Health Matters Blog

Dehydration Also a Cold Weather Risk

Dehydration Also a Cold Weather Risk

By Dr. Peter Foote

Following is part two of a two-part column on cold-weather injuries.

When it’s a humid August day and the sun shines brightly without a cloud in the sky, the perspiration beading up on our foreheads is a reminder to make sure we’re drinking enough water. This is particularly true when you are exercising or working outside and your body is losing fluids more quickly. Furthermore, it is equally important to consume enough water when taking part in outdoor activities during the cold winter months, even if we aren’t sweating or feeling thirsty.

Back in 2005, a study conducted at the University of New Hampshire 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 the journal Medicine & Science in Sports & Exercise, put test subjects on treadmills inside cold chambers and determined the thirst sensation 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 flush 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 up. Severe cases could lead to vomiting, chest and stomach pain, dim vision, confusion and dizziness and a racing pulse. People experiencing severe symptoms of dehydration should seek treatment from a medical professional as soon as possible.

Peter Foote, DO

Peter Foote, DO

Most joggers and runners already know how to do a quick check of their pulse, and this can be a very good way to check yourself for dehydration. You can do this by placing the tips of your index and middle fingers either along your wrist near the base of your thumb or on your neck just below the jawline on either side of your windpipe. Gently hold your hands in either place for a few moments and you’ll begin to feel the throbbing sensation. Then, using a watch or timer, count how many times you feel the pulse during a span of 10 seconds; multiply that number by six to know how many times per minute your heart is beating. By checking your pulse first at rest and then during periods of activity you’ll know how elevated above normal your heart rate gets when exercising or working. Because the volume of blood decreases when the body is dehydrated, your elevated heart rate is telling you to take a water break.

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, such as Gatorade or Pedialyte, contain sodium and potassium that your body needs in order replenish its electrolytes, which are important for cell function. 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. It’s also vital that you drink water slowly when you are dehydrated. Take small sips and pause for a while in between each drink to let your body readjust.

It is usually easy enough to prevent dehydration by getting into the habit of ingesting 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.

If cold water doesn’t sound appealing to you on a winter’s day, green tea is a good substitute as it is also non-caffeinated and calorie-free. The bottom line is that activity is crucial throughout the cold weather months and water is the fluid that your body needs water to enable you to continue to perform at the same intensity relative to other times in the year.

Peter Foote, DO, is a primary care physician at the newly established Brattleboro Family Medicine practice, which is part of BMH Physician Group. He can be reached at 802-251-8455.

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