Nike’s 2017, $250 Zoom Vapor Fly running shoes claimed to improve a runner by 4% compared to their previous model. New Balance’s FuelCell 5280 priced at $200 also claimed to greatly enhance a runner’s abilities. How? Both these shoes use a carbon plate that has unidirectional fibers. This allows the shoe to flex in any direction but still maintain its shape. These carbon fiber plates are acting as a lever, rather than just a spring, to give controlled motion forward.