The Nike Shox shoes were the product of a sixteen years of research in the Nike Labs. In the fall of 2000, the Nike Shox system was revealed to the world. Nike unveiled this top secret line of shoes to the world in 3 models, the Nike Shox R4 (running shox), Nike Shox BB4 (basketball shox), and the Nike Shox XTR (cross-training shox). How did the system work? It was actually very simple - the Shox would absorbs energy from impact (kinetic energy) of the wearer’s heel and then returns the stored energy (potential energy) as he moves forward. The Nike Shox technology does a better job of returning the energy transfered to it than the Air Max shoes. The Shox shoes were very cutting edge using a super high density polyurithane hollow foam columns as the shock absorbers in combination with a TPU heel counter to ensure equal distribution of the energy from impact. The Nike Shox R4 running shoe has been the most successful shoe in the Nike Shox lineup. The shoe was available in a variety of colors and was also available on Nike ID. The R4 has been released several times and is the only shoe in the original lineup to have been released several times.