Which adaptation is characteristic of cold acclimation after repeated cold exposure?

• A. Increased non-shivering thermogenesis
• B. Reduced shivering onset
• C. Decreased tolerance to cold
• D. Decreased vasomotor control

Answer: (A)

Cold acclimation from repeated exposure boosts heat production without muscle work by activating brown fat. The sympathetic nervous system stimulates brown adipose tissue to ramp up mitochondrial activity and express thermogenic proteins like UCP1, increasing non-shivering thermogenesis. This makes heat generation more efficient and helps maintain core temperature in the cold with less reliance on shivering.

While shivering can become less prominent after acclimation, the hallmark change is the rise in non-shivering heat production. Options suggesting reduced shivering onset or diminished vasomotor control don’t capture the primary adaptive mechanism, and a decrease in cold tolerance would be opposite to acclimation.