Notes on heat acclimation

I did receive a response from Karl King. Here is what I asked him;

1 - What references/studies do you have on heat acclimation, and what is the
best way to get acclimated?
2 - Is high dew point/humid heat acclimation different?
3 - How long does one need to get acclimated?
4 - Can someone like me truly acclimate, or do I just accept that I will never run decent races in that kind of weather?

Here is his response;

Do not take excess S Caps. Hydration is from water, not S Caps. It is extremely rare that one needs more than 2 per hour, but there are exceptions. Probably only 1% of the population needs more than 2 per hour. I know of only one person who requires 4-6 hour.

The best way to heat acclimate is to run in the heat consistently for 10-14 days. Dew point is not an issue. I have a bad record of runs in hot, humid conditions, so I was very concerned when I signed up for the Vermont 100. I ran in the hottest time of the day, and over dressed slightly for those runs. Whenever I drove anywhere, I rolled up the windows on the car and suffered in the heat. It was not unusual for the temps to be in the range of 105 to 110F. I did that for a couple months before the race. By the time I got to Vermont, I had tremendous heat acclimation. I needed all of it. On race day the temps and the humidity were over 90. Only 48% of the field finished, and I was one of them.

My heat acclimation lasted into October, and then finally I lost it.

So, you can heat acclimate for hot, humid conditions. You just have to spend a lot of time in those conditions before race day.

If you take more S Caps than you need for the conditions, you will get very thirsty and drink lots of water. That will be bad for performance, slowing you down from the useless weight. It is better to be slightly on the low side than to take too many. I go by my stomach. When it starts to feel a little off, I take an S Cap, and that usually does the trick for the next hour or so.

I guess I already knew some of this, but I did not realize the power of constant exposure to heat. I remember not having an issue with it in college, and remember that I also did not have air conditioning.

I found a lot of stuff on heat acclimation, and the consensus seems to be 2 weeks of daily training/exposure to heat of at least 1 hour per day. What I did not realize was how quickly it goes away. If there is a week of cool weather, one can loose a significant amount of the acclimation.

I actually found a guide for Army Rangers who are about to go into training. This is designed to have them acclimated when they arrive. Kind of interesting stuff.

Conclusions:
1 - Heat acclimation takes 2 weeks.
2 - Air conditioning can detract from your acclimation
3 - 1 - 2 hours per day of exercise is needed in the heat for the acclimation.
4 - It goes away quickly

I guess I intuitively knew this, but I learned a few things.

So, if I am going to run Afton, I have 2 1/2 weeks of riding around in my car with the heat on.