Nike on Thursday announced the Alphafly 4 as its latest marathon racing shoe. As per the company, the newest addition to the Alphafly lineup focuses on improving energy return, weight, and efficiency over long distances. It features a new Atomknit upper, ZoomX LT foam, updated Air Zoom units, a carbon-fibre Flyplate and a Fast Shot outsole. Nike says the Alphafly 4 is designed for marathon runners, including elite athletes and everyday runners, delivering 10 percent more energy return than its predecessor.