The Nike Free TR Twist GLM: Premium fit, lightweight flexibility Designed with a reflective coated mesh upper and durable leather overlays, the Nike Free TR Twist GLM Women's Training Shoe delivers breathability, minimal bulk and high visibility. For natural range of motion, this performance shoe is built with Nike Free flex grooves for a feel similar to bare feet. Benefits Reflective coated mesh upper with leather overlays for a lightweight, breathable fit and visibility in low light Full length Phylite midsole provides lightweight cushioning Rubber pods on the heel and forefoot provide durability and multidirectional traction Multidirectional Nike Free flex grooves allow for barefoot-like flexibility Origins After learning that Stanford athletes had been training barefoot on the university's golf course, three of Nike's most innovative and creative employees set out to develop a shoe that felt natural and weightless, similar to bare feet. In 2002, they examined a group of men and women with pressure-measuring insoles taped to their feet, using high-speed cameras to capture images of each foot in motion. The team spent eight years studying the biomechanics of shoeless running. The results yielded a profound understanding of the foot's natural landing angle, pressure and toe position, allowing Nike designers to build an unconventional and flexible running shoe from the inside out.