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Thermoregulation in Winter Swimmers and Physiological Significance of Human Catecholamine Thermogenesis

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Abstract

Thermoregulation in control subjects and cold-adapted winter swimmers was examined during 1 h of cold water immersion (13 C). It was found that the thermoregulatory functions of winter swimmers differ from those of non-cold-adapted subjects. As evident from the relationship between rectal temperature and the magnitude of cold thermogenesis, in controls a significant part of cold thermogenesis during the early phase of cooling was induced by changes in peripheral temperature input, while in the late phase of cooling it was the central temperature input which was mainly engaged in induction of cold thermogenesis. In winter swimmers the magnitude of cold thermogenesis was solely related to changes in rectal temperature, indicating the predominance of the central temperature input in activation of heat production mechanisms. The thermoregulatory threshold for induction of cold thermogenesis was lowered (by 0.34 C), but the apparent hypothalamic thermosensitivity was the same as in non-cold-adapted subjects. These differences are indicative of adaptation of thermoregulatory control centres. Additionally, the activity of thermoregulatory effectors was also changed. Shivering was induced later during cooling (after 40 min) in winter swimmers than in controls, which suggests an important participation of non-shivering thermogenesis in the early thermogenic response. Winter swimmers also showed bradycardia and a greater reduction in plasma volume during cooling. The data indirectly indicate restriction of heat loss from the body. Only a non-significant increase in quantity of subcutaneous fat was observed in winter swimmers. Thus, winter swimmers were able to survive a significantly greater temperature gradient between body and environment than non-cold-adapted subjects by modifying the sensory functions of hypothalamic thermoregulatory centres to lower heat loss and produce less heat during cold exposure. Additionally, the capacity of the total cold thermogenesis due to potentiation of non-shivering heat production was also increased. Heat produced due to thermogenic action of adrenaline may represent more than a quarter of the total cold thermogenesis. In conclusion, the data suggest that winter swimmers exhibit metabolic, hypothermic and insulative types of cold adaptation.

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... Optimal thermoregulatory functioning, which is affected by adaptation to chronic cold exposure, is of critical importance for the survival, health and well-being of humans who are exposed to occupational and/or recreational extreme-cold conditions. It has been well demonstrated that successful whole-body adaptation to cold in humans can be expressed differently, as indicated by the development of the metabolic (as evidenced by no change in rectal temperature (T re ), whereas skin temperature (T sk ) and metabolic heat production (MHP) increases), hypothermic (as evidenced by no change in T sk , whereas T re and MHP decreases) or insulative (as evidenced by no change in T re and MHP, whereas T sk decreases) type of acclimation (induced experimentally) or acclimatization (induced naturally) [19,56,4,53,47,24,29]. The existence of insulative-hypothermic [41,56,24,29] or metabolicinsulative [4,29] subtypes is sometimes evident as well. ...
... The existence of insulative-hypothermic [41,56,24,29] or metabolicinsulative [4,29] subtypes is sometimes evident as well. Nevertheless, it has been shown that all three possible types of cold adaptation were present in winter swimmers [27,53] and female pearl divers (AMA) from Korea [21]. Both groups adapted to acute cold by swimming or diving outdoors regularly during winter for several years; in those conditions, the water temperature decreases down to 2uC or 10uC, respectively. ...
... It has been shown that, in cold-adapted winter swimmers, the thermoregulatory threshold for induction of cold thermogenesis was 0.34uC (T re ) lower than that observed in non-adapted individuals [53]. In the CA-17 session, the subjects were immersed in cold water for about 25 min longer than they were in the CA-16 session. ...
