Whenever I run hills it just feels lot harder and more tiring than running with a sled. I’m inclined to believe that what “feels” harder and gets you more tired isn’t necessarily more effective than something that feels easier.
It may be easier to keep all hill questions under one thread…
Here’s some actual data (with one source missing):
It appears generally that for the first 10 meters at least that hills work better than sleds and heavy works better than light. But sleds are more controllable (it’s easier to put 5% of BW on a sled than on a hill) and 0-10m is different than 10-40m. You can have a steeper vs shallower hill gradient (I actually have that) but it’s usually easier to modulate stimulus with a sled.