I ran a 10k in Thailand this month and ended up crashing during the second half of the race. It was hot and humid, and I thought I had acclimatized to the heat and humidity with over one year of living and training in the Southeast Asian heat and humidity. Before acclimatizing to intense humidity of dew points over 70 F, I could not run over one mile without having to stop for water and briefly cool down, but afterwards I could run longer without having to stop.
I realized that I just can't race 10k's if the dew point is over 70 degrees.
At 6'1" and 150 pounds, my height makes it difficult for me to compete in intense humidity compared to shorter people who are 5'7" or under.
Conditions
Temperature: 82 degrees
Humidity: 70%
Dew point: 71 degrees
Wind: None. Stagnant tropical air.
Sunlight: None
Time: Evening
The race
5k into the race, I was at around 20 minutes and felt fine.
I wanted to do negative splits and run the 10k under 40 minutes.
Just past the 5k, my system totally crashed. I started breathing really hard, then I felt like this intense was creeping out of my body, causing what felt like an intense fever.
I ran the 2nd half of the 10k in 30 minutes. It wasn't because of my legs, lungs, heart, or feet. It was that I felt completely overheated and ready to explode. It was basically a heat tolerance exercise at that point, and I could only jog it while breathing really hard.
Went over to the water station and had to stop because my head felt like it was going to explode from the heat. Luckily they had water bottles, so I grabbed one of those and constantly splashed my head with water every 2-3 minutes. Even then I felt excruciatingly hot.
Finally, I finished, but my time was about 50 minutes.
Some Thais actually raced really well in the humidity. I noticed that they were mostly 5'7" or shorter, with the shorter guys (5'3"-5'5") being some of the fastest ones. The average male height in Thailand is 5'7", so I'm 8 inches taller than the average Thai man. Maybe that's what killed me in the race.
Unfortunately, 5k races in Thailand are mostly untimed fun runs, while 10k races are considered to be the "real" ones. But while I can do 5k's in the humidity, I realized that I just can't run 10k's in the humidity because my system would just shut down after a certain point. I had trained for a year in high dew points but could never complete long runs without stopping for water breaks.
Even in the coolest parts of Thailand in the north, the dew point rarely gets below 70 F except for during the short cool, dry season, when dew points are often in the 60's and minimum temperatures are in the 60's and rarely in the upper 50's; during 8-9 months of the year, temperatures never drop below 72 degrees. This is why Southeast Asia is hell for runners. At least in Texas and the Deep South, you get nice, cold breaks from such weather during the winter.
And comparatively, a dew of point of 71 degrees that night wasn't too bad, because in the central and southern parts of the country, dew points would regularly be in the 75-78 degree range. At least I'm in the north where dew points are usually in the 70-75 degree range. I would like to be able to race a 10k well in these conditions, but I guess my tall body just isn't built for it.
How does everyone else here deal with racing longer distances in intense humidity where the dew point is 70 degrees or over?