Are carbon-plated super shoes helping runners set records, or is it cheating?

Probably they help: World Athletics concluded that independent research indicates they may give an advantage. Whether that is fair depends on who you ask, and that is the argument. The shoes are thick, springy foam around a carbon-fibre plate. Nike introduced the first in 2016, and the top three men in that year's Olympic marathon all wore it. By late 2023, 15 of the 20 fastest marathon times had been set since 2018.

How much do they help? Nike-funded research says the shoes can improve running efficiency by up to 4.2%, and the size of the gain is still called into question. A New York Times study of race results found everyday runners improving too.

Then the debate begins. Peter Thompson, a coach and former World Athletics official, calls the shoes a "form of mechanical doping" and wants them banned. Others are happy that the sport has new room for innovation after almost half a century without it. In 2020 World Athletics chose a middle way: a 40 mm limit on the sole, one plate only, and shoes must be on sale for four months before they can be raced.

The argument echoes swimming, where full-body suits were banned in 2010. Some commentators suggest that record books should separate the records before and after super shoes.