With zero-drop shoes, the foot sits flat on a level surface ... it still looks like it’s dropping two millimeters from heel to forefoot,’ and I’m like ‘let’s get that extra two millimete ...

If someone runs in a higher-drop shoe (even 6mm up to 12mm), there might be some initial calf or Achilles soreness a day or two after running in zero-drop shoes.” Another use case for zero-drop ...

Zero-drop shoes can make it easier to run with ... The first shoe has 3mm of rubber between the foot and the ground, while the latter two shoes have 10mm of semi-firm foam from heel to toe.

A 4mm drop would seem undetectable—the height is approximately two stacked nickels—but as a runner who’s had her share of wipeouts from time to time in zero-drop shoes, that 4mm was appreciated.