TPS Archives

Reprints From The Professional Skier

Fall 1997 - "Drink Up! The Importance Of Staying Hydrated While Skiing" by Ed Burke, Ph.D, and John Siefert, Ph.D.

This article is reprinted from The Professional Skier. All copyrights apply. Please see our copyright and disclaimer notice page.

There are three times when skiers should drink water: when they are thirsty, when they aren't thirsty, and in between.

In other words, skiers need to make a conscious effort to maintain hydration. This is because the very nature of skiing--with its potentially high levels of exertion in the cold, dry air of the mountain environment--makes skiers susceptible to dehydration and the negative effects associated with it. Dehydration, which occurs whenever fluid is lost from the body faster than it can be ingested, is probably the most common cause of premature fatigue during a long day of skiing. Even small degrees of dehydration can impair physiological function and hinder skiing performance. Moreover, dehydration can contribute to accidents, injuries, hypothermia, frostbite and acute mountain sickness.

Facts About Fluid Loss

To ski effectively, you need to know how cold affects you and alters your fluid requirements during a long day on the slopes. Skiing in cold weather does a couple of things to your body. First, when exerting yourself and wearing appropriate clothing, your core temperature will rise. Your body reacts to this increased temperature by automatically channeling more blood to the skin to initiate sweating. It is this loss of body fluids through sweating that adjusts your body's equilibrium. When you don't replace this water and become dehydrated, your body will stop sending blood to the skin, thus shutting down the sweating mechanism-not a good thing when your body is trying to dissipate heat. Simply put, you need to keep replacing water to ensure that you keep sweating so that you can keep skiing. Second, when you sweat in cold weather and don't replace fluids, blood volume decreases. Less blood returns to your heart, so it pumps less blood per contraction. Your heart rate must increase to pump the same amount of blood as it would if your blood volume was maintained, so you cannot sustain as fast a pace.

Dehydration can catch you off guard. If you replace less fluid than you lose, you may ski poorly and not know why. Exercise physiologists have estimated that sweat loss can reach about 4 pounds per hour under conditions of moderate to heavy exercise at 0 degrees C in clothing that would normally be worn when alpine skiing (Murray 1995). Fluid losses of 2 to 4 pounds will lead to loss of power, coordination, fine motor skills, endurance, and the ability to think clearly--all due to a combination of dehydration and cold exposure.

While the above fluid losses may sound extreme, it would not be uncommon during three hours on the slopes for a 150-pound skier to lose 3 to 6 pounds of fluids, representing a 2 to 4 percent loss in body weight and a possible 6 to 8 percent performance decrement (Murray 1995). A drop in body weight as little as 2 to 3 percent, due to dehydration, has a negative impact upon your muscular strength and endurance (American College of Sports Medicine 1997). Of course, sweat rates range widely among skiers, varying from as little as half a pound in an hour of light skiing in the cold to more than three pounds during intense backcountry skiing on a warm day (Askew 1989).

More Lessons In Loss

Fluid loss among skiers is not limited to sweating. The low relative humidity of the cold, dry air of the mountain environment, combined with rigorous skiing, results in marked insensible water loss through respiration. Here's how: The humidity of cold air is lower than that of warm air, which is why your throat feels much drier in the winter. To compensate, the respiratory passages in your throat and lungs moisturize all air inhaled but do not reclaim the moisture in the air exhaled. Therefore, as you exhale you lose lots of water in the form of water vapor. (This is why you can see your breath when out in the cold.) It's possible to lose 2 to 4 pounds of water each day while skiing and also while talking in a cold, dry environment.

In addition to fluid lost through sweating and respiration, skiers lose still more water through increased urine production in cold weather. The medical community calls this phenomenon cold-induced diuresis. One school of thought holds that exposure to the cold while standing in a lift line or sitting on the chairlift results in peripheral vaso-constriction, in which blood is shunted toward the core of the body to protect vital organs. This causes core hyper-volemia, which the body responds to by increasing urine production to get rid of "excess" water.

Harmful Consequences

More serious than the deleterious effects it can have on your skiing performance, dehydration can also play a role in hypothermia, frostbite, and acute mountain sickness. Peripheral vasoconstriction--combined with a decrease in blood volume caused by sweating and insensible water loss from breathing--means that less blood is flowing to your skin and extremities. This loss of circulation reduces the body's ability to warm itself, which increases the susceptibility to hypothermia and frostbite. Not only is dehydration a risk factor for these conditions, but dehydration usually exists in people suffering from hypothermia.

Proper hydration is critical-mandatory is not too strong a word-to preventing acute mountain sickness (AMS). Often the headaches, nausea, and dizziness associated with AMS can be prevented with proper hydration. One problem in diagnosing AMS is that it can be confused with dehydration, carbonmonoxide poisoning, etc. Headaches, nausea, and dizziness should be attributed to AMS (or altitude) until proven otherwise. You can clear the air by making a strong effort to stay hydrated so that dehydration is not part of the differential diagnosis. One way to gauge dehydration is to monitor the urine output. Scant amounts of dark yellow urine indicate dehydration. The lighter the color and the more frequent the urination, the better the state of hydration. Especially as it relates to AMS, it is crucial to emphasize to your clients the importance of hydration. AMS is not an inevitable feature of skiing in the mountains; it is preventable and treatable. It need not spoil an expensive skiing vacation.

Keeping The Tank Full

As stated before, you may lose several pounds of water during a long day of even moderate skiing. You simply cannot drink enough to keep up with the loss, so the longer and harder you ski, the greater your fluid deficit will be. Under these conditions, you'd be foolish not to consider taking in fluids while skiing and giving lessons.

