Hydration / dehydration: impact on health and productivity
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Click here to see an image from the Mayo Clinic on water and the human body (will open a new window)
Let's start by talking about the human body for just a bit. We've all heard that water makes up 70% of the human body. Well... even that's not entirely true. 70% is pretty much a maximum in a range from 55-70%. Men average a bit higher than women. Thin people (yes, thin) average higher than fat people. The reason women and the obese have lower average percentages is that fat literally displaces water... so as it turns out, hydration can be more of an issue for them... dehydration can hit them more quickly and have a greater effect.
Water is central to every activity in the body. It moves materials around. It is the basic ingredient of the suspension parts for a smoother ride. It works as the cooling agent. It acts as the lubricant in our gut helping to move product to it's final destination. So, it keeps our insides clean, cool, comfortable, and moving... water is involved in every activity of the body.
Without water we experience decreased function very quickly, and death is quite rapid (literally a few days... rarely more than a week). A 3% drop in hydration will be very noticeable in all individuals, and a 15% drop is deadly (most don't actually survive that level of dehydration) So you can see how critical maintaining proper hydration levels is. Fortunately we are equipped with a very good system for maintaining top-up levels: our kidneys can eliminate a lot of water in a hurry, and our hydrostatic system is very efficient, so being over-hydrated is actually fairly hard to accomplish or maintain. Interesting factoid: we can only absorb about a litre of water per hour... so if you were to sit down and drink a gallon, it would take about four hours to be absorbed... and would generally be eliminated just as fast! The problem with that level of hydration is not the water, as the kidneys can usually take care of that... it is the loss of electrolytes (notably sodium) that causes the problems associated with drinking too much water, especially and usually in a high-physical-stress situation such as sports, hard physical labour in a hot environment, etc.
What is remarkable in the literature is that it consistently indicates a significant loss of performance as we dehydrate, and that loss occurs remarkably early in the dehydration cycle. A 2-3% drop in hydration level will incur reduced short-term memory, decreased cognitive ability and decision-making skills, loss of balance, increased fatigue, and measurable (and significant) drops in physical output (12-25%, depending on the type of activity and level of dehydration). All of these effects listed above have been repeatedly studied and replicated, and so we can safely assume that these are real phenomena. Surprising, isn't it? A couple of glasses of water a few times a day, and you can think better, remember better, and get more work done more safely? Really? Yes... really.
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