Nike designers worked for approximately sixteen years to create the revolutionary Shox technology. When Nike Shox was unveiled in 2001, three models were available and the Nike Shox R4 was one of these three. It was designed by Bruce Kilgore, of Air Force 1 and Air 180 fame, and Sergio Lozano, the designer of another highly popular and enduring Nike running shoe, the Air Max 95. The principle behind Shox technology is simple. When the heel strikes the ground, the Shox columns absorb the energy of the strike and compress like a spring which bounces back and returns the energy to the wearer as they transfer their weight to the forefoot in preparation for the next stride. Out of all the Shox running shoes, the R4 is one of the most popular and successful with serious runners. The Nike Shox R4 features a two piece, track inspired upper a great, lightweight, breathable fit while the full-length internal Phylon midsole and forefoot Air-Sole unit provide a smooth ride, and this Nike running shoe is designed for the neutral runner in need of maximum cushioning and impact protection.