THE NEW YORK TIMES – Our internal organs keep us warm when we’re sedentary, and our muscles become the primary source of heat when we’re active.
But there aren’t any organs or major muscles in hands and feet — just plenty of area for heat to escape and little insulation (or fat) to keep it in, said Stephen Cheung, a professor of kinesiology at Brock University in Ontario.
Instead, hands and feet stay warm thanks to a dense web of tiny vessels that circulate blood from the heart. These vessels narrow in the cold, as your body tries to reduce heat loss and redirect the warm blood toward your vital organs.
“Your brain says: ‘I can live without my hands and my feet. I can’t live without my heart, lungs, liver,’” Dr. Cheung said.
Some people can be more susceptible to cold hands and feet.
For example, women generally feel colder than men because the blood vessels in their hands and feet tend to constrict more rapidly in the cold, said Mike Tipton, a professor of human and applied physiology at the University of Portsmouth in England.
Children and people who are underweight also have less muscle mass and fat to generate and retain heat, he added.
Older people are at greater risk of having cold hands and feet as well, Dr. Tipton said, because their nerves and blood vessels tend to deteriorate over time.
When is this a medical problem?
Cold hands and feet can sometimes signal more serious issues.
For example, about 5 percent of Americans have Raynaud’s syndrome, in which spasms of the arteries in the hands and feet, usually caused by cold or stress, temporarily cut off blood flow.
This can cause the fingers and toes to change color, said Dr. Jessica Gordon, a rheumatologist …
