These Nike Alphfly NEXT% trainers, designed by the Nike Sport Research Lab in Portland, Oregon, are designed to optimise an athlete's energy return. A prototype was worn by Eliud Kipchoge in a record-breaking under two hour marathon.

The Nike Sport Research Lab is recognised for working with athletes and designers to create trainers to enhance performance in a variety of events. The Lab was established in 1980 with the goal to study runners in order to design sportswear that optimally suited their needs. Today, employing around 40 researchers, the Lab draws on expertise in biomechanics, biomedical engineering, and kinesiology to drive innovative developments across the Nike brand.

Focused on long-distance running, the Alphafly trainers are an iterative development of Nike's Zoom Vaporfly 4% shoes, introduced in 2017. The aim with Alphafly was to make adjustments to the shoe to improve the efficiency of the runner's movements. From assessments of runners, the team determined that the runners needed further support in the forefoot of the shoe, which resulted in a number of material and technical innovations to create the Alphafly, which were released to the consumer marker in the summer of 2020.

Whereas the Vaporfly model reportedly increases a runner's efficiency by 4% (hence the infusion of the percentage in the name), the Alphafly model is claimed to improve running economy between 5 and 8%. Thicker ZoomX foam, Zoom Air Pods, and a revolutionary carbon fibre plate all contribute to the Alphafly's significant improvements in running economy. The plate provides stability and stiffness, but also 'rocks' forward, helping propel the wearer into their next step from the front of their foot.

In October 2019, elite athlete Eliud Kipchoge broke the record for the fastest marathon while wearing a prototype of the Alphafly trainers. As a result of the shoe innovation and careful race management, Kipchoge was enabled to run the first under two-hour marathon. These same race-management measures mean that Kipchoge's race time of 1:59:40 does not officially count as a world record. While the shoes are recognised as a factor, the Kenyan Wold and Olympic champion's marathon time is a hugely-significant sporting achievement. When asked about the controversy over the Alphafly model, Kipchoge stated 'We live in the 21st century and we need to accept change/ Development goes hand-in-hand with technology. The shoe is good. [...] We should accept technology and marry technology'.

Following Kipchoge's marathon, the international governing body World Athletics announced its first-ever shoe ban, disqualifying any shoes with a sole thicker than 40mm or with more than one carbon fibre plate in elite competitions. Shoes must also be available to the consumer market to purchase at least four months before being allowed in competitions.