I've only done one 2k session. It was on Thursday. I started the sub 40 program on Tuesday.
Today I did the 1h 30min long run. I started at incline 3%. It felt much tougher than when I usually run at that pace outside. My HR went very high too, so I decreased the incline first to 2%, but then to 1%.
That felt more like the usual effort at above 5:00 pace.
My HR still went pretty high. Above 160 at least half the exercise.
It might be explained by the very high temperature in the gym today and the abscence of A/C - I don't know
I really feel that the treadmill is a lot of trouble when it comes to knowing what's authentic or not. I really don't want to do any mistakes by running with too little effort or too high effort. That might spoil everything - right?
What do you think of it all?
Anyway, Here's the data from today
PS. If you wonder about the strange splits sometimes around 1 hour it's because of the treadmill - it can just go for an hour at a time
PS2. Here's my data from the 10k races earlier this year if you're curious.