The snow is deep, the sun is out (most of the time) and the corn is fresh for harvesting.  Spring skiing is here, and this year may even stretch into summer and fall skiing with the solid snowpack.  With warmer days come a few more things to be aware of when out for long day skiing, and this article will address one of them-- appropriate hydration.

Hydration can get confusing when you read various articles attempting to provide advice and can be dangerous if you practice unsafe intake habits.  In reality, for a one day or shorter outing, overhydration is more dangerous than underhydration.  Drinking too much, coupled with some physiologic changes that occur with exercise, can lead to free water overload and hyponatremia (low sodium) which in turn can cause confusion, coordination problems, pulmonary edema (fluid in the lungs), seizures, and even death.  Additionally, electrolyte or sodium supplementation in sports drinks has not been shown to prevent this dangerous condition if you are still overdrinking.  And this overdrinking is not the New Year’s Eve overdrinking, it’s just taking in too many fluids.

For many years drinking large amounts of water was advised in endurance activities due to concerns of dehydration.  It was thought that fatigue, muscle cramps and even altitude illness were a result of dehydration.  These assumptions are all false, and in the past 20 years research has debunked the strategy of water loading.  Athletes can tolerate moderate dehydration with only minimal impact in overall performance or fatigue.  Muscle cramping is still somewhat of a mystery, but most evidence points to a neurological source; nerves connecting to muscles become overwhelmed and misfire due to overworked or undertrained muscles.  Multiple scientific studies have tried to link dehydration or electrolyte imbalances to cramping and have shown zero link between them.  

So what is an appropriate hydration strategy for a day in skiing in the mountains? It depends on how hard you are exerting yourself and how long you are out.  Regarding length, hydration really is not too much of a concern with anything under 90 minutes.  You could get by without needing much if your ski day is in this time range.  Once you move up in time and distance you will likely need to start thinking of hydration.  The next step is to determine how hard you are working.  If you are primarily at a conversational pace, i.e. you can carry on a short conversation or sing Taylor Swift tunes while you are skinning, then a “drink to thirst” strategy is best.  This basically means that you drink when you feel thirsty or as you want, kind of like your canine companion.  Typically this will be in the range of 10-30oz per hour, but do not have a set amount to drink on a schedule (unless you use another strategy that I’ll discuss regarding sweat rates).  If you drink a set amount on a set schedule this can lead to overhydration and the resultant dangers of hyponatremia.  If you are exerting yourself harder than this you can still use a drink to thirst strategy, but you may benefit from doing a home sweat rate test. In order to determine how much water you lose, all you need is a scale.  Weigh yourself without clothes before you go ski.  Go ski for 2-3 hours at your normal exertion and do not eat or drink anything (you may be a little uncomfortable but your body will tolerate this).  Then weigh yourself, again with no clothes, when you return. The amount of weight loss will roughly approximate the amount of fluid that you should be taking in—one pound of weight loss for 16 ounces of fluid needed or one kilogram of weight loss for 1000 mL of fluid needed.  There will be some variability if you urinate between weighing yourself but can still provide a rough estimate.  This will also vary depending on weather, temperature, etc. but can still give you an idea of your fluid intake needed on a typical day.

One final question to address is what to drink.  Should it be only water? Sports drink? Water and electrolyte tablets?  Beer?  Plain water is fine in most cases.  Neither sports drinks or electrolyte tabs have been shown to prevent hyponatremia, but they may delay the onset so you can consider these.  Don’t rely on drinks for hydration that are diuretics, such as beer and caffeine containing sodas.   On a side note there was an exercise physiologist that performed an experiment on himself, using only beer for hydration during a marathon.  It didn’t go well, but I’m pretty sure he enjoyed the after party.  If you are looking for additional calories then a sports drink may work well for you, and for long days in the mountains you will certainly need some caloric intake, but fueling is a whole additional topic that we will not cover here.

In summary the main points are:
Overhydration can be more dangerous than underhydration, although both can make your day miserable
Drink to thirst for most moderate activity
Consider taking a sweat test for increasingly strenuous activity
Your cramps are likely not due to dehydration

Enjoy the mountains, the long ski season and the sun!

Courtesy of Tahoe Wilderness Medicine