This whole measuring runs by distance only never really made sense to me. Sure, it’s an easy measure and makes for a nice comparison, but it doesn’t really tell you much about a run. Elevation, terrain, temperature, etc all influence the effort required. It’s like tracking your health by only looking at weight – the easy number, but doesn’t give the whole picture.
I haven’t worked out how to account for much of the other things, but mentally I use a nifty little tip my brother once shared. He’s done a LOT of hiking over the years and he had a simple calculation for how far he could walk each day. If he could comfortably walk 20km in a day on flat ground, then in hilly country, every 100m of elevation counted as an extra kilometre. So 400m elevation and 16km was a days walk.
This is easy to transfer to running too – love a good gps watch! A 5km run on the flat if I’m pushing should give me a good, fast time. A 5km run with 100m of elevation, well, that is the equivalent of a 6km effort, so I would expect it to take a fair bit longer.
It can also be comforting when I ran 10km for the first time last year on an almost dead flat route in 1:07, but the best I’ve managed since was 10km with 100m elevation in 1:16. The first one had a pace of 6:43/km, the second a pace of 7:39/km. If I look at the second one as 11km (10km + (100mx10)), it’s actually 6:54/km. Not quite so far off
I guess it’s a quick and dirty version of the “Gradient Adjusted Pace” that Strava does for you. But it’s a nice little mental gimmick to help me account for vastly different times over the same distance in different locations.