Before heading out on your run, be sure to check the air quality index and the heat index. If the air quality index is code orange and you’re sensitive to air pollution and/or have upper respiratory problems you may not want to run. If it’s a code red, it’s not suitable for anyone to run.
The Heat Index tells you what the temperature feels likes when combining the air temperature and the relative humidity. For example, if the air temperature is 90° and the relative humidity is 70%, then it’s going to feel as if it’s 106°! Ouch! Not good running conditions!
12-16 oz. 60 min before run
16-20 oz. every hour of running in hot conditions
12-16 oz. in cooler less humid conditions
<60 min.. water ok
After 60 minutes (and sometimes sooner if it’s really hot and you sweat a lot) you begin to deplete vital electrolytes (i.e., sodium, potassium, etc.). Sodium is needed in order for your body to absorb the fluids your ingesting.
After your run, you need to replace the water you’ve lost. A good way to check this is to weigh before your run and then weigh after your run. Drink 16oz of water for every pound of water lost. After you do the weigh-in a few times you’ll get a feel for how much rehydration you need depending on how much you sweated and you probably won’t need to actually weigh yourself.
Most of all, listen to your body and don’t try to defeat Mother Nature. Mother Nature is undefeated.