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The time course of physiological and psychological markers during cold acclimation (CA) was explored. The experiment included 17 controlled (i.e., until the rectal temperature reached 35.5°C or 170 min had elapsed; for the CA-17 session, the subjects (n = 14) were immersed in water for the same amount of time as that used in the CA-1 session) head-out water immersions at a temperature of 14°C over 20 days. The data obtained in this study suggest that the subjects exhibited a thermoregulatory shift from peripheral-to-central to solely central input thermoregulation, as well as from shivering to non-shivering thermogenesis throughout the CA. In the first six CA sessions, a hypothermic type of acclimation was found; further CA (CA-7 to CA-16) led to a transitional shift to a hypothermic-insulative type of acclimation. Interestingly, when the subjects were immersed in water for the same time as that used in the CA-1 session (CA-17), the CA led to a hypothermic type of acclimation. The presence of a metabolic type of thermogenesis was evident only under thermoneutral conditions. Cold-water immersion decreased the concentration of cold-stress markers, reduced the activity of the innate immune system, suppressed specific immunity to a lesser degree and yielded less discomfort and cold sensation. We found a negative correlation between body mass index and Δ metabolic heat production before and after CA.
... When the temperature decreases suddenly, an increase in the levels of stress hormones is observed [2,13]. To prevent hypothermia, the organism produces heat by inducing shivering and increasing shivering thermogenesis [14]. Muscle shivering leads to the deterioration of muscle coordination and fatigue, which restrict the ability for physical effort. ...
... It is important to avoid a decrease in the body temperature below 32°C and to prevent arrhythmia, while in case of danger; the person should be taken out of water immediately [16]. Despite the existing risks, cold water may apparently bring considerable benefits, since the people who regularly practise bathing in ice-cold water are more resistant to cold [14]. ...
... In this study, the group of winter swimmers was composed of people who were passionate about bathing in ice-cold water and regularly practised this activity (once a week). It was observed that those people had a higher content of fat in their bodies, which may constitute a form of protection against heat loss and indicates that the body heat derived from the processes involved in non-shivering thermogenesis [2,14]. Human organism, in response to temperature reduction, employs the mechanism of adaptive thermogenesis which involves energy dissipation in the form of heat [21]. ...
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INTRODUCTION. Winter swimming is a form of physical recreation that involves bathing in cold water during winter. The aim of the study was to analyse the body composition in people who regularly take baths in ice-cold water. MATERIAL AND METHODS. The study included 20 men. Half of them (mean age 27.7 ± 7.1 years) were regularly taking baths in cold water (winter swimmers) at least for a year, while the rest (mean age 27.0 ± 4.0 years) had never performed such a treatment (controls). In each subject, a body composition profile was evaluated, including: body mass index (BMI), body mass (BM kg), body fat percentage (BF%), fat mass (FM kg), fat-free mass (FFM kg), the fat mass-to-fat-free mass ratio (FM/FFM%), total body water (TBW% and TBW kg) and muscle mass (MM% and MM kg). The measurements were taken using the body composition analyser Tanita – BC 418 MA, which employed the BIA (Bioelectrical Impedance Analysis) method, and via anthropometric measurements. RESULTS. The BMI value among the winter swimmers was significantly higher than among people not practising winter swimming. Moreover, in the winter swimmers, higher BF % and FM/FFM% ratio values, as well as a lower MM% value were found, as compared with the controls. CONCLUSIONS. The obtained results suggest that the choice of bathing in cold water as a form of recreation may depend on the content of the adipose tissue. The tissue constitutes an insulating layer which efficiently protects overweight people from an excessive heat loss.
... Reakcją indukującą proces adaptacyjny u "morsów" podczas przebywania w zimnej wodzie jest zmniejszenie przepływu krwi przez skórę, co zwiększa jej wartość termoizolacyjną (37,38). Adaptacja ta obejmuje zmniejszenie pojemności minutowej serca i częstości akcji serca jak również zwiększonego zwężenia naczyń w skórze (39,40). Stwierdzono, iż u pływających w zimie metabolizm zwiększa się zarówno po zanurzeniu w wodzie, jak i po zakończeniu pływania. ...
... Stwierdzono, iż u pływających w zimie metabolizm zwiększa się zarówno po zanurzeniu w wodzie, jak i po zakończeniu pływania. Jest to spowodowane pobudzeniem centralnego ośrodka termoregulacji w podwzgórzu, który jest mniej wrażliwy na informacje pochodzące z termoreceptorów skóry (40). Z tego też powodu termogeneza bezdrżeniowa jest głównym mechanizmem wytwarzania energii cieplnej u "morsów" w ciągu pierwszej godziny od zanurzenia w zimnej wodzie (38,40). ...
