ULTIMATE FLEXIBILITY TO TRAIN STRONG Designed for high-intensity training, the Nike Free Bionic Women's Training Shoe is our closest-to-barefoot style to date. It features a super-flexible, low-profile fit and a lightweight upper with Flywire technology for excellent stability, support and comfort during cross training, intervals, boot camp and kickboxing. Dynamic Stability The low-profile outsole delivers excellent stability and full range of motion for explosive moves like box jumps, burpees and mountain climbers. Strategically placed overlays at the toe and arch offer added stability during lateral moves and the unique traction pattern under the big toe lets your foot grip the floor for even more stability. Targeted Support Ultralight, wrap-around Flywire threads cradle your foot for exceptional support. The threads are adjustable through the laces and wrap the midfoot and arch, helping to reduce internal slippage during movement. Ventilation The mesh and foam upper helps keep your foot cool and comfortable while providing just the right amount of support where you need it most. Flexibility Outsole flex grooves give you increased flexibility for natural range of motion in any direction. More Benefits Comfort collar and heel conforms to your foot for lightweight comfort and support Cushlon pod under the heel for lightweight cushioning and comfort Molded sockliner conforms to your foot for an anatomical fit, comfort and support Rubber outsole with herringbone pattern for durability and multidirectional traction Nike Free 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.