50k could refer to 50km, yet, ultra usually refers to longer runs like 100km - 50 miles are 80km, so what would make more sense.
Judging by the time per mile they state in the article, it's 50km.
I'm not familiar with the lower layers but found the website above helpful to get an introduction.
50k could refer to 50km, yet, ultra usually refers to longer runs like 100km - 50 miles are 80km, so what would make more sense.
Judging by the time per mile they state in the article, it's 50km.