[Someone]

Factor 3 (7 km/hour) is very fast walking for ‘normal’ people.

Speed walkers can go over twice as fast, but they don’t really walk.

https://www.iaaf.org/responsive/download/downloaddirect?file... defines it as

”Race Walking is a progression of steps so taken that the walker makes contact with the ground, so that no visible (to the human eye) loss of contact occurs. The advancing leg must be straightened (i.e. not bent at the knee) from the moment of first contact with the ground until the vertical upright position.”

and also states:

”All the Judges shall act in an individual capacity and their judgements shall be based on observations made by the human eye.”

Of note here is the “to the human eye” phrase. If one were to introduce electronic aids similar to those used in fencing to detect whether there always is a foot on the ground, speeds would decrease significantly.