My Monday runs are probably the most performant ones of the week. I tend to run much faster and without much stress than Wednesday or Friday runs.

This is probably because I’ve rested over the weekend. One thing that I love is the feeling of breathing unhindered while running almost like the lungs and the breathing are being done automatically and you can just let your body continue managing the breathing process while you concentrate on the muscles and other running stuff like foot and back positioning as well as arm thrusting. And its actually more enjoyable because you can pay attention also to the surroundings but still maintaining a fast pace. Seems to happening frequently on Mondays so perhaps its just a rest-induced thing. Or maybe not.

I read that Tidal volume is the amount of air you suck into your lungs and thus make available to those muscles.

A fairly related is that I also watched a documentary on TV where they said that the Titanosaur Argeninosaurus was the largest Dinosaur in the world and it had the largest Tidal Volume – I don't know what it was but apparently on breathing out if would also breath in oxygen. This was to fuel the large muscles with oxygen they required to heave such a behemoth.