2001 - A team of Nike designers visits Stanford University’s track and field practice, where the coach has the team running drills—barefoot. He believed that best strengthened the runners’ feet and Tobie Hatfield, nike free  Director of Athlete Innovations and Explorations, has his lightbulb moment

2002 - The sport research lab uses pressure mapping and motion capture to analyse the toes, knees, ankles and hips as athletes run barefoot on grass- the results become the key info designers use to create early production samples of the first nike free run 2 (which, when tested against a traditional running shoe, showed increased balance and greater flexibility in the feet and ankles).

2004 - The first generation nike free 5.0 V4 hits the market. The unique sole is halfway between natural flexibility of running barefoot and the support of a traditional running shoe.