Nike Free shoes is built as a training tool to help strengthen your foot. That said, Nike made this version more stable by both removing some of the segmentation from the midsole and flaring it for a wider base of support. Thanks to the deep forefoot grooves, our lab tests found the shoe to be the most flexible in this guide. We recommend the Nike Free shoes for runners with normal to flat arches who want to strengthen their feet by doing strides on grass or by walking around the house in a superflexible shoe.