Metabolic Heat Production

Metabolic heat production is the heat released from muscle metabolism in animals. Muscle function requires a steady supply of ATP. ATP is generated from the oxidation of metabolites in the mitochondria, a process which requires oxygen.

There are two ways of increasing body temperature through metabolic heat production: shivering and non-shivering thermogenesis. Shivering thermogenesis involves the hydrolysis of ATP in skeletal muscles to release kinetic and heat energy. Non-shivering thermogenesis involves brown fat, which contains specialised mitochondria that produce high amounts of heat energy when the fat is ‘burned’. Cold temperatures stimulate the release of hormones that activate brown fat, thus increasing metabolic rate and therefore bodily temperature.

The metabolic rate of an animal resting in the dark, not eating or digesting, is known as the basal metabolic rate (measured in J/s or Watts). An animal’s metabolic rate can be measured using a metabolic chamber to record oxygen consumption.