Romano,
You're cool. Hope CP didn't take offense at the baristorial convolutions; I actually never took the calculus (although I read some commentaries on it by Leibniz when I was studying philosophy — after quiting biochem). I spent my time in probability, statistics, sociometrics, and multiple regressions — did read the theoretical math journals in the library at college once in awhile when I was playing hookey from my job in the library offices on summer breaks. But CP and you reawakened it all, and CP is good at it.
I think the minor shifts on the graph can be major in reality at the upper end — two miles or ten miles is a big distance when I am approaching the end of a trek, especially if the terrain is going to be bad like walking through volcanic cinder for a mile in order to get to my car.
Most of all the graphs are, IMO, a confirmation of training, fitness, experience, gear quality, lightitude, etc. If I could get a performance graph like that I would kiss the beautiful earth next to my car door at the end … on my way to get a burger and fries after a longish trek (or long for me).

