The human body can be compared to a fully functioning machine, it uses fuel, produces heat when performing work and disposes of waste. The process that allows the body to deal with and compensate for heat production, and to maintain its internal core temperature, is known as thermoregulation. Some main processes that the body dissipates this heat production through are evaporation, convection, and redistribution of blood in the body.
Evaporative cooling is an effective technique that is utilized by the sweating mechanism. It is important to understand how the body can dissipate heat through sweating. If the environment is too humid, then the sweat can’t evaporate from the skin thus making the sweat mechanism useless. The environment can sometimes help the body displace heat due to convection. An example of convection is when wind blows on the body, cooling the individual, lowering the external temperature and allowing the body to work less to cool itself. The last mechanism used is the redistribution of heat throughout certain areas of the body. Blood in the body can be shunted from the body to the skin for convective heat loss. Just like evaporation, the efficiency of this mechanism depends on environmental conditions. If the temperature of the environment is hotter than the skins temperature, then heat will not transfer to the environment, instead the heat of the body will continue to increase. The environmental temperature must be lower than that of the skin to be transferred to cool down the body.
The next question that rises is where is this blood coming from in the body? Is blood being taken away from muscles during exercise to prevent overheating? When comparing blood volumes in exercise versus rest, there is less blood circulating in the organs during exercise than at rest. At rest, the organs account for about 20-25% of blood in the body while during exercise it drops all the way to 3-5%. The reason this drop occurs is to preserve the blood flow to the muscles so they have an efficient oxygen supply. The blood is taken from organs mostly compiled of the digestive and excretory system; this allows heat to be transferred to the skin to cool down the body while preserving the amount of oxygen supply to the muscles. When accounting for environmental factors during exercise there are two main points to keep in mind, air temperature and air humidity. If the air temperature is greater than roughly 36 C or 96.8 F, the heat transfer from the skin to the environment is reversed thus increasing core temperature. When humidity levels reach greater than 60%, the body begins to sweat more but the evaporative effect is inhibited causing no cooling for the body.
As mentioned previously, the two key numbers that you should be paying close attention to this summer are the humidity level and the air temperature. If it is around 97 F outside, continue to hydrate properly, to ensure you have efficient fluids in the body and to help avoid dehydration. Although your body is an efficient machine, it still needs necessary substances to help it run smoothly just like a car needs oil to run smoothly. Provide your body with water throughout the entire day, especially if you are planning to exercise in the grueling heat. Allow yourself to be receptive to when your body is struggling with the heat and make sure you understand symptoms of heat illnesses that can occur. Treat your body well, by giving it fluids and fuel to utilize and in turn it will perform to the best of its ability. While exercising this summer, be aware of the heat and humidity and don’t be afraid to get a little sweaty!
Thermoregulation
By: Coleman Smith
June 2016/ Edge Performance
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