Karl was a mountain bike racer and working as a mountain guide on Kilimanjaro when his friends, noticing he was very fit, suggested he go for Kilian Jornet's FKT.  He asked,

"Who is that?  What is an FKT?"

Karl went up and back very fast - while wearing a bike jersey - and a new career was launched. That winter he prepared for Aconcagua, and heard Kilian was going also, who then set a new FKT.  When Karl heard the time, he thought,

"Oh no! I need to become a better runner. I quit biking, and trained hard, because the up and back it's almost 40 miles."

Karl is unmatched at altitude - and he has good stories!