... Jest to spowodowane pobudzeniem centralnego ośrodka termoregulacji w podwzgórzu, który jest mniej wrażliwy na informacje pochodzące z termoreceptorów skóry (40). Z tego też powodu termogeneza bezdrżeniowa jest głównym mechanizmem wytwarzania energii cieplnej u "morsów" w ciągu pierwszej godziny od zanurzenia w zimnej wodzie (38,40). Należy w tym miejscu podkreślić, że mechanizmy termogenezy bezdrżeniowej u pływających w zimie nie są do końca zbadane. ...
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streszczenie Termoregulacja odgrywa ważną role w utrzymywaniu homeostazy w czasie odpoczynku i wysiłku. W niskiej temperaturze termoreceptory reagując na zmianę temperatury stymulują ośrodek termoregulacji zlokalizowany w podwzgórzu, uruchamiając mechanizmy oszczędzania i wytwarzania ciepła. W czasie ekspozycji na bardzo niską temperaturę, szczególnie w środowisku wodnym, metaboliczne wytwarzanie ciepła przez organizm nie jest w stanie wyrównać jego utraty i może dojść do hipotermii. Jej mechanizmy w środowisku w wodnym, przeciwnie niż na powietrzu związane są z utratą ciepła przez przewodzenie. Podczas przebywania w zimnej wodzie dochodzi do przyspieszonej utraty ciepła ze skóry, połączo-ne ze skurczem naczyń obwodowych, a także z odpływem krwi ze skóry i warstwy podskórnej, co prowadzi do spadku temperatury skórnej. Temperatura wody o wartości 18°C może być uważana za wartość graniczną niskich temperatur-poniżej tego poziomu temperatura wewnętrzna obniża się szybciej w trakcie pływania niż w spoczynku. Zanurzenie głowy w zimnej wodzie, prowadzi do nieproporcjonalnie dużego spadku temperatury wewnętrznej. Przebywanie w środowisku wodnym o niskiej temperaturze może u niezaadaptowanych ludzi prowadzić do poważnego zagrożenia zdrowia, podczas gdy u osobników regularnie pływających w zimie tzw. morsów, rozwija się tolerancja na zimno. Co więcej te mechanizmy adaptacyjne mogą prowadzić do zjawiska "hartowania"-zapobiegania wielu innym chorobom. Słowa kluczowe: termoregulacja w wodzie, układ krążenia, układ współczulny, mechanizm, termoregulacji "morsów" Abstract: The thermoregulation play important roles in maintaining homeostasis during rest and physical exercise. A low temperature stimulates thermoreceptors to provide feedback to the hypothalamus to activate the mechanisms that conserving body heat and increasing heat production. In cold water these mechanisms are often not adequate and exercising could leads to hypothermia which is usually attributed to convective and conductive heat loss from the body. Heat loss by convection from the body surface is a major pathway but in water, conduction is the most important factor. Head submersion increases the rate of core cooling disproportionally more than the relative increase in total heat loss. Cold water exposure immediately increases the rate of heat loss from the skin, which causes a decrease in skin temperature. If the water temperature fall below 18°C temperature exercise in fact could increases the rate of heat loss. Immersion in cold water in unaccustomed persons may lead to detrimental consequences, while in regular winter swimmers, adaptive physiologic mechanisms increase tolerance to cold. Furthermore, these mechanisms may prevent the occurrence of a wide variety of diseases.
... During repeated exposure to cold stress, mechanisms of re- sistance are replaced by mechanisms of adaptation. Repeated ex- posure to cold induces physiological changes that have been documented in studies in humans, both in the natural environ- ment ( Vybiral et al., 2000) and in laboratory conditions ( Sramek et al., 2000). For a long time, there were even doubts about whether metabolic adaptation to cold existed in humans. ...
... For a long time, there were even doubts about whether metabolic adaptation to cold existed in humans. We ( Vybiral et al., 2000) have shown that cold adaptation in winter swimmers consists of metabolic, hypothermic and insulative types of cold adaptation, as has also been previously described by Bittel (Bittel, 1992). ...
