Everyone knows that humans could not run without powerful leg muscles and strong feet that can withstand the impact of running. However, the most important part of the human body for running is not something that is in the body, but rather is something that the body expels: sweat.
Without sweat, human distance running simply would not exist. The reason for this lies in the tremendous heat that running produces in the body. In order to run, the body must metabolize energy sources from the food we eat (i.e. carbohydrates). This metabolism produces a substance commonly known by its shortened name, ATP, which is the fuel that allows the muscles to operate.
The chemical reactions that produce ATP, however, also produce excess energy in the form of heat. If not allowed to escape from the body, this heat can cause significant damage to muscle tissue and internal organs that are not designed to operate in a high temperature environment. If the body could not expel this heat, there is no way that humans could run for a very long time.
Fortunately, humans have an extremely efficient way to get rid of the excess heat through the process of sweating. When the brain senses the massive heat increase caused by running it sends a signal to the sweat glands to release water. This air will evaporate once it reaches the air, which leaves your skin cooler. This built in “air conditioning” allows the body to get rid of potentially dangerous heat and continue running.
Of course, a serious side effect of the sweating process is a loss of water and other minerals that are contained in sweat. This is why it is so critical that runners keep themselves properly hydrated. The general rule is that runners should drink 4 to 6 ounces of fluid for every 20 minutes of running to keep the sweat system functioning properly.
