The focus has moved beyond the feet to the most injury-prone part of a runner's body. The knees. The Adrenaline GTS 21 GuideRails keep you moving comfortably through the gait cycle by keeping excess movement in check. The stability is balanced with BioMoGo DNA and DNA LOFT cushioning that work together to provide a just-right softness underfoot without losing responsiveness and durability. The Engineered mesh and the 3D Fit Print upper provide the structure and proven fit.