... Shivering puts further demands on the cardiovascular system and together these factors can support atherosclerotic plaque disrup- tion and subsequent thrombus formation. It seems plausible that the delayed onset of shivering in cold-adapted subjects ( Vybiral et al., 2000) may decrease this risk connected with cold exposure. ...
... Catecholamines like dopamine, adrenaline and noradrenaline may be auto-oxidized and form superoxide anion, which is subsequently capable of oxidizing more the originating compound thus setting up a complex free-radical chain reaction (Kruk and K"adna, 1998). The increase of some catecholamines after whole-body exposure to cold water was observed by some authors (Leppäluoto et al., 2008;Vybiral et al., 2000). Huttunen et al. (2001) postulated that attenuation of the catecholamine responses to cold water observed during winter swimming season may be an element of adaptation to Table 5 Heart rate measured before, during and after exposure to cold water in form of winter swimming (WS) in people regularly taking baths in freezing water (regular winter swimmers) and in those who practiced it for the first time (novice winter swimmers). ...
... The authors imply that physical training allows a more efficient activation of antioxidant mechanism under thermal stress thus it may be a kind of adaptation of organism to cold exposure. The mechanisms responsible for cold adaptation in humans have been studied for years, but still are not fully understood (Vybiral et al., 2000). In presented paper no statistically significant differences in basal activity of antioxidant enzymes or in concentration of lipid peroxidation products were observed between regular and inexperienced winter swimmers. ...
... Wśród czyn ni ków na tu ral nych, wo da ze wzglę du na wy so ki współ czyn nik prze wod no ści ciepl nej jest jed nym z naj lep szych wy mien ni ków cie pła. Wią że się to z sze re giem re ak cji ter mo re gu la cyj nych w or ga ni zmie, któ re to wa rzy szą ką pie lom w zim nej wo dzie [8] . Do fizjo lo gicz nych re ak cji chro nią cych przed utra tą cie pła w pierw szej fa zie na le ży m.in. ...
... Among the natural factors, water, due to the high thermoregulatory ratio, is one of the best heat ex chan gers. This is connected with a series of thermo regulatory reactions in the body, associated with bath ing in cold water [8] . The physiological respon ses protecting the body from heat loss during the first phase include: blood vessel contractions, elevation of arterial blood pressure, heart rate slowing, in crease in muscle tone and urine excretion, and slow ing of the metabolic rate [9]. ...
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of adaptive responses in the body, especially in the circulatory system. The aim of this study was to determine the effect of bathing in cold water on blood morphology. Material and methods. The sample was composed of 30 people: fourteen winter swimmers regularly bathing in cold water, and sixteen amateurs who were not subjected to such treatments before. On the day of the experiment all subjects spent 3 minutes in water at the temperature of 0°C with an ambient temperature of -4°C. Blood samples were taken before exposure to low temperatures (control) as well as 5 and 30 min after bathing in cold water. The basic parameters of peripheral blood: RBC, HGB, HCT, MCV, MCH, MCHC, WBC and PLT were estimated using an automatic hematological analyzer. Results. The study showed a slight increase in mean corpuscular hemoglobin concen - tration (MCHC) in winter swimmers and lower mean corpuscular volume (MCV) in ama - teurs 30 min after bathing in cold water vs. the control study. Comparison of the studied groups showed a higher mean MCV value in winter swimmers 5 min after cold bath, and a higher leukocyte count in amateurs 30 min after bathing in ice-cold water. Conclusions. Bathing in cold water affects some blood morphological parameters which may result from changes in the circulating blood in exposure to low ambient tem - peratures. A larger number of leukocytes observed in amateurs may prove an intensified immune response after cooling of the body.
