Tierney ran her debut 'thon at the Twin Cities Marathon in the fall of 2018. This was just weeks before the Minnesota state XC meet in early November. I saw Tierney before the start of the Class A race, and wished her good luck. She gave me her trademark bright smile. As the race took off, it was the race that everyone expected, with Tierney and Grace Ping running neck-to-neck out front. (Lauren Ping was right behind them.) They disappeared around a corner, but the announcer kept the crowd informed that the two of them were exchanging the lead. They blew the first mile in a very fast time for the St. Olaf course. Then as the race came back into view, Grace and Lauren were running 1-2, which is how they went on to finish. Tierney was DNF, following a spill on a downhill.
A week later, at Nike Heartland, the two of them were once again glued to each other. In this video, Tierney is running in bib 3222, with Grace glued to her hip (that's Emily Covert out in front):
https://www.youtube.com/watch?v=TodowdL7HfQ
At the finish, it was Emily Covert, Grace Ping, and Lauren Ping, in that order. Tierney was again DNF.
Whether she was hindered by the aftereffects of that first marathon, I don't know. But it's great to see her running healthy and strong now.