Re: [Paddlewise] Cold and skills

Robert Livingston wrote:
> Fat is where most of our energy comes from in day to day life. That is 
> where muscles are getting their energy by and large. The glycogen in the 
> liver and glucose in the blood stream would not get you very far. When 
> you go out for a walk, that energy is coming from fat -- not the 
> glycogen in your liver.
> 
> But we need sugar. The biggest problem is the brain. It cannot burn fat. 
> The heart also uses a lot of sugar although it can shift over to more 
> fat if need be.
> 
> There is no pathway from fat to sugar. If you fast for a while then the 
> body will start breaking down muscle to get the glucose it needs to feed 
> the brain. The body can convert muscle to sugar. It cannot convert fat 
> to sugar.
> 
> We cannot just burn fat to stay warm. If we could, that would be great. 
> We can burn fat to move muscles and that generally warms you up but in 
> cold water moving muscles can work against you and eventually we get 
> tired when moving muscles. When we go to sleep we get colder and if we 
> are in extreme environment die. Even though there is plenty of fat to burn.

Great summary, Robert.  Ya gotta have some carbos on board to make use of 
fat over the long haul.  We humans can not manufacture sugars (e.g., 
glucose) from fat.  It has to come from stores (glycogen or, indirectly, 
from proteins) or from fresh input (recently ingested carbohydrates).

Appreciate also, you pointing out in the earlier missive the enhanced loss 
of heat if the muscle tissue is not enveloped in surrounding fat.

I think I'll go eat a brownie, or two, or three.

-- 
Dave Kruger
Astoria, OR
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