Cold-induced heat production preceding shivering

Area of Science:

• Human physiology
• Thermoregulation
• Metabolism

Background:

• Understanding individual thermoregulatory responses to cold is crucial for various physiological and clinical contexts.
• Shivering is a primary mechanism for heat production, but non-shivering thermogenesis also plays a role.
• Factors influencing the onset of shivering and the preceding thermogenic responses require further investigation.

Purpose of the Study:

• To investigate individual variations in heat production and body temperature during cold exposure before the onset of shivering.
• To determine the relationship between body composition, skin temperature, heat production, and the non-shivering interval (NSI).

Main Methods:

• Subjects (10 women, 7 men) were exposed to 15°C air after a 30-minute thermoneutral period.
• Heat production was measured using a ventilated hood.
• Body composition was assessed via underwater weighing and 2H dilution.
• Body temperatures were monitored using thermistors.

Main Results:

• Heat production increased and plateaued during cold exposure prior to shivering.
• Skin temperature decreased and did not plateau within the test period.
• The non-shivering interval (NSI) varied significantly (20-148 min) and was not linked to body composition.
• NSI was negatively correlated with skin temperature (r²=0.44, P=0.004).
• Skin temperature was positively correlated with heat production (r²=0.39, P=0.007).

Conclusions:

• Individuals with higher heat production during cold exposure maintained higher skin temperatures.
• A higher heat production was associated with a shorter non-shivering interval, independent of body composition.
• These findings highlight the interplay between metabolic heat production, skin temperature, and the timing of shivering onset.