Wednesday, July 8, 2009


Why Does It Feel So Hot?
Our environment effects the way our body feels in different climates. When our body gets hotter we perspire. The evaporation of our perspiration is what allows our body to cool itself. When the humidity is higher less perspiration can evaporate at at time, so we feel hotter.

Heat Index
When exercising outdoors, you need to pay attention to not only the temperature but the heat index. The ideal heat index for any work out is actually 65 degrees. As it gets warmer, you will need to take in more water. Exercising in temperatures over 90 degrees can be dangerous. Here is a website with a good Heat Index Calculator. The NOAA Heat Index

Heat Stress
The longer you work out in high temperatures, the more stress you put on your body. Make sure to acclimatize to warmer weather. Gradually increase your work outs. Do not to high stress activities. No intervals, sprints, or hard runs. Be aware of your sleep! Sleep deprivation has been a common factor in running related heat deaths in the last few years. At any point, if you feel really hot, and your energy is tanking, stop! Don't push it.

How Much Water?
The common suggestions of the past were "Drink A Lot and Drink Often." Then a study was done on Marathon runners and they found a common heat related injury was drinking too much water. So they asked the elite runners how much they drank and the rule of thumb was "If they were thirsty they drank." Hmm makes sense to me, but how much is enough.

My Formula
I can't actually take credit for this. I have read this in several running magazines and on the web. I weigh myself before I run. I take tons of water with me when I run. As I get hot and thirsty I drink. Some times I feel like I drink every few seconds, some times it is every few minutes, but when it is hot I drink. I never do anything longer than 45 minutes in hot weather. I normally go for only 30. Then when I am done, I weigh myself again. Normally I weigh less. They weight loss is water loss. So lets say I weighed 180 (I wish). Lets say the temperature was 85 degrees. I drank 1.5 liters of water in 30 minutes, and when I got back I weighed 179 lbs. 1 liter of water weighs 2.2 pounds. So I drank about 3.3 lbs of water and lost 2 more sweating. So I drink on more liter. That means that at 85 degrees I lost 2.5 liters of water in 30 minutes. As it gets cooler, I will loose less water and as it gets warmer I will loose more. That gives me a guide as to how much water I will need. I do this for every run in temperatures above 80 degrees.

Let me know if this is post has been helpful and post a comment or email me at Also let me know if what I have said makes sense. If I need to improve or clarify the information, let me know.

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