How is this even possible?
The best runner in my town runs his easy days at marathon pace (around 3:30–3:35 per km) every single day. Even his long runs, 20 or 25 km, are at that pace! And on top of that, he still does fast intervals like everyone else.He usually gets injured once a year, in the summer, but still manages to hold 120 km per week at that pace for the whole season. It’s incredible.
Has he just become extremely efficient at that speed? He says that running at 4:20/km feels too slow for him, so he just goes with what feels fast but comfortable.