When the body is cold, it shivers involuntarily to produce heat and reduces blood flow to the extremities to protect vital organs. To warm up, one should cover their extremities, layer clothing, and move.

noli's read

Marine accurately describes shivering thermogenesis, an involuntary muscular response widely validated by the science of thermal regulation. The redirection of blood flow toward vital organs (vasoconstriction) to preserve core temperature is also an established fact, detailed in publications such as the Journal of Applied Physiology (synthesis of physiological evidence). Regarding the extremities, experimental work such as that of Dr. Gordon Giesbrecht of the University of Manitoba (experimental physiological study) confirms that the hands and feet are major zones of heat exchange due to their high vascularization. Even if the common belief that we lose the majority of our heat solely through the extremities is nuanced today, protecting them remains a highly effective method for maintaining thermal comfort. Finally, muscle activation through movement and layering clothing are validated common-sense strategies for naturally stimulating the production of body heat.

the sources

No named source held this one up — that absence is part of the verdict.