Physiological and perceptual responses to temperature step changes between cold and hot environments

Area of Science:

• Environmental physiology
• Occupational health
• Thermal comfort research

Background:

• Workers in cold environments face abrupt temperature changes, impacting their thermal responses.
• Understanding physiological and perceptual reactions to rapid temperature shifts is vital for occupational safety.

Purpose of the Study:

• To investigate the effects of temperature step magnitude and direction on human thermal responses.
• To analyze physiological, perceptual, and self-reported health changes during simulated winter temperature fluctuations.

Main Methods:

• Eleven sedentary participants underwent three temperature step protocols (S20, S30, S40) with distinct phases.
• Physiological data (heart rate, blood pressure, skin temperature, sweating), thermal perception, and health symptoms were recorded.

Main Results:

• Temperature up-steps delayed skin temperature stabilization and sweating; heart rate decreased with increasing step magnitude.
• Temperature down-steps led from comfort to cold strain, with blood pressure rising proportionally to step magnitude.
• Asymmetrical thermal responses were observed between up and down temperature steps, diminishing with larger step magnitudes.

Conclusions:

• Temperature step magnitude and direction significantly influence human thermal responses.
• Thermal perceptions react faster than physiological changes, while health symptoms show a delayed response.
• Findings provide essential data for understanding occupational thermal stress in dynamic winter conditions.