Appeals to self ignorance (huh?), self-authority (I'm a physician), ridicule (that is so convoluted), et tu-ism (that's bro science too), etc
Why don't the idiots just shut up and learn something? Gas exchange is highest when the pH difference between blood and muscle is high, i.e. when intramuscular pH is low and blood pH is not. This is due to differences in the affinity of oxygen and carbon dioxide for hemoglobin at different pH levels.
You hit that sweet spot only after a working anaerobically for long enough to get intramuscular pH that low. Until then, you can't be near working hard "aerobically" because the gas exchange rate is chemically limited. Long enough is more than 20 seconds for everyone, full stop.
Don't make me explain this again, particularly if you consider yourself educated, because it is true. Go find a source that contradicts it if you feel like wasting everyone's time some more and being slow forever. Ignorant ingrates.