Heat Transfer Model for Predicting Survival Time in Cold Water Immersion

Abstract

In the present paper a heat transfer (HT)

Body Composition of Cold-Water Swimmers: The San Francisco Polar Bear Swim Study

“…Increased % fat has been associated with decreased cooling and increased survival in cold water [1,7,8,[16][17][18][19]. Although % fat values in our study were not generally elevated, average % fat values in our study were also not substantially decreased, and no subject was underweight by BMI criteria (BMI<18.5 kg/m 2 ) [9].…”

“…Review of prior work [8,[16][17][18][19] suggests that on the basis of gross body composition, our subjects overall were not substantially protected from immersion hypothermia when compared to average Americans. Perhaps contrary to common perception, repeated exposure to cold water has not been shown conclusively to confer a substantial ability to conserve core heat [8,17,18].…”

“…Increased overall body size (as reflected by increases in BMI and decreases in surface/volume ratio) like increased % fat, has been associated with decreased cooling and increased survival or performance in cold water [2,4,12,[16][17][18][19]. Surface/volume ratio has been used previously to assess overall size and general body morphology, with larger individuals having smaller ratios [2,12,[17][18][19].…”

“…Such heat production has limits [8,[16][17][18], but may have been temporarily advantageous in the conditions and relatively short immersion times we describe. Access to warm showers and saunas also may have contributed to the success of some individuals, but all individuals, even those with increased size, faced time limits that depended on the water temperature and conditions on any given day [1,4,8,[16][17][18][19].…”

“…Perhaps contrary to common perception, repeated exposure to cold water has not been shown conclusively to confer a substantial ability to conserve core heat [8,17,18]. Rather, as outlined above, body composition variables, particularly % fat and overall body size, are key determinants of core cooling rate in cold water [1,2,4,8,[16][17][18][19]. Thus, with measured body composition variables that were grossly similar to average Americans, our subjects as a group would not be expected to have substantially better direct physical protection from core hypothermia.…”