This is a hard question to respond to without knowing a bit of background information first. For example, the answer will largely depend on the number of times the wearer is training each week, as well as the intensity and nature of their workouts.
However, as a ball-park figure, Griffiths estimates most people can expect between one and two years of solid use out of a quality pair of cross training shoes. Although, he adds, “a new color or style will likely take your fancy before you actually need to replace your shoes.”