By now, probably just about everyone has seen amazing footage of single- or double-amputee runners, using Össur's Flex-Run carbon fiber running blades. The springy substitutes for legs allow their users to run so fast and naturally, that there is currently a debate over whether or not it would be fair to allow athletes using them to compete against non-amputees. Carbon fiber isn't exactly known for its grippy qualities, however, so Nike has been working with one-legged triathlete Sarah Reinertsen, to create the equivalent of a shoe that could be used with the blades. The result is the Nike Sole.

Like many blade users, Reinertsen started out using the sole from a regular running shoe, which she just cobbled onto her prosthesis. In 2006, however, she began collaborating with Nike's Innovation Director Tobie Hatfield, on a purpose-built sole. This month, they revealed the finished product.

The Nike Sole consists of an outsole and midsole, along with a layer of thermal plastic urethane called Aeroply, which is made of recycled Air Bag units (these provide cushioning in the soles of some Nike runners). This layer serves as the interface between the sole and the blade.

Nine nylon tabs wrap around the edges of the blade to hold the sole in place, while a stretchable rubber leash with a tactile grip pulls up over a medallion on the blade, to keep the sole from sliding off.

The Nike Sole-equipped Flex-Run can reportedly now be purchased through prosthetists' offices around the world. There's no word on price.

More information is available in the video below.

Source: Össur via Designboom