Cycling shoes act as a second skin on the foot and provide a firm attachment for the lower limbs to the cycle. These requirements leads to a shoes that creates pressure on the dorsal aspect of the foot.
Below is a video where a cycling shoe withour VPECS is tightened when a doppler is placed on the dorsal pedal artery (do not forget to turn the sound on).
This video demonstrates how the pulsations decrease when the shoe is tightened. At the end of the video, the lacing system is opened and the pulsations return.
The second video demonstrates the same shoe but with a VPECS system in place, and here the pulsations remain the same when the shoe is tightened.
The difference in tone and intensity in the two videos depends on how hard the doppler is pressed to the artery and the also the angle between the doppler and the artery.