Earlier quoted context omitted.
I'm afraid you may be missing the point. The evidence you give (dog runs faster than you) doesn't really mean anything, and exercise does not affect anatomy. These are vets giving expert opinions and you are a (former) pug owner with an anecdote.
Ok I will take the bait - breathing, especially over the course of lets say ~45 minute run should definitely have some relation to the part of anatomy the article was talking about (specifically, the vets are claiming that the smashed nose shape makes it harder for them to breath, in relation to other dog breeds). Surely being able to breathe correctly is necessary to run for 45-50 minutes continuously? What I am cla…
That you had a single individual that you believe did not suffer from the issues related to extreme brachycephaly doesn't really tell us much.
The problems are only partly related to inbreeding - selecting for dogs with such squashed heads is bad in and of itself.