I have never met one, but mind you, I haven’t met many runners because I prefer to train alone. What happens when a non-responder actually trains with miles, speed, intervals, strength, etc who run 55 minute 10ks untrained? Do they drop down to 54:30 after 7 years of 60 mile weeks at 10:30 pace or do they stay at 55 no matter what? I’m confused about the concept of being a non-responder. I can believe that people can be shitty responders (drop down from 55 to say 48 with a couple years moderate training) or slow responders (run for years and then break through) but a NON responder? Meaning if you did 6 hours of cardio eveery day you wouldnt see any fitness benefit? Hard to believe.