A mountain porter. Around 25 years ago I hiked up Mt Kinabalu in Malaysian Borneo. It's the highest mountain in SE Asia and the trail is about 8.72 km with and elevation change of 2300m, topping out at over 13k. So roughly the same elevation change as the Barr but in half the distance. There are few switchbacks to speak of, but mostly just up the mountain on a steep, very rocky trail.
I had to hire a guide that would take me up and back in one day. He had climbed up and down that mountain almost every day for many years, and knew the trail like the back of his hand. On the way down it was pouring rain and the trail became a creek. I watched him in amazement tearing down a steep, rocky trail in a heavy rainstorm with a decent sized pack. I have done many trail runs and mountain ultras over the years and I have still yet to see anyone that could match that his downhill running prowess on a technical trail.
I also saw girls that looked about 16 carrying huge wood frame packs of supplies up the trail wearing nothing on their feet but flimsy looking sandals.