Enjoy running in the Mach 5 for tempo/competition with a caveat, well two caveats but one is obvious. The obvious issue is the rubberized EVA sole which will wear faster than rubber limiting its life. The other, less obvious issue is the midsole foam is so soft that upon running downhill for moderate or up weighted runners, causes the foam to bottom out. You notice a definite squish and then thunk where it hits bottom. Lighter runners may not notice it. Overall great for flat tempo days or fast track days though with snug upper, good energy rolling forward and light weight.