Hydration at the Extremes: It’s Not Just a Heat Issue

Headaches, nausea and confusion are wearing you down and you can’t continue. “I have to turn back,” you mumble, calling an end to your bucket-list adventure trip. Months of hard work and training are wasted, and you ask yourself how this could happen. The answer is likely dehydration.

Dehydration, commonly perceived as a heat-related illness, can strike under many other conditions such as high altitude, cold and high-humidity. The symptoms are miserable, including fatigue, nausea, lightheadedness and more. Additionally, dehydration increases susceptibility to other conditions such as hypothermia. Certainly not something you want to deal with on your next adventure!

While the danger of dehydration in hot weather is well known, in other environments it’s more insidious. Don’t let it sneak up on you, and be especially careful to hydrate under the following conditions:

Cold

Hydration in cold weather is critical to maintaining blood-volume and preventing hypothermia, but it needs to be a conscious effort.

“People just don’t feel as thirsty when the weather is cold,” says Robert Kenefick, associate professor of kinesiology at the University of New Hampshire. “When they don’t feel thirsty, they don’t drink as much, and this can cause dehydration.” Additionally, the drier cold air increases the amount of fluid lost during respiration and by sweating.

To guard against dehydration during cold weather, make yourself drink at regular intervals, even when not thirsty, and make sure that your fluids are easily accessible. A water bottle stashed deep in your pack is inconvenient and frozen hydration packs are nothing but dead weight. Prepare for winter sports by making sure you have a bombproof hydration system handy that won’t freeze-up when you need it.

Prevent the hose of standard hydration packs from freezing by blowing the water back into the bladder between sips and stowing the tube close to your body. Also, look for an insulated tube and place a hand warmer in the pack to raise the temperature in the bladder. Some folks suggest buying an oversized jacket and wearing the pack underneath to keep it warm, (I haven’t tried this personally). If using a Geigerrig pressurized system, I suggest adding the Insulated Tube Garage, which includes a built-in hand-warmer slot to prevent the tube and bite valve from freezing.

Most hydration packs available today will freeze in extreme sub-zero temperatures, such as those encountered during mountaineering. A new hydration pack option co-developed by NASA Astronaut Scott Parazynski, prevents water from freezing for up to 12 hours at -40 degrees Celsius. The pack, called High Altitude Hydration System (HAHS), is not on the market yet, but has already been tested on Mount Everest. My guess is it won’t be cheap!

Altitude

People often confuse the symptoms of dehydration with altitude sickness; however, dehydration is responsible for more illness than oxygen insufficiency at moderately high altitudes.

High elevations are often cold creating a “double edged sword.” Increased fluid loss due to rapid and deep breathing of frigid, dry air is the primary cause of dehydration at high altitude. Above 15,000 to 16,000 feet, fluid requirements often exceed four liters per day.

In addition to the cold, dry air, “…one of the first things to occur in response to exposure to a higher elevation is a rapid reduction in the amount of water that circulates within your body. This rapid elimination of water from your body, through urination, concentrates red blood cells that carry oxygen in your blood, and this helps to offset the thinner air at altitude,” explains Dr. Christopher D. Jensen in Challenges of High-Altitude Sports.

Humidity

In high humidity the air is full of water, yet your body is depleting it’s fluids at an alarming rate while working harder to cool itself with sweat. In theory, the sweat should evaporate and cool the body, but in high humidity, it doesn’t evaporate fast enough to do the job. In response, the body produces even more sweat creating a vicious circle requiring extra fluid intake to prevent dehydration.

 Tight Spaces, Funky Places and Caves

Sometimes people don’t hydrate enough because it’s too much trouble. For example, when I’m crawling around in a muddy cave, digging a bottle out of my pack with my dirty paws isn’t easy. Alternatively, if I wear a hydration pack, the bite valve ends up slathered in mud, yuck! Not to mention, my packs get severely beat up.

For these conditions, I look for durable materials, a snug stable fit, and the ability to function in weird positions (no comments on that please…) I also use a cap on my bite valve or stow it under my clothes.

The Geigerrig

Although the primary purpose of this article is to explore hydration in extreme conditions, I also examined how well suited the Geigerrig pack is to these environments. Overall, I loved the pack. It’s constructed using Ballistic Nylon fabric and heavy-duty coil zippers; it also fit my frame well thanks to lots of adjustability. My favorite features were the pressurization and ease of cleaning.

I irrigated my sinuses repeatedly while getting used to the valve, but now that I’m used to it, I like that the pressurized system works in any position, even upside-down. I also like having a way to rinse my hands in a muddy cave before I use my camera.

As for the cleaning, no more science experiments in the bladder. The Geigerrig bladder opens completely and can be turned inside out and placed in the dishwasher. I didn’t test any flavored fluids so I can’t say if it retains taste.

In Conclusion

Give hydration more than just a passing thought when planning activities in extreme conditions. Before you leave, know how much water you will need and how it will be stored. Invest in good gear and test it before the trip. Also, remember that in some conditions thirst won’t remind you to drink, so you should set a schedule.

Start hydrating well before activity, so you’re not behind before you begin. And the best way to know you’re getting enough fluid – drink enough so that your urine output remains light colored.

In this post, I’ve tried to raise awareness about hydration in a few less-than-obvious conditions. Share other insidious circumstances where you’ve found yourself forgetting to hydrate properly, just leave a comment below.

References

• Challenges of High-Altitude Sports, Christopher D. Jenson, PhD, MPH, RD
• Cold Weather Increases Risk of Dehydration, University or New Hampshire Media Relations, January 28, 2005
• Physiological determinants of endurance exercise performance, Department of Kinesiology and Health Education, The University of Texas, Austin, October 1999
• Medicine for Mountaineering, The Mountaineers, Fourth Edition, Edited by James A. Wilkerson, M.D.