W NIKE FLEX TRAINNike Flex Train Women's Workout Shoes Lift. Sprint. Move. In the Nike Flex Train, you have the freedom to choose your own workout adventure. With a flexible outsole and lightweight upper, it unlocks a wealth of training options. Flexibility: Very High Rubber outsole with built in cutouts and thin slits in the forefoot provides flexibility. Stability: Moderate Elastic band around the heel adds support. Cushioning: Moderate Full length foam midsole