Were it not for World Athletics setting a stack height limit of 40mm for races, many of the best carbon plate running shoes might now look like the Adidas Adizero Prime X Strung, which has a stack height of 49.5mm.
All that foam, plus other tech in the midsole, produces a powerfully propulsive and enjoyable ride for long races, though trade-offs come in the extra weight and instability the high stack creates. I wouldn’t race in it, but if you have no qualms about that stack height then the Prime X Strung is a top option for marathon racing—as long as you escape the heel rub I experienced.
