Shivering is a means of physiological heat production. It is the trembling of the individual, or fibrillation of a muscle, that is cold. It results from somatic activation of skeletal muscles which asynchronously contract. It is preceded by a phase of increased muscle tone.
Shivering is normally involuntary, but it can be suppressed by higher cortical input. This behaviour has to be learned but is valuable to divers who need to retain fine motor skills in a cold environment.
Elderly people have a poor shivering response. Hence, their body temperature tends to drop faster than in the young.
Last reviewed 01/2018