So I think I'm figuring a few things out. This morning I go out and run 3 miles at a pretty good clip (7:30 pace). It is really hot, humid and the dew point is 72. By the end of the 3 miles I am sweating up a storm. Sweat is flinging off of me like crazy. I can tell my body temperature has risen. At this point I decide to slow down but the heat has already done it's damage.
I ran almost the same run the other day with a dew point of 68 and didn't really sweat for the first mile and then was able to keep up a good pace for the entire 6+ miles. Today I had to really slow down after 3 and by the end of the 6.8 I was walk/jogging.
My theory is:
The dew point, when that high, doesn't allow the sweat to evaporate off of my body (obvious). In turn my body temperature rises, then at some point my heart says "that's enough" and my HR lowers causing the lactate buildup. My hands start to swell up (side effect) because of the low blood flow and I'm done with productive running.
That's my theory and I'm sticking to it. I need some lower dew point days!
By the sweat of your brow
you will eat your food
until you return to the ground,
since from it you were taken;
for dust you are
and to dust you will return.”