An unpleasant topic, sweat. But one that is so dominant on outside runs this time of year that it deserves its own posting.
Here's how bad it's gotten here: Today it is 92 degrees with humidity at 47 percent. Not too bad on the TH Index, but the Index is smart. Once it gets above about 87 degrees one should not be running anyway, so the Index is not important. 92 is above 87, so don't run. But what if I run at 84 degrees and 76 percent humidity?
The first mile is not too bad. It can actually feel good for the first couple minutes. But then a general heating feeling comes over my body, and the sweat starts quickly on the brow and chest. After a mile the arms are covered, after two miles the back is sweating and the shirt is showing sweat on the front, after three miles the shorts are feeling wet and the shirt is wet and wiping the brow is not keeping the sweat from the eyes.
Four miles in and things are coming apart: the hair on the arms and legs is getting matted by sweat, the hands are dripping from the sweat running down the arms, the sweat rag is soaked and ineffective in defending the eyes from the sweat, the head hair is getting matted, and the body is struggling to keep blood going to the muscles since most is heading for the skin surface for cooling.
Five miles and speed begins declining as the physical toll is becoming real. All the issues in mile four get more serious, and it's around this point that the leg hair is matted in moisture like post-shower. Thirst sets in as the general sweat flies from the hands and drips quickly and steadily from the chin. Eyes are burning and there's nothing to do about it.
Six miles and it's getting close to time to shut down for the day. Enough fluids have been lost, and the body knows it even if the mind doesn't by slowing down more and sweating at the same full-body outrageous rate. Or at least you better hope you are still sweating. If not, be prepared to meet your maker.
There should be no further running. Six is enough in these conditions. Maybe more early in the morning when the temperature is lower and the humidity is higher, or at night with relatively higher temperatures but lower humidity, but it's just hot.
And maybe dangerous. Be careful.