Ah ha you chose to select TDS as an example?! I was in that race too. It was nearly 98-miles with 28,000' of climbing this year and we had to go through extended stretches of 3" of snow and mud....in the night and in fog/rain. It is also a way more technical trail compared to say a UTMB.
I can assure you (I finished in 22 hours) that there was certainly a lot of "powerhiking" as many of the trail grades exceed 15%-20% and it was slippery and technical. After about 50km/30-miles it is generally not very runanble on those types of climbs (keep in mind your pack of required gear weighs over 4lbs) and probably 95% of the field is using trekking poles. I probably wasted 5 + minutes alone having to stop and put on/take off my rain pants and mess around with my second headlamp during the race.
The first mile was run in around 6:40 for me and I was buried in maybe 40th place then. After that you are climbing up a ski resort out of Courmayeur and things get a bit steep.
For sure I was walking out of aid stations nearly every time (helps to digest food) and if you look at my total elapsed time vs actual moving time you can see at some aid stations I was spending nearly 10-minutes (Had to drink some soup with noodles in it and get a mandatory gear check!). So with "moving time" I think I averaged about 12:50/mile pace.
This is actually a pretty "extreme" 100-mile mountain race example though because of the weather this year and the technical nature of these steep mountain trails.
Details on Strava here:
This whole thread is an entertaining exercise of semantics. Would I say I "ran" TDS? Yes!Did I in fact have to walk/powerhike a lot of the climbs? For sure!
Even some of those downhills (think 600 foot drop) are on pretty technical trails in slippery conditions and a 9-min mile actually feels like you are flying when you are 55 miles deep into this kind of race.
Most ultras in the US aren't like this at all though....maybe only Hardrock.