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The fall is almost here and I can not wait! Frankly, I am just tired of running in heat and humidity. Granted, today wasn’t as bad as last Saturday and thankfully it was cloudy.  However, when I come home and weigh my clothes after a run and the scale says 2.5 pounds, I know it’s been a rough run. In addition, I think the chafing is causing permanent scaring.

This week was the easy week of my training schedule. I haven’t really put an emphasis on speed, just getting in the miles. Today’s run was scheduled to be a little more difficult- run 15 miles but race 13.1. Racing is always easier when entered into an actual race, but I decided I had the mental capability to grind it out for 13 miles. As you can see from my stats here, that didn’t work out so well. My goal was to run those 13 miles between 7:10 and 7:15 per mile. I started out okay but after 4 miles at this pace or a little faster, I decided to reevaluate my plan. Instead, slow down and take one mile at a time. If you need a slower mile, take it. And that’s how it went for the remainder of the run.

I still managed to finish in a decent time and I was really stoked with my last mile split – 7:20 on tired legs (thanks to Eminem and a burst of energy.) But the thought kept crossing my mind that maybe I’m not going to be in shape for the 3:20 (hilly) marathon I’m hoping for in November. Then I reminded myself, this humidity is clearly affecting my performance. But exactly how big of a factor is it?

Apparently there is no magical forumla to determine how much you will slow down per mile based on humidity. Everybody is different and we all handle heat and humidity differently. But basically humidity slows down the rate of sweat evaporation, hence preventing the body from cooling off as efficiently. The more moisture in the air, the less your sweat is going to evaporate. And then your clothes soak up the moisture and your running with an extra 2 pounds of sweatiness. 🙂

This chart from the NOAA shows what the temperature REALLY feel likes based on % humidity and actual temperature:


This morning the humidity started out at 93% and 72 degrees. Eventually the humidity went down, but the temperature went up. There is a great article over at iRunFar that explains how exactly runners can acclimate to heat. It’s a little lengthy but I found the comparisons between elite marathon performances in different years and different weather conditions quite interesting. The last sentence gives me hope for my race:

So, in my experience, heat acclimation based on well documented scientific principles can give athletes a significant performance enhancement in hot environments.

After this summer, I think I’ll consider myself pretty well heat acclimated. As I’m typing this, a cold front has just moved in to NC and there’s an aguacero outside. But hello to 60 degrees! It’s clear nobody is going to have their optimal race in humid conditions but I’m keeping my fingers crossed for a cool, dry November 4th.

Happy Running and Happy Trails,


2 Comments Post a comment
  1. Emily Wilson #

    I can most definitely attest to the effect humidity has on performance. I did the VA Beach Rock ‘n Roll Half Marathon last weekend and, being from the glorious NC mountains, I immediately felt my disadvantage. I just decided when I walked out of the hotel that morning at 5:30 am and immediately started sweating that my time was going to suffer. But I had a great time, I can highly recommend the Rock ‘n Roll series, they put on a great event. It’s already fall up here in Boone and the leaves are starting to turn. I’m always sad to see summer end, but fall is a great time for running in the mountains. Thanks for posting, I really enjoy reading them!

    September 8, 2012
  2. It’s just started with Summer here (2 months late) and just in time for my half marathon next week! Hope it cools down!

    September 9, 2012

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