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Asked by jamieleigh leathem to Andrew, Dan, Emilia, Helen, Katy, LauraAnne, Stephanie on 4 Nov 2016.
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Helen Hanstock answered on 4 Nov 2016:
Our bodies have a few different ways of dealing with the cold.
Firstly, our blood is warm and helps to spread warmth around our body. But, when it is cold outside our bodies try to keep that warmth for the most important organs such as the brain, heart etc. So, the blood vessels in our skin become narrower so that we lose less heat through the skin. This means our extremities such as fingers and toes start to feel cold before our core does.
We also may start moving around more and shivering. Muscle activity generates heat, and shivering is a special type of muscle contraction that helps to keep us warm. Our metabolic rate also increases to try to generate more energy for shivering and heat through the metabolism of brown fat.
It’s possible that our bodies still might not be able to generate enough warmth to maintain core body temperature at 37C. If core body temperature drops below 35C we call this hypothermia.
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Dan Gordon answered on 4 Nov 2016:
What a great question and certainly which is pertinent to athletes training and competing in cold climates. In order for our body to operate effectively it needs to be maintained at a relatively controlled temperature of around 37 degrees C. The primary means by which heat is either retained or removed from the body is through the movement and redistribution of blood. The blood is an incredibly useful mechanism for moving heat around the body. So when we start to get cold and the ‘core’ temperature starts to dip below 37 degrees C the blood flow is re-directed away from the skin. Why does this happen? Well in order for us to get rid of excess heat from the body blood flow is directed to the skin allowing for heat to be passed out of the body into the environment. But when you are cold, this is not a good process. So the blood flow is directed to the core to retain this heat. Coupled with this is the fact that we start to generate involuntary muscle contractions, we shiver. Shivering is a good process because as the muscle start to contract they generate heat. This heat is then retained through the blood being directed to the core. Additionally you metabolism starts to increase. This is important because for any process like metabolism to occur there are chemical reactions, all reactions generate heat as a by-product, thus enabling us to generate more core-heat. But of course I am sure you can appreciate that there will come a point (outdoor temperature) when these process can not compensate for the low temperatures and we start to loose more heat than we retain, this is the condition know as hypo (low) thermia (temperature) hypothermia.
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LauraAnne Furlong answered on 4 Nov 2016:
I’ll leave the systems physiology to those who know it better than I do 🙂 but while it is definitely not a good idea to go out in freezing temperatures without being properly dressed, there’s actually an area of research which looks at how going into whole body freezer chambers (at temperatures of between -100 and -130 degrees Celsius!) with only minimal clothing can be used for athlete recovery after exercise. Because these are so cold, you can only go into them for 2-4 minutes at a time. It is called cryotherapy and you might have heard it mentioned on the TV after rugby matches for example.
Helen and Dan have explained how when we get very cold, our body adapts to try to keep us warm by making our blood vessels very narrow and forcing all the blood to our chest area and brain (the important bits). This happens in the cryotherapy chamber too, but when you come back out of it, it is thought that the extreme changes in temperature can stimulate a healing response in injured muscles as the blood returns back to where it should be. It’s a very popular treatment for injuries, with lots of famous teams and athletes using it, but there is very little good quality scientific evidence to support its claims that it speeds up recovery in damaged muscles or makes muscles feel any less sore.
Not quite what you asked, but its an application of where freezing was thought it might be able to do some good! Also worth noting there are still the same risks going into a cryotherapy chamber as there are going into those sort of temperatures outside – Justin Gatlin got frostbite on both his feet in 2011 when he went into a chamber with wet socks!
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Emilia McAllister-Jepps answered on 6 Nov 2016:
Hi Jamieleigh, I think the Physiologists have done a better job explaining the bodies reaction to being freezing. But also great to see that whilst in many ways you wouldn’t want to be freezing, it can also help recovery from a training session.
I thought I might be able to tell you a little bit about how my body feels when I start to get cold when out on the water. The process that Helen describes, with our extremities being the first part of the body to feel cold, from experience starts to show with it being more difficult to hold my paddles properly. It can also make the skin feel very sensitive to touch….and when you begin to warm back up again you have to remember that you are freezing, so anything even slightly warm feels very hot. You can sometimes even see the change in colour when your hands start to get colder!
To get the best out of my muscles in the cold weather, I try to avoid wasting any energy being cold or shivering. So I always wear plenty of layers and a waterproof splash deck.
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Katy Griggs answered on 6 Nov 2016:
The other scientists have provided some great information here on hypothermia and how it occurs, so i wont repeat the information. But just to add some of the signs of hypothermia to look out for. A person suffering from hypothermia may have slurred speech, changes in their breathing from fast to slow and shallow, drowsiness, confusion, cold or pale skin and a weak pulse.
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