I recently got back from my first trail race at altitude and have a new respect for those real trail race folks. I’ve seen the various threads on here where road runners and trail runners snipe back and forth about which is harder/more impressive, but never really had a frame of reference. I live a few hundred feet above sea level with no real tough trails nearby and the hilliest race I had previously ran was Boston.
After having finished a trail half marathon that gained 1500 feet (up to close to 10,000 ft total altitude) in about 2 miles and lost that much in even fewer miles. The surfaces varied from packed dirt, rocks, a few small creeks and loose dirt/leaves. It was just as hard for me doing 10/11 minute miles through that terrain as doing 6:30 minute miles during a road half marathon. But it is a completely different type of hard.
There shouldn’t be any real comparison between trail and road racing because they requires such different skillsets. Obviously you need great endurance and an impressive VO2 max for both but that is about where the similarities end. Now when I see the times for elite trail runners doing a tough course at altitude, I can better appreciate the unique talent they have.