Don’t Let Your Core Temperature Drop: Change Your Base Layers


I was so close to having the race of my life 2 years ago.  I had made my way up to 2nd place female during a 100 mile trail race and had been able to comfortably hold my position all day and night.  My training had paid off and I was able to execute pacing and fueling according to plan. It was a fluke weather race for the history books with a blizzard and tornado (yes, a tornado in Utah) that hit the day before the race.  The race had to be rerouted for safety and a lot of runners and decided not to even toe the starting line. So here I was at mile 70, climbing strong to one of the highest points in elevation on the course. Despite being wet and cold for the last 24 hours, I had been able to stay relatively dry with the right waterproof jacket, merino wool layers and frequent socks and shoe changes.  Everything was going great until suddenly it wasn’t.

I had made the decision at the previous aid station to hurry in and out without changing my base layer into something dry.  I was feeling pretty warm and had plenty of layers underneath my waterproof coat. Once my pace slowed down toward the top of a long climb, my heart rate dropped along with the temperature.  Suddenly I was shivering uncontrollably. I immediately knew I had made a mistake not to change out my sweaty base layer at the last aid station. Although I had felt pretty good at the time (I had been maintaining a fairly good running pace over some runnably terrain for a few hours heading into this aid station), I knew that my core temperature was likely up from the elevated heart rate due to being able to run.  Once I started the climb and my pace slowed, my heart rate slowed and my core temperature dropped. I didn’t matter how many layers I had on nor that I had a waterproof layer on to keep the snow moisture out. It was my sweat moisture that was making me cold. I was able to make it to the next aid station where I spent two painful hours getting my core temperature back to stable along with changing into a dry base layer.  This allowed me to continue on to a respectable finish time and 7th place female but this was nowhere near the race I could have had if I had made a better decision at mile 65 to change out my base layer. Rest assured I only had to make that mistake once before it will never happen to me again. But now you can learn from my mistake and save yourself from the same fate. When in doubt on a cold race, always take the time to change out your wet base layers.  

Tailwinds,
Coach K