... In addition, whole body skin surface cooling at rest, with cold air exposure, or cold water immersion, decreases the plasma volume (PV) (Deuster et al. 1989;Young et al. 1987) via cold-induced diuresis (Rochelle and Horvath 1978) or fluid shift from intravascular to interstitial spaces by vasoconstriction in hypothermia (Nose 1982). Indeed, Vybiral et al. (2000) reported that cold water immersion at 13 °C for 1 h increased plasma noradrenaline concentration approximately fourfold and also decreased PV approximately 15% in swimmers. Notably, increased sympathetic nerve activity has been known to enhance glycolysis in the muscle (Stob et al. 2007). ...
... Additionally, there were no differences in total urinary volume and weight loss across the trials. Previous studies showed decreases in PV when whole body cooling with cool or cold water immersion was used; therefore, the effects would be associated with skin surface cooling and with the increased hydrostatic pressure on the body associated with water immersion (Vybiral et al. 2000). Thus, a reduction in PV by skin surface cooling with a water-perfusion suit in the present study would be mild compared with that of the previous study. ...
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Purpose: We assessed whether plasma lactate accumulation increased and the lactate threshold (LT) declined when the skin temperature was lowered by whole body skin surface cooling before exercise in cool, but not temperate, conditions, and whether the lowered LT was associated with sympathetic activation or lowered plasma volume (PV) by cold-induced diuresis. Methods: Ten healthy subjects performed a graded maximal cycling exercise after pre-conditioning under three different conditions for 60 min. Ambient temperature (using an artificial climatic chamber) and water temperature in a water-perfusion suit controlled at 25 and 34 °C in temperate-neutral (Temp-Neut); 25 and 10 °C in temperate-cool (Temp-Cool); and at 10 and 10 °C in cool-cool (Cool-Cool) conditions, respectively. Esophageal (Tes) and skin temperatures were measured; plasma lactate ([Lac]p) and noradrenaline concentrations ([Norad]p), and relative change in PV (%ΔPV) were determined before and after pre-conditioning and during exercise, and LT was determined. Results: After pre-conditioning, Tes was not different among trials, whereas the mean skin temperature was lower in Cool-Cool and Temp-Cool than in Temp-Neut (P < 0.001). During exercise, [Lac]p and [Norad]p were higher (P = 0.009 and P < 0.001, respectively) and LT was lower (P = 0.013) in Cool-Cool than in the other trials. The %ΔPV was not different among trials. LT was correlated with [Norad]p during exercise (R = 0.50, P = 0.005). Conclusions: Whole body skin surface cooling before exercise increases lactate accumulation and decreases LT with sympathetic activation when exercise is performed in a cool, but not in a temperate, environment.
... CWS have been reported to possess better ability to cope with oxidative stress as a result of repeated exposure to cold and subsequent cold adaptation (7). To maintain core body temperature during cold exposure, both shivering and nonshivering components of thermogenesis are required (7,(10)(11)(12)(13). Vybiral et al. observed the later onset of the shivering process in winter swimmers than in control subjects, and suggested nonshivering thermogenesis to be a significant part of the cold response in CWS (10)(11)(12). ...
... To maintain core body temperature during cold exposure, both shivering and nonshivering components of thermogenesis are required (7,(10)(11)(12)(13). Vybiral et al. observed the later onset of the shivering process in winter swimmers than in control subjects, and suggested nonshivering thermogenesis to be a significant part of the cold response in CWS (10)(11)(12). The involvement of brown adipose tissue (BAT) in the response to cold has been demonstrated in animal and human studies (14)(15)(16). ...
