In an announcement much of the running world has been anxiously awaiting, World Athletics, the governing body for competitive track and field, ruled today that it will not ban Nike’s high-tech Vaporfly shoes. That means Nike athletes will be able to wear the elite Vaporfly versions at the Summer Olympics in Tokyo and any records set wearing the shoe will be recognized as legitimate.

The ruling comes with a caveat, though. World Athletics wants to restrict technological developments in footwear design to level the playing field and the regulations now allow the thickness of a shoe’s sole with a limit of 40 millimeters. That is greater than the current Vaporly shoes, which have a 36-millimeter sole. It would also limit shoes to a single rigid embedded plate, like the current Vaporflys.

 The portion of the ruling that will most interest run specialty retailers is a requirement that beginning on April 30 any shoe used in elite competition must have been available for purchase on the open retail market for four months. That means competing prototypes from other footwear brands will not be allowed in elite races if they aren’t available in stores by the end of April.

 Bottom line, it means that Nike’s shoe can be worn by runners in the Olympics, but attempts to match the technology by rival shoe manufacturers won’t be allowed unless they reach the retail markets by early April.

 “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,” explained World Athletics president Sebastian Coe, adding that World Athletics, formerly the IAAF, reserves the right to tighten the rules in the future if it sees an undue influence in the high-tech shoes.