Nike Free, created by Tobie Hatfield and Eric Avar back in 2004, has continuously evolved over the years. The Nike Free RN 2018 PS 'Gym Blue' perfectly exemplifies these updates, showcasing the notable changes made to the adult shoe. Noteworthy enhancements include a Dynamic Fit inner sleeve and a flexible back heel strap that securely holds the foot while still allowing for unrestricted movement. Furthermore, the shoe boasts a rounded heel that smoothly rolls with the ground, promoting a more natural stride. Additionally, incorporating spandex into the circular-knit upper and laces adds to the overall flexibility, enabling a greater range of motion.