You need to think about keeping the tank full not only during one particular day of skiing, but for the next day and the days that follow. This means planning ahead. Before your first run, focus on drinking enough water to ensure that you are fully hydrated. Don't just drink when you're thirsty--thirst isn't a reliable indicator of your body's fluid levels. (Studies have shown that you have to be about 2 percent dehydrated before you become thirsty.) Also, since it takes time for your body to absorb water, drink small amounts of fluid consistently rather than chug 2 liters of water all at once. The American College of Sports Medicine recommends slowly drinking a half a liter of fluid about two hours before exercise to ensure adequate hydration and allow time to excrete excess water.

Weigh yourself before and after a day of skiing, then gradually drink enough to bring your weight back up to normal before you retire for the evening. Since your blood and other fluids help remove waste products and bring nutrients to tissues for repair, replacing lost fluids as quickly as possible will speed up your recovery from a hard day of skiing.

Best-Bet Beverages

Your top two beverage choices are water and the carbohydrate-replacement drinks known as sports drinks. Nothing beats water for pure hydration, but sports drinks-which contain 6 to 10 percent carbohydrate in the form of glucose, sucrose, or glucose polymers-are good choices while skiing because they not only replace fluids but supply carbohydrates to your working muscles. The advantage of replacement drinks is that they're absorbed as quickly as water and provide the energy that can boost your performance when you plan to ski longer than an hour. Plain water is just as good if you bring along a sports bar or carbohydrate gel.

Neither you nor your clients should rely on caffeinated drinks like coffee, tea, and colas to replace fluids, because caffeine is a diuretic, and beverages containing this substance actually leave you less hydrated than before. Beer and other alcoholic beverages similarly will draw fluids from your system. If you drink caffeinated beverages or alcohol, drink extra water to balance the dehydrating effect. Keep in mind, however, that aside from its correlation to dehydration, alcohol also impairs mental and motor skills necessary to ski safely. If you drink, keep your alcohol consumption to one or two drinks during the evening hours after skiing to reduce the diuretic effect of alcohol.

During your time on the slopes, the maximum you should drink is the amount that can empty from your stomach. Research has shown that most individuals' stomachs can empty only about 6 to 10 ounces of fluid every 15 minutes during exercise. Amounts greater than that will just slosh around in your stomach. Some people process more or less than this, so experiment with how much your stomach will tolerate (table 1 below).

A skier can avoid dehydration by matching sweat loss with fluid intake. For example, a skier who loses 16 ounces through sweat over a one-hour period should drink four ounces of fluid every 15 minutes to remain well hydrated. One medium mouthful of water is about one ounce.

It would be safe to say that most alpine skiers do not give much thought to drinking fluids while skiing for two to four hours on the hill. And, those who do often struggle with convenient ways to carry water while skiing and wonder how to keep it from freezing. In addition, the only place where fluids are available is at the base lodge or midmountain restaurant, which requires a lot of time away from skiing. For these reasons, fluids often are not consumed while skiing on the hill.

Best Advice

The best skiing hydration advice is to carry fluids with you while skiing, and not wait until you're thirsty to drink them. Remember, there are three times when you should drink water when skiing: when you're thirsty, when you're not thirsty, and in between. You might want to consider using a hydration system that allows you to carry water with you while skiing. At the very least, you'll want to make a conscientious effort to hydrate whenever possible. Consuming fluid while skiing can improve your performance and endurance and increase your safety on the slopes.

Practical Recommendations

The scientific and medical communities have established the need to stay well hydrated while exercising in the cold. In light of this, you may want to educate your clients about the benefits of proper hydration. Here are some tips to pass along to your students to help them make the most out of a day on the slopes.

aDo whatever it takes to make it easy to drink fluids during the ski day. Carry fluids with you in a back- or hip-mounted hydration system or stop to drink at a ski patrol station or on-hill restaurant as often as possible.
aPrehydrate! Drink about 10 to 16 ounces before you make your first run of the day.
aDrink plenty of fluids with your meals.
aKnow where to find fluids on the mountain.
aOne reason to stay well hydrated during skiing is to reduce sweat loss. Wear clothing that can be ventilated and will not allow you to overheat while skiing.
aDrink before you are thirsty and drink often.

By sharing this information with your students, you can help them stay hydrated and maintain the blood-glucose levels that just might help them ski better, enjoy the lessons more, and get more out of their lesson application on the hill.

- Ed Burke

Ed Burke, MD., is the director of the sports science program at the University of Colorado at Colorado Springs. He is a former ski patroller at Colorado's Ski Cooper ski area.

John Seifert, MD., is an assistant professor at St. Cloud University in St. Cloud, Minnesota, and has worked with the U.S. Ski Team within its sports science program.

Both authors are currently conducting research for Camelbak Hydration Systems on the use of back-mounted hydration systems while skiing and cycling.

Recommended Reading

American College of Sports Medicine. 1997. Heat and cold illness during distance running. Position paper. Indianapolis.

Askew, E.W. 1989. Nutrition for a cold envi ronment. The Physician and Sportsmedicine 17 (12): 77-89.

Murray, R. 1995. Fluid needs in hot and cold environments. International Journal of Sports Nutrition 5: S62-S73.

Murray, R. 1996. Drink more. American College of Sports Medicine's Health and Fitness journal 1(1): 19-23, 50.

Weiss, H. 1988. Secrets of Warmth. Brooklyn: Vibe Publications.

Wilkerson, J., C. Bangs, and J. Hayward. 1986. Hypothertnia, Frostbite, and Other Cold Injuries. Seattle: The Mountaineers.