As soon as we say the word ‘sweat’, our reaction is ‘YUCK! And of course, the smell, the stickiness, the prickly-heat! If that is so, why the nature made sweat at all, we would have been much better without it, right?
But even I thought so before taking up an assignment as a technical manager in Dubai for a sport-drink made in Japan. For the next several years, it was journey of ‘importance of sweat for people who exercise, run marathons and work outdoors.’ When we do a strenuous physical activity, there is a rise in our core body temperature by several degrees Celsius. It is then our body’s air conditioning system, ‘sweat’ kicks in. Without sweat to cool us, our core temperature will shoot up, and our vital organs will start getting cooked.
When we exercise, our body needs to produce energy to get our muscles and other metabolic processes that keep us going at that high level of stress. The harder the physical stress, the more energy we produce, which increases our internal body temperature. Our brain, that seems to understand the ‘bio-physics’ gets alert, sends signals to our blood vessels that it is time to remove the core body-heat by conduction. The blood vessels near our skin are dilated, increasing the blood flow towards the skin and the core heat is transported to the skin.
Hold your breath, we have about 2.6 million (26 lakhs) sweat glands on our skin. Sensing the heat, they move in and start producing sweat that evaporates from the skin and takes the heat away from us by evaporation.
The most shocking fact is, if the physical activity is done outdoors, in high temperatures, the body produces several liters of sweat to protect us from what is called the heat stroke.
And if we do not replace that loss quickly enough by drinking enough water our body does not have the raw material to make sweat which also contains minerals.
Replacing fluids during and after exercise is vital for staying hydrated and preventing dehydration. Signs of dehydration include dark colored urine, muscle cramps, decreased sweat rate, and increased fatigue.
Our most important nutrient, the humble water, is the colourless, odourless, tasteless, inorganic substance. It is an important solvent for thousands of life sustaining bio-chemical reactions, it helps us remove waste, maintains circulation and also body-temperature. The human body is made of about two thirds of water and one third ‘matter’. Almost sixty percent of our body weight is from water present in our cells, muscles, tissues and blood. So if a person weighs seventy kilograms, the body contains about 40 to 46 liters of water, depending on gender, body-fat and fitness. 65 percent of our total body water is inside our cells, and 35 percent is outside our body cells, out of this 35 percent, 28 percent is floating between the cells and only 7 percent is in the blood. If we do the math, and we have forty liters of water in our body, out of that forty liters only 2.8 liters is in the blood. The body needs to maintain its blood volume at any cost, because blood provides oxygen to all our internal organs. So when we make several liters of sweat to cool ourselves after strenuous activity that water is drawn out from within our cells, our largest reservoir of body-water! That needs to be replaced quickly.
Remember, heat stress, heat exhaustion and even heat stroke are less about how high is the environmental temperature is and more about how hydrated we are, and how hydrated we have managed to keep ourselves. More about how to keep ourselves hydrated in my next article.
The first rule is – when we are thirsty we are already dehydrated.
The second rule is – if we lose just two percent of our body water it robs us of twenty percent our energy.
The third rule is – health is all about maintaining hydration and not treating dehydration!