World Athletics Council ban Nike Alpha Fly trainers worn in sub-two-hour marathon
The international body that governs track and field has announced it has "amended its rules" on what shoes athletes can wear in competitions.
The changes made by World Athletics Council mean the Nike next-generation Alpha Fly trainer will be banned - the shoe Eliud Kipchoge ran a sub-two-hour marathon in Vienna in October 2019.
As a part of the amended rules, shoes must have been available on the open retail market for at least four months before they can be used in competition.
On their website, Nike says Kipchoge "tested" a number of "prototype" trainers in competitions suggesting the shoes were not available on the wider market.
Nike has been approached for comment.
The World Athletics Council says it hopes the changes will provide "greater clarity" to elite runners. In a statement it said an Assistance Review Group had concluded:
"There is independent research that indicates that the new technology incorporated in the soles of road and spiked shoes may provide a performance advantage".
The sporting body said it would therefore be carrying out "further research" to "establish the true impact" of new technology used in running shoes.
The review comes off the back of a study by the New York Times last year which suggested runners using Nike Vaporflys could be at an advantage in races.
But Kipchoge told the Telegraph he feels the focus on the Nike trainers is wrong.
"They are fair," he said. "I trained hard. Technology is growing and we can't deny it - we must go with technology."
Commenting on the body's findings, World Athletics President Sebastian Coe said: "It is not our job to regulate the entire sports shoe market.
"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."
What are the amended rules set out by World Athletics
The group says there will be "an indefinite moratorium" on any shoe that does not meet the following requirements:
The sole must be no thicker than 40mm.
The shoe must not contain more than one rigid embedded plate or blade (of any material) that runs either the full length or only part of the length of the shoe. The plate may be in more than one part but those parts must be located sequentially in one plane (not stacked or in parallel) and must not overlap.
For a shoe with spikes, an additional plate (to the plate mentioned above) or other mechanism is permitted, but only for the purpose of attaching the spikes to the sole, and the sole must be no thicker than 30mm.
In addition from 30 April 2020, any shoe must have been available for purchase by any athlete on the open retail market (online or in store) for a period of four months before it can be used in competition.