the reasons for the limits.
6. Communicate and follow up. Communicate the rules clearly with enough notice, and commit to further research and review.

What’s settled and what’s contested

• Settled: the 2020 and 2021 rules; the 20mm track limit.
• Contested: the size of the advantage; whether records should be treated differently.

Why this case matters

The Vaporfly case is a key example of how governing bodies regulate technology that changes performance.

Key terms

Equalizer vs. enhancer

Whether a technology or adaptation restores a level field (adaptation) or gives an advantage beyond it (augmentation).

Rules vs. spirit of the game

Rules are the written minimum; the spirit is the fairness and respect the rules exist to protect. Rules set the floor; spirit sets the ceiling.

Commercialization

The process of turning sport into a product and a business enterprise, with profit pressures that can compete with principle.

Distributive justice

Fairness in how scarce opportunities, resources, benefits and burdens are shared.

Definitions from the Ethics Cases glossary.

Discussion questions

1. Is a shoe that improves efficiency different in principle from better training or nutrition?
2. Was World Athletics right not to ban the Vaporfly in 2020?
3. Should records set in super shoes be treated differently?
4. How should regulators handle athletes contracted to brands without equivalent technology?
5. Who should set the line between innovation and unfair advantage?

Sources

1. Nike Vaporfly and Tokyo 2020 Olympics controversy — Wikipedia
2. World Athletics modifies rules governing competition shoes for elite athletes — World Athletics
3. New athletic shoe regulations approved by Council — World Athletics
4. Nike Vaporfly Shoes Avoid Olympics Ban — The New York Times
5. A Comparison of the Energetic Cost of Running in Marathon Racing Shoes (Hoogkamer, Kipp, Frank, Farina, Luo & Kram), Sports Medicine 48 (2018) — Sports Medicine (Springer), via DOI
6. World Athletics amends rules governing shoe technology and Olympic qualification system (July 28, 2020) — World Athletics