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It has been proposed that regular cold swimming is associated with health benefits. However, the effect of cold adaptation on particular cardiovascular risk factors, within a single swimming season, remains unknown. Our aim was to evaluate the impact of cold water swimming on the seasonal changes in lipid profile and on apolipoprotein and homocysteine concentration in 34 cold water swimmers (CWS) aged 48 - 68 years. Blood samples were collected at the beginning (October), the middle (January), and the end (April) of the swimming season. Body mass (BM), total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides (TG), ApoB/ApoA-I ratio, and homocysteine concentrations were evaluated. In October, female CWS showed lower BM (P = 0.01), TG concentrations (P = 0.03), and ApoB/ApoA-I ratios (P = 0.008), and higher HDL (P = 0.01) than in men. Similar trends in BM (P = 0.002), HDL (P = 0.0006), and ApoB/ApoA-I ratio (P = 0.01) were seen in January, and for BM (P = 0.002), TG (P = 0.005), HDL (P = 0.003), and ApoB/ApoA-I (P = 0.01) in April. A decrease in TG concentration between January and April (P = 0.05), lower homocysteine concentration between October and January (P = 0.01), and between October and April (P = 0.001) were documented in CWS. A strong drop in homocysteine concentration was observed in female versus male CWS (P = 0.001 versus P = 0.032), particularly between October and April in women (P = 0.001) and October and January in men (P = 0.05). The ApoB/ApoA-I ratio in female CWS decreased over the season (P = 0.02), particularly between October and January (P = 0.05), and a trend toward the TG concentration to reduce over the swimming season was also observed in female CWS. No beneficial changes were noticed in the control group over the season. Our results suggest that the favorable effect of cold swimming on the cardiovascular risk factors may be gender-dependent; further studies are thus needed to draw a precise conclusion.
... It is difficult to distinguish whether adaptive effects arose from stimuli like cold, altitude, or high-intensity exercise. Winter swimmers (Vybíral et al., 2000) and female pearl divers from Korea (Tipton and Bradford, 2014), who are primarily exposed to cold water, may exhibit two or all three forms of cold adaptation (insulative, hypothermic, and metabolic) and, additionally, local cold adaptation. In winter swimmers shivering occurred considerably later during cooling when compared to not cold-adapted subjects, which was explained by reduced heat loss, more pronounced non-shivering thermogenesis, but less total heat production (Vybíral et al., 2000). ...
... Winter swimmers (Vybíral et al., 2000) and female pearl divers from Korea (Tipton and Bradford, 2014), who are primarily exposed to cold water, may exhibit two or all three forms of cold adaptation (insulative, hypothermic, and metabolic) and, additionally, local cold adaptation. In winter swimmers shivering occurred considerably later during cooling when compared to not cold-adapted subjects, which was explained by reduced heat loss, more pronounced non-shivering thermogenesis, but less total heat production (Vybíral et al., 2000). Insulative adaptation was demonstrated in the cold-adapted during swimming, and hypothermic adaptation occurred when only sitting in cold water (Tipton and Bradford, 2014). ...
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Living, working and exercising in extreme terrestrial environments are challenging tasks even for healthy humans of the modern new age. The issue is not just survival in remote environments but rather the achievement of optimal performance in everyday life, occupation, and sports. Various adaptive biological processes can take place to cope with the specific stressors of extreme terrestrial environments like cold, heat, and hypoxia (high altitude). This review provides an overview of the physiological and morphological aspects of adaptive responses in these environmental stressors at the level of organs, tissues, and cells. Furthermore, adjustments existing in native people living in such extreme conditions on the earth as well as acute adaptive responses in newcomers are discussed. These insights into general adaptability of humans are complemented by outcomes of specific acclimatization/acclimation studies adding important information how to cope appropriately with extreme environmental temperatures and hypoxia.
... They concluded that, through evidence of cold habituation occurring on both sides of the body, habituation is controlled more by central pathways as opposed to cutaneous receptors . Habituation has also been shown to attenuate responses to sudden cold water immersion, evidenced by reductions in sympathetic, tachycardia, and tachypnea responses (Kang et al., 1970;De Lorenzo et al., 1999;Vybiral et al., 2000;Huttunen et al., 2001;Westerlund et al., 2006;Barwood et al., 2007;Makinen et al., 2008;Li et al., 2009;Harper, 2012;Croft et al., 2013;Castellani and Young, 2016;Tipton, 2016). Habituation changes that lead to warmer skin, greater energy conservation, and improved comfort, with evidence suggesting that these originate more centrally than peripherally, may indeed have the ability to improve cognitive performance. ...
