Thermal and Physiological Responses of Basic Underwater Demolition/Seal (BUD/S)Students to a 5.5-Mile Open-Ocean Swim

摘要

Thermal stress can have a substantial negative impact on the performance of NavalSpecial Warfare (NSW) personnel during training and missions. This effect is especially evident during prolonged operations in cold water. Cold water is a particularly inhospitable environment. Heat conduction of water is 25 times that of air causing loss of body heat two to four times faster in water than in air at the same temperature. The rate of heat production by a swimmer and of body heat loss to the water are critical factors in core body temperature homeostasis. In cool and cold waters, the metabolic heat produced by swimming can be inadequate to counteract the large thermal drain imposed by the water. Although heat production is increased during exercise, heat loss is also increased. Reducing body heat loss to the water becomes critical for the prevention of hypothermia when metabolic heat production is less than heat loss.