New rules outlaw some of Nike's record-breaking shoes

World Athletics announced significant changes to its rules on Friday that will outlaw some variants of Nike's Vaporfly running shoes and introduce strict limits to the technology developed for any future shoes used in elite competition.

The sport's governing body (WA) said that with immediate effect, road shoes must have soles no thicker than 40mm and not contain more than one rigid, embedded plate.

The Vaporfly shoes used by Eliud Kipchoge to run the first sub-2 hour marathon and by fellow Kenyan Brigid Kosgei to smash the women's marathon world record both contained triple carbon plates inside thick, ultra-compressed foam, said by Nike to help improve running economy by up to four percent.

The new rules also state that, from April 30, any shoe used in competition must have been generally available to the public for four months - putting paid to the use by Nike and others of prototypes by its athletes in major races.

There will also be new rules governing the construction of track spikes.

WA's review concluded that the new technology "may provide a performance advantage and could raise concerns that it might threaten the integrity of the sport".

WA will now establish an expert working group to guide future research into shoe technology and to assess new shoes that emerge on the market.

Nike did not immediately respond to Reuters' request for comment on the decision.