Health Matters: Dehydration is also a cold weather risk

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Most people think of hot summer weather when they think about dehydration. However, dehydration can occur even during the coldest months. Drinking enough water when taking part in cold outdoor activities is important, even if you're not sweaty or thirsty.

A study conducted at the University of New Hampshire in 2005 found that cold weather makes people feel less thirsty, which in turn increases their risk for becoming dehydrated. The study by Associate Professor of Kinesiology Robert Kenefick, which was published in Medicine & Science in Sports & Exercise, put test subjects on treadmills inside cold chambers and determined that thirst was reduced by as much as 40 percent.

Kenefick said this occurs because our body naturally decreases the outward blood flow as a means of maintaining warm temperatures around the vital organs. However, the warm core temperature prevents our brain from realizing that there has been a temperature reduction in the outer areas of our body and, as a result, the hormones that signal our kidneys to conserve fluid are not released at the same rate they would be in warmer weather. This can all add up to as much as an eight percent drop in fluid body mass during periods of high activity in cold weather. To put that in perspective, symptoms of mild dehydration start to show after just a two percent loss in body fluids.

In addition to thirst, other initial symptoms of dehydration remain the same in cold weather as they are in warm weather, including flushed skin, dry mouth and lips, and a thickening of saliva. As the condition advances, a person's skin may become dry and muscles will start to cramp. Severe cases could lead to vomiting, chest and stomach pain, dim vision, confusion, dizziness and a racing pulse. People experiencing severe symptoms of dehydration should seek treatment from a medical professional as soon as possible.

Water is what you should drink in order to rehydrate. Juice, soda, or other drinks that contain sugar will not help your condition, nor will caffeinated or alcoholic beverages. Sports drinks or pediatric formulas contain sodium and potassium that your body needs in order replenish electrolytes as necessary for cell function, but should be watered down 2:1 to ease the sugar load. You can also restore electrolytes with a salty snack or a banana after you've drunk enough water to make the symptoms of dehydration go away. Drink water slowly when you are dehydrated, take small sips and pause for a while in between each drink to let your body readjust. Adequate hydration will help thin out secretions; helping your sinuses moisturize the upper airways and back of throat, instead of causing thick post-nasal drip leading to a junky cough.

It is usually easy enough to prevent dehydration by getting into the habit of drinking fluids throughout the day. While the age-old advice of "drink eight, eight-ounce glasses of water each day" is not a medically proven rule, it is a good starting point for you to figure out how much water you should drink on a daily basis based on your gender, size and fitness level. Some fitness experts suggest weighing yourself before and after exercising and drinking 20 ounces of water for every pound of weight you drop.

The bottom line is that activity is crucial throughout the cold weather months and your body needs water to enable you to continue to perform at the same intensity relative to other times of the year. Think of hydration before you bundle up to shovel away the snow from our next late-winter blizzard.

John Todd is a nurse practitioner with Putney Family Healthcare, a department of Brattleboro Memorial Hospital.

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