Bonus Knowledge
Everything here is from my own research, experience and opinion. Others may have different experiences and opinions. All text and photographs Copyright Marc Walton.
Vasoconstriction and Vasodilation
Cold body = cold feet
Vasoconstriction is when your core body temperature drops, and your body constricts the blood flow to your arms, legs, feet and hands. It does this for a very good reason, it does this to preserve the function of your core organs at the expense of your extremities, hands and feet. It is keeping the nice warm blood close to your key organs so you can still function. So, if you are out and you start to feel your hands or feet start to get colder, then it could be because your core is not warm enough. You could throw on another top/jacket or even just a hat may do it, if you don’t have one on.
Now, for this to work you do have to be dressed for the conditions. If you are out in January wearing sandals on the beach and your feet are cold, it is because you are wearing sandals on the beach in January, you would have put on a lot of clothes to keep your feet warm. So, consider this when dressed for the conditions. “If your feet are cold, wear a hat” – Gerry Cunningham.
Cold feet = cold body
I learnt on a first aid course that blood flows to your feet/hands on the inside and then flows back to your heart on the outside. Basically, blood flows down to the extremities and comes back again. So, whatever you have on at the extremities can have an effect on your body temperature.
For example, I once went to the beach in a brand-new pair of rubber boots in winter. On top I wore a jacket that also keeps be warm, no problem. During this brief trip I have never felt so cold on a walk before. I felt cold from the inside, it was horrible. My conclusion was that these boots had 1) come straight from being shipped and stored in cool/cold conditions and held that coldness until warmed up. 2) The boots being rubber had no insulation what’s so ever. My feet were really cold, and so was my body.
Warm feet = Warm body.
I heard another story were a person was out walking in freezing conditions for 3 days. In this time, he had to cross rivers were his boots and feet got wet. However, in his boots he had very good insulation even when wet and his feet stayed warm although they were wet, during this time he also lost his hat and his hair froze. However, he was never cold, and he survived to tell the tale.
Vasodilation
This happens when your body starts to get too warm. When your body gets too warm it increases the amount of blood to the extremities and to the skin surface to help cool off a little. So if you find that you have really hot feet or hands then you could be too warm and you need to cool down a bit. I have experienced this on walks in winter. Once I wore a jacket on a days walk that I kind of new it might be too warm for the day. The temperature was about 5 – 6 degrees C.