Running a brutal 171km and climbing a dizzying 10,000 metres on a course passing through France, Italy and Switzerland, athletes can take over 46 hours to finish. 

Katie, who (as always) finished with a smile, claimed 6th place with a time of 27h22m56s. 

Katie's partner and fellow On athlete Germain was also in high spirits as he finished.

In a moment that highlights the sense of camaraderie and community often associated with trail running, he crossed the line arm in arm with fellow joint-ninth place finisher Javier Dominguez Ledo. 

Both finishing after a grueling 23h16m03s. 

Widely regarded as the most important and most demanding trail event in the world, UTMB sees tens of thousands of trail enthusiasts descend on Chamonix in France to be part of the festivities.

"The start of the race was absolutely crazy! There were people everywhere, hanging out of hotel windows, lining the streets… all there to support us in our crazy decision to run 100 miles around Mont Blanc," said Katie. 

"After the first 5-10 minutes of the race, my face hurt from smiling so much! When the night finally set in I found myself not feeling so great and losing motivation. But I kept seeing familiar faces and hearing people cheering my name and I was able to hang in there.

"Then I met up with another female runner at an aid station and spending some time running and chatting with her really brought me back to why I was out there in the first place - to share an adventure with so many great people.

"I’m really proud to have finished my first UTMB and my first 100 mile race without any major issues, and show myself that I’m strong enough to stick it out through some tough lows and make it to the finish line.

"Getting news of Germain looking strong and moving up in the field was a huge relief and gave me a little extra energy to keep moving, I was so happy and proud of him! I’m so grateful for all the people who came out to support us, from our crews at aid stations to friends who hiked in just to give a cheer and a hug.

"We’re so lucky to have such an amazing community of support around us! Now we’re looking forward to getting back the Parc National du Mercantour for some fun, slower paced days in the mountains this fall."

"The race went well for me, I felt surprisingly great the entire time. I tried to manage a sustainable pace and not take any big risks since my main goal of the day was to see the finish line for my longest run ever," said Germain.

"I’m really happy I was able to share almost 80km with a new Spanish friend Javier and cross the line together. We worked hard to push each other and overtake a few people throughout the day, so sharing a finish with him was even better than arriving in Chamonix alone.

"Already looking forward to next year and seeing what I’m able to do with a little more risk-taking. Now time to go back to the quiet of our home mountains and wait for snow."

Another On athlete David Hauss was also competing at the UTMB, in the 101km CCC event. He did well to complete the course but was not happy with his 40th place overall.

“Not the race, nor the result I was expecting for this (race),” he said, afterwards. 

“I wanted to go ahead but quickly realized that I lacked the strength and energy (on the day). It wasn’t a great day even if there were positive signs before the race but that’s the sport.

“Thank you for all your messages and congratulations to all the racers.”