Thermoregulatory responses to air temperature of −5 °C at different wind speeds: significance of strong wind in a mild cold environment

TL;DR

This study examines how wind speed affects body temperature and comfort in mild cold weather, showing that winter clothing protects core temperature but not extremities like hands.

Contribution

The study provides new insights into thermoregulatory responses to wind in mild cold environments, focusing on clothing insulation and individual body characteristics.

Findings

Winter clothing (2.1 clo) maintains core temperature in wind chill down to −12 °C.

Peripheral skin temperatures, especially fingers, decrease significantly with higher wind speeds.

Overweight individuals shiver less and have larger body surface areas correlating with greater cold sensitivity.

Abstract

Air temperature that is considered as cold varies according to individuals. Urban people who live in temperate climates are accustomed to mild cold with varying wind speeds, but relatively few studies have examined the effects of wind speed in mild cold on individuals wearing winter clothing, especially compared to studies conducted in severe cold environments. We examined thermoregulatory responses to varying wind speeds in mild cold, considering anthropometric characteristics of individuals.

Ten healthy males (23.9 ± 3.3 years in age, 175.8 ± 4.9 cm in height, 74.4 ± 7.0 kg in body weight) participated in the following four wind conditions (0, 2, 4.5, and 7 m·s−1) at an air temperature of −5 °C (wind chill temperature: −5 to approximately −12 °C). Subjects wore winter clothing (IT, 2.1 clo), and every trial consisted of 80 min (10-min rest, 60-min walking, and 10-min recovery).

Rectal and gastrointestinal temperatures remained stable across all wind conditions, suggesting sufficient insulation from the winter clothing. However, peripheral skin temperatures decreased significantly with higher wind speeds (all Ps < 0.05), with finger temperature averaging 12.7 °C at 7 m·s−1. Overweight subjects showed less frequent shivering than normal-weight subjects. Both body surface area (BSA) and body mass index (BMI) were negatively correlated with overall thermal comfort and positively correlated with shivering frequency (all Ps < 0.05). BSA was also negatively correlated with toe temperature (P = 0.001).

While typical winter clothing (2.1 clo) effectively maintains core temperature in wind chill conditions down to −12 °C, extremities, particularly the hands, require better insulation. Peripheral skin temperatures and thermal comfort provide reliable indicators for assessing cold stress. Morphological properties of the body also influenced cold responses, with overweight individuals exhibiting less frequent shivering and larger body surface areas correlating with greater cold sensitivity. These findings offer insights into optimizing winter clothing design to improve comfort and safety in windy conditions in mild cold.

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