Baby, it’s cold outside

A cold weather Q&A with Dr. Maren Dunn, DO
For a healthy human being it takes somewhere between two and three weeks to acclimatize (to elevation.)

The human body is a remarkable machine which alters depending on surroundings. We started asking questions at a recent staff meeting in anticipation of a cold snap: How do locals fair so much better playing in the cold than people from warmer climates? Why do visitors from flatter areas struggle so much with elevation? We didn’t have the answers, so we asked Doctor Maren Dunn, DO to do a physiological deep dive with us and explain how our bodies adapt.

Lone Peak Lookout: How do our bodies adapt to the cold?

Dr. Dunn: If you really want to talk about cold adaptation, then we’re talking about your body's homeostasis or how it regulates its temperature. It's actually pretty simple. Folks with higher metabolisms or who carry more metabolically active tissue – like muscle – tend to do better in cold climates. One of the body's ways of producing heat is shivering. We're all familiar with that. It does have limitations: it's fueled by glycogen which is muscle storage of sugar, essentially. So, once the muscles are out of stored sugar, shivering stops. Then your temperature continues to drop and you either reach hypothermia or you get yourself warm. 

LPL: How does it work for people who aren’t muscular?

Dr. Dunn: There's also another mechanism that the body uses which is burning brown adipose fat. Again, that has to be on a person who is more stockily built and carries more adipose tissues than someone else. another adaptation I think is interesting is found in people who came from a warm climate to a cold climate. Their bodies learn to not vasodilate as much. Vasodilation is another way the body tries to get tissues warm – the blood vessels dilate and allow blood flow to go to the surface of the skin. In these folks, less vasodilation means less core heat loss.

LPL: I’m not sure about here, but it's standard for snowmobilers in northern Montana to drink a 50-50 mix of blackberry brandy and peppermint schnapps. Gross, I know, but they claim it’s almost medicinal in helping them stay and play in the cold longer. How does alcohol actually impact the body when it’s cold outside?

Dr. Dunn: Alcohol use causes vasodilation: it's why some people will get red in the face and also why if you've been drinking and you go outside you don't feel cold. It's a false sense of warmth. It's a very superficial sense of warm simply because the blood flow is coming from the core to the outside surface That's also why inebriated people may not feel as cold and get themselves into dangerous situations with hypothermia – because they don't feel cold when they are getting cold. They don't feel cold on their outer level when they are getting cold on their core level, if that makes sense. Snowmobilers most likely notice their fingers and toes stay warmer.

LPL: How does the cold affect very thin people?

Dr. Dunn: Thin people with little muscle mass tend to be colder – and probably wear big coats all the time! They don't have the thermoregulatory capability as someone who carries more adipose tissue – which is a fancy word for fat tissue, or metabolically active tissue like muscle. 

If you look at a lot of the people who love living here and being outdoors in the winter, they're stocky or they're muscular and they're fit. The people who complain about cold are typically not stocky, muscular or fit, or they may be overweight. Although overweight people do seem to be warmer., they might not be able to maintain warmth quite like someone with a higher metabolism. 

LPL: How does the body adapt to changes in elevation?

Dr. Dunn: When you first come up to high elevation, your breathing changes because your body feels oxygen debt – you're not getting as much oxygen.  breathing differently causes a complex acid base change in the blood. You also lose water through the increased breathing rate. The kidneys are responsible for managing that acid base change, which is another reason why it's important to stay hydrated when you're going through acclimatization. Then your bone marrow is stimulated to produce more blood cells with a higher level of hemoglobin attached to them so that those red blood cells can carry more oxygen than they would at a lower elevation or at a place where there's more oxygen available. 

When it comes to alcohol use, lowlanders will notice a more intense inebriation at the same blood alcohol content that would not cause inebriation when at lower elevation. This is because the brain is already at a deficit due to acclimatization. Additionally, alcohol drinkers will experience worse hangovers because dehydration will be more severe. So, when people get acclimatization issues or acute mountain sickness, we tell them “Don't drink alcohol,” ‘Don't drink caffeine’ because number one: they will make your symptoms worse and number two: they will cause worse dehydration.

LPL: How long does it take for the body to fully adapt to conditions?

Dr. Dunn: For a healthy human being it takes somewhere between two and three weeks to acclimatize. For less healthy people or ones who notice elevation changes more severely, they should come to elevation slower. In other words, if you're coming from sea level go up to 1,000 feet then to 2,000 feet over a few days. Don't just go from 0 to 6,000 feet, or you'll risk having symptoms because your body just isn't going to be able to manage that big of a jump. there's also a medication that can help people to feel better if they do have to make a big jump. The medication basically perpetuates the kidney's function with the acid base changes so that the symptoms are less. That's a prescription medication called Diamox. 

LPL: Do you see a lot of cases of acute mountain sickness?

Dr. Dunn: We see a lot of AMS in the summer with people who are visiting the Park. In the winter, we see more AMS because people are coming to ski. Our peak seasons always bring acute mountain sickness.

LPL: How can people spot acute mountain sickness?

Dr. Dunn: The symptoms of acute mountain sickness are kind of like a hangover: nausea, headache, symptoms worsen with exertion, some people get a little bit confused or delirious – that's the worst-case scenario. Some people have trouble regulating blood sugar: they may feel really hungry. There are all sorts of interesting things the body tells you to do when it is trying to acclimatize. You may even wake up during night to take deeper breaths. We call this high-altitude apnea. You need to see a doctor if you get headaches, nausea or delirium. Or, go down in elevation immediately. And definitely stay hydrated!

Dr. Dunn, DO specializes in family medicine at Bozeman Health Big Sky Medical Center 
located at 334 Town Center Ave.

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