... However, trained and cold-acclimatized open water swimmers maintained thermal balance in 15°C water for upwards of 12 h (Pugh and Edholm, 2004). Lastly, insulative cold acclimation is characterized by a delayed onset of shivering (Hong, 1963;Hong et al., 1986;Park and Hong, 1991;Rintamaki et al., 1993;Livingstone et al., 1996;Vybiral et al., 2000;Kovtoun and Krivoschekov, 2001;Ferretti and Costa, 2003;Castellani and Young, 2016;Tipton, 2016), which conserves energy by reducing the amount of muscle activity required for heat generation. These changes, as they result in greater body heat retention, may improve cognitive activities that are more likely to be impacted by reductions in core temperature, such as memory and complex tasks. ...
Article
Athletes, occupational workers, and military personnel experience cold temperatures through cold air exposure or cold water immersion, both of which impair cognitive performance. Prior work has shown that neurophysiological pathways may be sensitive to the effects of temperature acclimation and, therefore, cold acclimation may be a potential strategy to attenuate cold-induced cognitive impairments for populations that are frequently exposed to cold environments. This review provides an overview of studies that examine repeated cold stress, cold acclimation, and measurements of cognitive performance to determine whether or not cold acclimation provides beneficial protection against cold-induced cognitive performance decrements. Studies included in this review assessed cognitive measures of reaction time, attention, logical reasoning, information processing, and memory. Repeated cold stress, with or without evidence of cold acclimation, appears to offer no added benefit of improving cognitive performance. However, research in this area is greatly lacking and, therefore, it is difficult to draw any definitive conclusions regarding the use of cold acclimation to improve cognitive performance during subsequent cold exposures. Given the current state of minimal knowledge on this topic, athletes, occupational workers, and military commands looking to specifically enhance cognitive performance in cold environments would likely not be advised to spend the time and effort required to become acclimated to cold. However, as more knowledge becomes available in this area, recommendations may change.
... Regular monitoring of SCH patients is necessary before the commencement of L-T4 replacement therapy as the condition can either progress to hypothyroidism or regress to normal thyroid function [37]. Thyroid hormone plays a major role in adaptive thermogenesis, an important target for T3 [38]. Mitochondrial uncoupling protein (UCP3) in skeletal muscle and the brown adipose tissue (BAT) is significantly related to cold-induced adaptive thermogenesis by the dissipation of heat due to uncoupling of the respiratory chain from oxidative phosphorylation [39]. ...
... The UCP3 is induced by T3 in addition to fatty acid [40]. The contribution of muscle is responsible on an average for 40% of thermogenesis in humans [38]. Most of the T3 in plasma comes from the conversion of T4 by extrathyroidal D2. ...
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Background: Various changes in thyroid hormones (TH) and thyroid-stimulating hormone (TSH) level were observed in different seasons among euthyroid and hypothyroid subjects living in areas with an extreme temperature difference between summer and winter. Objectives: This study aims at finding the effect of temperate climate on the seasonal variations of TSH and TH in euthyroid and subclinical hypothyroidism (SCH) subjects and at evaluating if the test season has an effect on the number of subjects diagnosed as SCH. It basically focuses on the relation of different components of climate with TH and TSH. Method: In a prospective study on 152 healthy (euthyroid) volunteers and 25 SCH subjects, the serum hormone levels (TSH, FT4, and FT3) were measured in both the summer and winter seasons and correlated with all the climate components using Pearson's correlation coefficient. The effect of duration of outdoor exposure on hormone levels was compared using a paired sample t-test (P < 0.05). Results: Small but statistically significant increased FT3 level and decreased FT4 level were observed during the winter season in euthyroid and SCH subjects, respectively. There was a significant negative correlation between FT3 and FT3/FT4 ratio with temperature and sunshine duration and a positive correlation with humidity and atmospheric pressure. A positive correlation was found between FT4 and sunshine duration. Conclusion: The climate components contributed to the slight variance in hormone levels in different seasons, and the effect was mostly on peripheral conversion of FT4 to FT3 rather than the pituitary-thyroid axis leading to slightly higher FT3 in winter. Seasonal variation does not affect the diagnosis of SCH cases.
