The muscle heat production after adaptation to cold.

The extent of heat production by muscular contractions in animals adapted to the cold was studied. Contractions of the skeletal muscles, diaphragm and heart muscle of cold-acclimatised animals were accompanied by greater heat production than was the case in the muscles of control animals. Such a change in the metabolism of muscular contractions is an important source of additional heat production in an animal adapted to cold. This phenomenon may well be of fundamental importance in bioenergetics.