What Happens to Your Body When You Adapt to the Cold
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Today’s guest blog post is brought to you by SaltStick. More about SaltStick at the end of the post.
As temperatures plummet for the next few months, it will likely be just a little bit harder to get out of bed for your morning run. This is due to the body’s natural response to cold weather, which includes shivering, faster breathing, and a general desire to get to a warmer environment as fast as possible.
Nevertheless, over a period of several weeks, your body will adapt to colder weather, and it will become easier to get in those winter miles. For information on these physiological changes and tips for how to make the process easier, we’d like to share the science of cold adaptation with you.
Keep up the winter training!
Four Physiological Changes That Occur During Cold-Adaptation
Interestingly, the human body seems to be less efficient at adapting to cold weather than it is to hot weather or altitude.
“Ultimately, we are a heat-adapted species,” said Josh Snodgrass, an anthropologist at the University of Oregon, Eugene, told Discovery. “Even populations we think of as quintessentially cold-adapted, like Siberians or the Inuit, are not that far removed from human ancestors that adapted to heat. Our bodies are just not as good at dealing with cold.”
(For fun: Check out our post detailing what happens to your body when you become heat-adapted here.)
Don’t let that discourage you though! While cold adaptation typically takes twice as long as heat adaptation (or four weeks as opposed to two weeks), the body undergoes the following changes, which ultimately make running in the cold much more tolerable:
- Your blood vessels change: When skin temperatures dip below 50 degrees F (10 deg. C), blood vessels cycle through periods of dilation and constriction, as your body attempts to manage the trade-off between keeping warm blood close to the internal organs and suffering any long-term damage to the extremities. During periods of dilation, the rush of blood to the skin and extremities causes your nose and cheeks to obtain the familiar red “winter glow.” Before cold adaptation, this process is slow and inefficient. However, as you become adapted — which usually takes several weeks — your body becomes more efficient at shuttling blood back and forth, which produces a less jarring reaction to cold weather. This is why the same outdoor temperature may feel frigid in November but pleasant in March.
- You don’t shiver as much: When you step out of your warm home into cold weather, your body soon begins to shiver, as your muscles contract and relax rapidly in attempt to generate heat. However, as you adapt to cold weather, this shivering response is slowly dulled. As your cardiovascular system gets better at shifting blood between the surface and core to maintain a balanced temperature, the need for excess heat produced through shivering is lessened. A 2000 study published in Experimental Physiology found that regular winter swimmers took longer to begin shivering when exposed to cold water than non-cold-adapted swimmers, “which suggests an important participation of non-shivering thermogenesis in the early [heat-producing] response.”
- Your resting metabolism increases: Like most forms of intense exercise, shivering is primarily fueled by glucose in non-cold-adapted adults, concluded a 1993 Sports Medicine study. However, “repeated bouts of exercise in the cold … result in an increase in fat metabolism,” the study found. The study also noted that resting metabolism seems to increase as the body adapts to cold weather. (For reference, “resting metabolism” measures the amount of calories burned when you’re just sitting on a couch.)
- Your brown fat stores increase: The research about changes in resting metabolism was backed up years later through a 2014 study in Diabetes, which examined the relationship between cold adaptation and brown fat stores in humans. (Essentially, brown fat, unlike white fat, is preferred because it is metabolically active, meaning it helps maintain body temperatures by burning calories. While white fat is typically useless for anything other than storing energy, you want to increase your stores of brown fat if you’re trying to adapt to cold weather.) During the study, five participants slept in a controlled chamber set at a variety of temperatures for four month-long periods. After a month of sleeping in a 66-degree room, the participants’ brown fat tissue doubled, along with their sensitivity to insulin. Resting metabolism also increased during this cold-adaptation phase. Later, when the participants slept in an 81-degree room for a month, all of these changes were reversed.
Will Cold-Adaptation Help Me Lose Weight?
Yes, and no.
Remember, you don’t burn more calories during winter exercise. While it’s true that resting metabolism changes, you won’t actually be burning any extra calories when you go out for your morning run. “shivering burns more calories, but if you’re dressed adequately when you run-and you should be-the rapid rise in body temperature that occurs when you start running keeps you from shivering within a few minutes,” writes Cindy Dallow, a Colorado-based marathoner and nutrition consultant, in Runner’s World.
In fact, you’ll have to take extra steps to guard against some slight weight gain in the winter.
