While these speedsters could easily pass the test on race day, they double as your go-to shoe for your training routine. The supportive fit and soft cushioning work together to make them comfortable enough to withstand those double-digit mileage days, and light enough to help quicken your tempo when the time is right. Nike ZoomX foam in the footbed delivers energy return, while a visible Zoom Air unit provides responsive cushioning-giving you an additional spring with your stride. Nike React technology is a lightweight, durable foam that delivers a smooth, responsive ride. Using data from hundreds of runners, traction is placed where your foot needs the most grip on multiple surfaces. A translucent Flyknit upper provides breathability in areas where your foot heats up most. It uses strong, stretchy yarns to create a lightweight yet supportive feel with every mile.