Metabolic and thermal responses of women during cooling in water

Kollias, James; Barlett, L.; Bergsteinova, V.; Skinner, J. S.; Buskirk, E. R.; Nicholas, W. Channing

doi:10.1152/jappl.1974.36.5.577

Cited by 39 publications

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“…Numerous studies have suggested a relationship between core cooling and A d /mass (29,30,32), whereby a larger A d /mass (i.e., a smaller size) leads to greater decreases in T c during cold stress. Several studies reported that women having higher A d /mass but similar adiposity cooled faster compared with men (29,30).…”

Section: Discussionmentioning

confidence: 99%

Responses to mild cold stress are predicted by different individual characteristics in young and older subjects

DeGroot¹,

Havenith²,

Kenney

2006

Journal of Applied Physiology

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ney. Responses to mild cold stress are predicted by different individual characteristics in young and older subjects. J Appl Physiol 101: 1607-1615, 2006. First published August 3, 2006 doi:10.1152/japplphysiol.00717.2006.-Older individuals' ability to maintain core temperature during cold stress is impaired; however, the relative importance of individual characteristics that influence this response are unknown. The purpose of this study was to determine the relative influence of individual characteristics on core temperature and tissue insulation (I t) during mild cold stress. Forty-two young (23 Ϯ 1 yr, range 18 -30 yr) and 46 older (71 Ϯ 1 yr, range 65-89 yr) subjects, varying widely in muscularity, adiposity, and body size, underwent a transient cooling protocol during which esophageal temperature (T es) was measured continuously and I t was calculated using standard equations. Multipleregression analyses were performed to determine predictors of T es and It, and standardized regression coefficients were analyzed to determine the relative influence of each predictor. Candidate predictors included age, sex, weight, body surface area, body surface area-to-mass ratio, sum of skinfolds, percent fat, appendicular skeletal muscle mass, and thyroid hormone concentrations (triiodothyronine, thyronine). The sum of skinfolds explained 67% (P Ͻ 0.01) of the T es variance in young subjects vs. 2% (P ϭ 0.30) in older subjects. Conversely, appendicular skeletal muscle mass explained a greater portion of the variance in older subjects for both T es (older: 28%, P Ͻ 0.01; young: 8%, not significant) and It (older: 46%, P Ͻ 0.01; young: 17%, P Ͻ 0.01). The Tes residual variance was considerably larger in older subjects (59 -72% vs. 14 -42% in young subjects), possibly due to varying rates of physiological aging. These results suggest that the relative influence of individual characteristics changes with aging. core temperature; tissue insulation; body composition; aging EPIDEMIOLOGICAL EVIDENCE SUGGESTS that older individuals are more susceptible to hypothermia than young individuals, with Ͼ50% of deaths due to hypothermia occurring in those aged Ͼ65 yr, an age cohort comprising only ϳ12% of the US population (8). Cross-sectional studies confirm that aged individuals have a relative inability to maintain core temperature

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Section: Discussionmentioning

confidence: 99%

Responses to mild cold stress are predicted by different individual characteristics in young and older subjects

DeGroot¹,

Havenith²,

Kenney

2006

Journal of Applied Physiology

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“…By virtue of its lower water content, fat tissue has a lower thermal conductivity than lean tissue (Cohen, 1977;Cooper and Trezek, 1971) and, hence, when fat tissue is distributed in a continuous subcutaneous layer (such as the layer of blubber in pinnipeds and cetaceans) it may provide substantial thermal insulative benefits. Studies of humans immersed in cool water (15-20°C) show that individuals who have greater adiposity cool down more slowly than leaner individuals and do not need to elevate their metabolic rate as much to defend this slower cooling rate (Cannon and Keatinge, 1960;Buskirk et al, 1963;Kollias et al, 1974;Keatinge, 1978;Hayward and Keatinge, 1981;Tikuisis et al, 1988;GlickmannWeiss et al, 1991). These studies indicate that obesity in humans also provides an insulative advantage.…”

