Free your run. A more flexible midsole with a barefoot-like feel. Nike Free 3.0, 4.0 and 5.0 are designed for ultimate flexibility for a more natural ride. The breathable engineered mesh upper features strategically placed overlays and a reflective midfoot underlay support panel for comfort and support. After viewing athletes training barefoot in 2002, Nike set out to develop an athletic shoe that would feel more natural and weightless, simulating barefoot running. They began to study a group of male and female athletes by taping pressure-measuring insoles to their feet and using high-speed cameras to capture images of each of their feet in motion.