It was a landmark weekend for Kenyan marathon runners.
First, Eliud Kipchoge became the first athlete to mark over the distance, then Brigid Kosgei smashed Paula Radcliffe’s women’s world record.
Both Kipchoge and Kosgei wore bespoke versions of trainers designed to improve running economy by 4%.
It has been reported a group of athletes have complained to the IAAF about the trainers, and the sport’s governing body said this week it had set up a “a working group to consider the issues”.
The idea of modifying equipment to improve performance is obviously nothing new, with the concept of ‘marginal gains’ bringing that into sharper focus.
In this particular case, the Nike Vaporfly has a carbon-fibre plate fitted in its chunky foam sole which supposedly helps propel runners forward.
Dr Thomas Allen – senior lecturer in sports engineering at Manchester Metropolitan University – told BBC Sport: “You can’t radically change a shoe, but reducing the mass of it might give you a 1% gain.
“Adding more cushioning to the midsole might give you another 1% gain. And if you introduce a stiff plate to the midsole, does that give you another 1% gain?
“This technology isn’t new – a university in Canada is considered to be the first to have come up with, and test, the idea of putting a stiff plate in the midsole of a running shoe.
“Nike appear to have gone a step further, as looking at one of the recent patents they seem to have put three stiff plates in the forefoot of the midsole.
“The idea behind those is running efficiency improves.”