Section: Introductionmentioning

confidence: 99%

The evolution of body fatness: trading off disease and predation risk

Speakman

2018

Journal of Experimental Biology

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Human obesity has a large genetic component, yet has many serious negative consequences. How this state of affairs has evolved has generated wide debate. The thrifty gene hypothesis was the first attempt to explain obesity as a consequence of adaptive responses to an ancient environment that in modern society become disadvantageous. The idea is that genes (or more precisely, alleles) predisposing to obesity may have been selected for by repeated exposure to famines. However, this idea has many flaws: for instance, selection of the supposed magnitude over the duration of human evolution would fix any thrifty alleles (famines kill the old and young, not the obese) and there is no evidence that hunter-gatherer populations become obese between famines. An alternative idea (called thrifty late) is that selection in famines has only happened since the agricultural revolution. However, this is inconsistent with the absence of strong signatures of selection at single nucleotide polymorphisms linked to obesity. In parallel to discussions about the origin of obesity, there has been much debate regarding the regulation of body weight. There are three basic models: the setpoint, settling point and dual-intervention point models. Selection might act against low and high levels of adiposity because food unpredictability and the risk of starvation selects against low adiposity whereas the risk of predation selects against high adiposity. Although evidence for the latter is quite strong, evidence for the former is relatively weak. The release from predation ∼2-million years ago is suggested to have led to the upper intervention point drifting in evolutionary time, leading to the modern distribution of obesity: the drifty gene hypothesis. Recent critiques of the dual-intervention point/ drifty gene idea are flawed and inconsistent with known aspects of energy balance physiology. Here, I present a new formulation of the dual-intervention point model. This model includes the novel suggestion that food unpredictability and starvation are insignificant factors driving fat storage, and that the main force driving up fat storage is the risk of disease and the need to survive periods of pathogen-induced anorexia. This model shows why two independent intervention points are more likely to evolve than a single set point. The molecular basis of the lower intervention point is likely based around the leptin pathway signalling. Determining the molecular basis of the upper intervention point is a crucial key target for future obesity research. A potential definitive test to separate the different models is also described.

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“…Regarding the CCR, many studies have demonstrated that there is a significant difference in thermoregulatory responses between groups with different morphological factors such as skinfold thickness, body size, and body weight during cold water immersion, primarily because of differences in total body thermal insulation (Keatinge, 1960;Kollias et al, 1974;Toner et al, 1986;Mekjavic et al, 1987;White et al, 1992). In the present study, all subjects were cooled in the same manner with the water-perfused suit.…”

Section: Figmentioning

confidence: 99%

Individual Variability in the Core Interthreshold Zone as Related to Body Physique, Somatotype, and Physical Constitution

Kakitsuba

Mekjavic

Katsuura

2009

J Physiol Anthropol

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For evaluating the effect of body physique, somatotype, and physical constitution on individual variability in the core interthreshold zone (CIZ), data from 22 healthy young Japanese male subjects were examined. The experiment was carried out in a climatic chamber in which air temperature was maintained at 20-24°C. The subjects' body physique and the maximum work load were measured. Somatotype was predicted from the Heath-Carter Somatotype method. In addition, factors reflecting physical constitution, for example, susceptibility to heat and cold, and quality of sleep were obtained by questionnaire. The subjects wore a water-perfused suit which was perfused with water at a temperature of 25°C and at a rate of 600 cc/min, and exercised on an ergometer at 50% of their maximum work rate for 10-15 min until their sweating rate increased. They then remained continuously seated without exercise until shivering increased. Rectal temperature (T re ) and skin temperatures at four sites were monitored by thermistors, and sweating rate was measured at the forehead with a sweat rate monitor. Oxygen uptake was monitored with a gas analyzer. The results showed individual variability in the CIZ. According to the reciprocal crossinhibition (RCI) theory, thermoafferent information from peripheral and core sensors is activated by T re , mean skin temperature (T sk ), and their changes. Since T sk was relatively unchanged, the data were selected to eliminate the influence of the core cooling rate on the sensor-to-effector pathway before RCI, and the relationship between the CIZ and the various factors was then analyzed. The results revealed that susceptibility to heat showed a good correlation with the CIZ, indicating that individual awareness of heat may change the CIZ due to thermoregulatory behavior.

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Metabolic and thermal responses of women during cooling in water

Cited by 39 publications

References 0 publications

Responses to mild cold stress are predicted by different individual characteristics in young and older subjects

Responses to mild cold stress are predicted by different individual characteristics in young and older subjects

The evolution of body fatness: trading off disease and predation risk

Individual Variability in the Core Interthreshold Zone as Related to Body Physique, Somatotype, and Physical Constitution

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