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Rheological modelling of physiological variables during temperature variations at rest
1Hoger Institut voor Lichamelijke Opvoeding, Vrije Universiteit Brussel, Belgium.
International Journal of Biometeorology
|August 1, 1990
Summary
Cold exposure affects physiological responses, increasing oxygen consumption and core temperature while lowering peripheral temperature. The human body
Area of Science:
- Human Physiology
- Environmental Medicine
- Thermoregulation
Background:
- Understanding human physiological responses to cold stress is crucial for various occupational and survival scenarios.
- Previous research has explored thermoregulatory mechanisms, but the dynamic adaptation kinetics during cold exposure and recovery require further investigation.
Purpose of the Study:
- To investigate the time-dependent evolution of cardio-respiratory variables, blood pressure, and body temperature during acute cold exposure and passive recovery.
- To analyze the kinetic adaptation of physiological responses using a rheological model and compare adaptation rates between cooling and rewarming phases.
Main Methods:
- Six healthy males were exposed to a cold environment (0°C) for 30 minutes followed by a 60-minute recovery period (20°C) in a semi-nude state.
- Continuous monitoring of heart rate (HR), oxygen consumption (VO2), carbon dioxide production (VCO2), ventilation (Ve), core temperature (Tre), and peripheral temperatures.
- Application of a Kelvin-Voigt rheological model to assess the dynamic adaptation of physiological variables.
Main Results:
- Cold exposure did not alter heart rate but significantly increased VO2, VCO2, Ve, and core temperature (Tre), while peripheral temperatures decreased.
- Adaptation rates for HR, blood pressure, and skin temperatures were faster during cold exposure than during the recovery period.
- Respiratory adjustments (VO2, VCO2, Ve) exhibited an inverse kinetic evolution compared to cardiovascular and peripheral temperature responses.
Conclusions:
- The human body's physiological response to cold stress does not perfectly align with a simple viscoelastic model, indicating complex adaptive mechanisms.
- Cold exposure triggers rapid cardiovascular and peripheral thermoregulation, while respiratory systems show delayed adaptation during rewarming.
- Mechanisms aimed at preserving core homeothermy and increasing oxygen supply during cold stress lead to increased overall energy loss.