(I can’t find another on this topic, so I’ll start one.)
This reads like “it’s a fundamentally worthless idea”, but I don’t see why. Maybe the effect is higher in the first few minutes as your skin adapts to prevent heat loss, but it can only do so much. If you go out in the cold, you don’t stop shivering after a while. You continue shivering as long as you’re in the cold.
What’s the source for this? Your body generates heat microscopically inside cells by converting fat into heat energy, and macroscopically by shivering muscles, which I don’t see as being any different from exercising skeletal muscles.
Only if you are inadequately dressed for the conditions. Otherwise you shiver to generate heat from your muscles, and stop when you have warmed up. If you are inadequately dressed, or conditions are extreme, you will lose heat as fast or faster than your shivering can generate it, so it will continue. But that’s your fault, for going out inappropriately clothed.
If the temperature is below a given threshold, shivering will continue. The body doesn’t “adapt” to all conditions/environments, as it could be implied by the section gominthe pointed out.
Adaption - If your body is frequently chilly, perhaps after a few months or years you add fat for insulation and to ensure you have the stored energy to generate that heat?
I guess the opposite question would help resolve this… Do people in hot climates (who don’t live in air conditioning) tend to be lighter, less fat?
I had read something once that suggested the lack of championship-level African swimmers was due to their lower body fat level which made them less buoyant. Or maybe it’s just the lack of clean swimming pools in Africa or inner-city America?
Dunno. I keep the thermostat significantly lower than average in the winter and higher in the summer, and there’s no doubt that I lose a good deal of weight during the winter months (I only have to compare the labels in my woolly trousers and cotton shorts to confirm this). This despite a considerable increase in caloric intake during the winter.
Note that I’m not talking about a few degrees here. A thermometer on my desk currently reads 63.9 degrees, and I’m sitting here in shorts and a T-shirt enjoying the relative warmth (thanks to the ballooning cost of propane, February has been irritatingly chilly, even for me).
Now, is it down to homeostasis? Maybe. It’s also equally plausible that, during the summer (East Texas), it’s just too freakin’ hot to move.
I rather suspect that people who live in hot climates sans air conditioning are more physically active than the Western norm.
Even taking that into account, who do you look at? Africans? Pacific Islanders? There are some really striking morphological differences among different populations in tropical climates.
I can’t help but think of the Simpsons episode in which Homer is watching the '84 Olympics:
“You have to remember that many of these competitors come from countries where there are no swimming pools.”
