The few socks that have been tested have probably been tested with a static, nonmoving test because it's easier. But a foot is always in motion, so they created a jig that replicates the movement of the lower leg. And they tested it on actual riders to verify the results. This sock can save 2 watts at 50 km h. The newest version has an updated cuff fit for more comfort and aerodynamic gains.
The few socks that have been tested have probably been tested with a static, nonmoving test because it's easier. But a foot is always in