Sex difference in cold perception and shivering onset upon gradual cold exposure

Area of Science:

• Human Physiology
• Thermoregulation
• Sex Differences in Physiology

Background:

• Humans maintain thermal balance by reducing heat loss and increasing heat production, with shivering being a rapid heat generation mechanism.
• Previous research suggests women prefer warmer environments and report lower comfort levels than men in identical thermal conditions.

Purpose of the Study:

• To investigate if there is a difference in the experimental temperature (TE) at which men and women initiate shivering.
• To determine if sex influences the threshold for cold-induced thermogenesis.

Main Methods:

• Twenty male and 23 female volunteers participated in a controlled cooling protocol using the Blanketrol® III device.
• Environmental temperature was gradually decreased from 24°C, with shivering onset detected via electromyogram (EMG) or a minimum temperature of 9°C.

Main Results:

• Women initiated shivering at a significantly higher experimental temperature (11.3°C ± 1.8°C) compared to men (9.6°C ± 1.8°C; P = 0.003).
• Women also reported feeling cold at a higher experimental temperature (18.3°C ± 3.0°C) than men (14.6°C ± 2.6°C; P < 0.001).

Conclusions:

• This study demonstrates a clear sex difference in the physiological response to cold exposure, with women initiating shivering earlier than men.
• These findings underscore the need to consider sex as a critical factor in the design and interpretation of physiological studies involving cold exposure and thermal regulation.