Heat storage and body temperature during cooling and rewarming

Area of Science:

• Human Physiology
• Thermoregulation
• Calorimetry

Background:

• Accurate estimation of body heat storage is crucial for understanding thermoregulation.
• Burton's (1935) weighting coefficient 'a' relates changes in rectal temperature (Tre) and mean skin temperature (Tsk) to mean body temperature (delta Tb).

Purpose of the Study:

• To determine the reliability of Burton's coefficient 'a' in forced cooling and rewarming scenarios.
• To establish an accurate method for estimating changes in mean body temperature (delta Tb) and body heat storage.

Main Methods:

• Calorimetric experiments involving forced cooling (cold water, tubing suit) and rewarming.
• Measurement of rectal temperature (Tre) and mean skin temperature (Tsk).
• Calculation of change in body heat content (delta Hb) using direct and indirect calorimetry, incorporating individualized body fat content for specific heat values.

Main Results:

• The mean value of Burton's coefficient 'a' was 0.75 (0.01) across 119 determinations.
• A formula, 0.75 (delta Tre) + 0.25 (delta Tsk), accurately estimates delta Tb during forced cooling and rewarming.
• Individualized body heat content (delta Hb) ranged from -335 to -1600 kJ, with rewarming restoring heat content.

Conclusions:

• The formula 0.75 (delta Tre) + 0.25 (delta Tsk) provides a precise estimation of mean body temperature change (delta Tb).
• This method accurately quantifies body heat storage during forced thermoregulation challenges.
• The study validates the utility of Burton's coefficient in dynamic human thermoregulation.