“Athletes take in more calories after cold-weather workouts, possibly because food helps warm us and because our appetites wane in warm temperatures,” Dallow writes. “This is one reason we tend to put on a few pounds of winter weight. The solution, of course, is to keep up your running and be conscious of what you eat afterward.”
Key takeaway: Cold adaptation produces a number of physiological changes that can assist with weight loss (such as changes in resting metabolism and increases in brown fat). However, like many things, these changes are only effective when accompanied by proper diet and exercise.
How Do I Stay Hydrated During Cold-Weather Exercise?
Similar to exercise in the heat, cold weather produces certain physiological responses that you will need to take into account to maintain proper hydration.
For instance, you may have heard that cold weather makes you pee more, which makes you more dehydrated. This is partly true, according to John Castellani, a research physiologist at the U.S. Army Research Institute of Environmental Medicine. Through a process called cold-induced diuresis, cold weather can cause the body to perceive it has too much water available. As skin temperatures drop, blood is shifted to the core. “With more blood in the thorax, the heart says, ‘I have too much fluid on board and need to get rid of some of it,’” Castellani told Triathlete Magazine.
As we point out on our blog, this process mutes the thirst response. In other words, when you are cold, you are less likely to feel thirsty when you lose fluids. Once you warm up, your brain can process the state of your extremities, and you realize you are very dehydrated. (This process should sound familiar if you have ever spent several hours in the snow feeling fine, only to return indoors and realize you are ravenous and extremely thirsty.)
Key takeaway: Thirst is a good indicator for low fluid levels in warm temperatures, but you can’t rely on thirst alone when it’s cold outside. You still need to drink water and replenish electrolytes during your winter running.
Two Tips for Making Cold-Adaptation Easier
Now that you know about the changes that occur during cold-adaptation, we’d like to share some tips with you to help make the process easier.
- Use friends and family as a distraction: When studying the people who live in the extremely cold, northern environments of Alaska and Siberia, Snodgrass found an interesting commonality: During winter, the cold-weather residents focused on relationships with family and friends as a coping mechanism.
“They’re almost psychologically hibernating for the winter,” Snodgrass told Discovery. “They emphasize what’s good. That’s how a lot of people make sense of it.”
Apply it: Don’t hibernate! Instead, keep going to your running group, even if it is bone-chilling outside at 6 a.m. Try hosting a warm dinner party for friends. Winter squash and dark leafy greens — two ingredients in most healthy winter stews — are in season during the winter. Keeping in close contact with friends and family over comfort food will help you forget about the cold in no time.
- Use bodily-awareness to stay safe when working out: Remember from above that one of the body’s responses to cold weather is to shunt blood away from the surface to keep internal organs warm. Initially, the body cycles through periods of dilation and constriction of blood vessels. However, as it gets colder, blood vessels stop dilating and instead remain constricted as the body begins to conserve nearly all its warm blood to protect the heart, lungs and brain.
When blood is kept away from the skin and extremities for too long, you can experience “frostnip,” which causes your fingers turn pasty white. Frostnip is not dangerous itself, but it is an early warning sign of frostbite, which is dangerous.
Cold-weather runners should also be on the lookout for signs of hypothermia. This condition is particularly dangerous because it often arises slowly, reducing your ability to notice symptoms, which include hunger, fatigue, confusion, shivering and trouble speaking. Additionally, hypothermia reduces bodily-awareness, which only further decreases your chances of noticing symptoms.
Apply it: While not harmful in the long run, frostnip is an early sign of frostbite, and you should take immediate steps to put on more clothes (or at least thicker gloves!). You should also be on the lookout for signs of hypothermia, which include confusion, constant shivering, slurring of speech, hunger and fatigue. Take steps to warm up as soon as possible.
The above should not be construed as medical advice. Contact your physician before starting any exercise program or if you are taking any medication. Individuals with high blood pressure should also consult their physician prior to taking an electrolyte supplement. Overdose of electrolytes is possible, with symptoms such as vomiting and feeling ill, and care should be taken not to overdose on any electrolyte supplement.
About SaltStick: SaltStick is an electrolyte-replacement product that is uniquely formulated to contain all of the electrolytes lost through sweat in a easily-digestible form. SaltStick is the only electrolyte capsule formulated to closely resemble the electrolyte profile lost during activity: A weight ratio of 220-sodium to 63-potassium to 16-calcium to eight-magnesium for the average athlete. Learn more about SaltStick here or follow along on the company blog, Facebook, Twitter or Instagram pages.
Feature image obtained from Pixabay.com.