Why Hydration Matters, Even When It’s Cold Outside

You might think the risk of dehydration is highest while exercising in the heat and humidity. But it’s still possible to become dehydrated in cold weather. In fact, dehydration can sneak up on you more easily in the cold.

“Everybody worries about hot weather and how it dehydrates you. You’re drenched in sweat and it’s very obvious,” says University Hospitals sports medicine specialist Kevin Killian, DO. The body doesn’t give the same signals in cold conditions. But when you’re exerting yourself in the cold, you need as much fluid as you do in the heat, Dr. Killian says.

How Cold Depletes the Body

As a team doctor for the Cleveland Monsters professional hockey team, as well as high school athletes, Dr. Killian has seen the telltale signs of dehydration in cold weather. “In the cold, you don’t have the same brain response as in the heat, so you don’t feel dehydrated right away. It’s concerning because it happens quicker than the body initially realizes.”

“The athletes will look fatigued. They won’t be as quick. They won’t be as sharp and they’ll start making questionable decisions,” he says. “Any sort of fluid loss is going to cause issues with performance from a physical and mental standpoint.”

Cold weather athletes need to be intentional about water intake, even if they don’t feel thirsty. “With the cold, you’re losing fluid in a bunch of different ways,” he says.

Signs to Look Out For

Dr. Killian explains how cold-weather exertion affects the body:

• “When you’re cold, your blood vessels constrict and that takes the blood flow from the extremities and shunts it to core areas, which actually fools the brain into thinking it’s more hydrated than it is,” he says. “So, the thirst response is not quite there. It takes longer before you feel like you need more water.”
• Because your body is pushing fluid to your core, your brain might feel overhydrated and increase urination, which exacerbates fluid loss.
• Cold, dry air, particularly in ice rinks, requires your body to humidify air you breath. You lose water just to humidify the air you’re breathing.
• In cold dry air, your sweat evaporates much more quickly, so you don’t feel drenched in sweat, especially when wearing moisture-wicking clothing.

Dehydration Effects

Loss of fluid that amounts to 2 percent of body weight is a critical level that will cause a decrease in performance and mental acuity. Dehydration can affect not just concentration but also mood.

“I will see changes in a player’s body language and resilience,” he says. “If they make a bad play, normally calm and level-headed athletes can all of a sudden get very down on themselves and become more frustrated.”

More serious signs of dehydration include panting, dry mouth and not sweating anymore, he says. “These are larger things to look out for. They are danger signs.”

Other symptoms of dehydration include:

• Dark-colored urine
• Dry lips and skin
• Constipation
• Dizziness
• Sunken eyes or cheeks
• Muscle cramps
• Headache

Chronic dehydration can lead to serious problems. Studies have linked habitual low-water intake to higher risk of kidney disease, kidney stones and urinary tract infections. It can also negatively affect the heart and blood vessels, leading to increased risk of cardiovascular disease.

Even mild dehydration can affect heart rhythm and can trigger rhythm disorders in some people. The heart depends on a balance of water and electrolytes to function properly.

Preventing Dehydration

Dr. Killian says hydrating before, during and after playing sports or prolonged exercise is key.

“One of big things about hydration most people don’t think about is eating,” he says. “If you don’t eat meals, you don’t absorb water, you don’t perceive thirst as well ,and you don’t receive the salt and electrolyte content you need to help your body retain the water you’ve had.”

He recommends having a meal and drinking fluids at least four hours before playing a sport. This ensures you will have enough fluid and also gives you time to urinate so that you won’t have to go during your event.

During competition or prolonged exercise like distance running, athletes should have a plan to replace fluids and electrolytes, Dr. Killian says. “During exercise, we want to replace water during that first hour. If going an hour or more, we need to add carbohydrates like a sports drink with electrolytes.”

The easiest way for athletes to gauge fluid loss and replacement needs is to weigh themselves before and after an event or exercise. “The general idea is that for every pound of weight loss, you replace it with at least two cups of water,” Dr. Killian says.

“For high school athletes, we advise it as they’re starting to get a feel for their bodies and are going through changes of puberty. They get a huge growth spurt and all of a sudden, they have a lot more body to hydrate than they did even six months prior.”

Aside from maintaining good health, “Being appropriately hydrated is one of the easiest ways for anyone to increase their performance,” Dr. Killian says.

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Sports medicine specialists at University Hospitals offer comprehensive care for athletes of all ages and abilities, including performance training, on-site surgical services, and physical and occupational therapy.