... Adrenal medullary and thyroid hormones and sympathetic stimulation lead to increased activity of uncoupling proteins that reduce the oxidative phosphorylation, by this way increasing heat production (35). Studies have demonstrated the existence of adrenergic thermogenesis and the role of the sympathetic nervous system in controlling metabolic rate, heart rate, and vasomotion in humans exposed to cold (31,36,37). In addition to the increased metabolism, driven by thyroid and adrenal hormones, many changes in CV functions, such as vasoconstriction and raised BP, occur in response to cold. ...
... www.acsm-csmr.org Current Sports Medicine Reports 409 immersion (13°C) (36). The thermoregulatory functions of winter swimmers differed from those of non-cold-adapted subjects, wherein the magnitude of cold thermogenesis in winter swimmers was solely related to changes in rectal temperature, while in controls, a significant part of cold thermogenesis during the early phase of cooling was induced by changes in skin temperature input, and only in the late phase of cooling it was the central temperature input which was mainly involved in induction of cold thermogenesis. ...
Article
Winter swimming is a stressful condition of whole-body exposure to cold water; however, winter swimmers have achieved variable degrees of adaptation to cold. The question arises whether this extreme sport activity has any health benefits or whether it may confer potentially harmful effects. As a form of aerobic exercise, albeit more strenuous when performed in cold water, winter swimming may increase body tolerance to stressors and achieve body hardening. When practiced by individuals who are in good general health adopting a regular, graded and adaptive mode, winter swimming seems to confer cardiovascular (CV), and other health benefits. On the other hand, unaccustomed individuals are at risk of death either from the initial neurogenic cold-shock response, or from progressive decrease of swimming efficiency or from hypothermia. Furthermore, as it may occur with any intense exercise, individuals with evident or occult underlying CV conditions may be more susceptible to adverse effects with provocation of arrhythmias and CV events that may pose a significant health risk. Hence, a stepwise strategy to initiate and build up this recreational activity is recommended to enhance and sustain acclimation, achieve protection from potential risks of cold-water exposure and possibly avail from its promising health benefits. We need more data from prospective studies to better investigate the short- and long-term health consequences of this important recreational activity.
... It could be speculated that distinct and perhaps more efficient adaptive thermogenic mechanisms could develop in experienced (better acclimatized) ice-water swimmers. This notion is supported by the evidence of altered thermoregulatory responses present in ice-water swimmers during cold water immersion compared to controls (40). We observed that cold-induced thermogenesis seemed to be lower in cold-acclimatized individuals, which is in line with the previous reports (40), however BAT volume defined by the 18 FDG uptake seemed to be similar. ...
... The differential regulation of circulating PTH in cold-acclimatized individuals subjected to ice-water swimming and to non-shivering cold exposure could stem from the intensity of the cold stimulus, from the exercise component of ice-water swimming (47), from the postswimming shivering thermogenesis as well as from the difference in the body area exposed to cold (full-body cold water immersion vs. cooling pads). Meanwhile, the difference in coldinduced PTH regulation between cold acclimatized and non-acclimatized individuals could be related to the adaptive response to repeated cold water immersion, although we cannot rule out the effect of β3AR agonist and the fact that the shivering threshold in cold acclimatized individuals lies at much lower core body temperature (40). ...
Article
Cold-induced activation of thermogenesis modulates energy metabolism, but the role of humoral mediators is not completely understood. We aimed to investigate the role of parathyroid and thyroid hormones in acute and adaptive response to cold in humans. Examinations were performed before/after 15min ice-water swimming (IWS, n=15) or 120-150min of cold-induced non-shivering thermogenesis (NST) applied to cold-acclimatized (n=6) or non-acclimatized (n=11) individuals. Deep-neck brown adipose tissue (BAT) was collected from non-acclimatized patients undergoing elective neck surgery (n=36). Seasonal variations in metabolic/hormonal parameters of ice-water swimmers were evaluated. We found that in ice-water swimmers, PTH and TSH increased and free T3, T4 decreased after 15min winter swim while NST inducing cold exposure failed to regulate PTH and free T4 and lowered TSH and free T3. Ice-water swimming-induced increase in PTH correlated negatively with systemic calcium and positively with phosphorus. In non-acclimatized men, NST-inducing cold decreased PTH and TSH. Positive correlation between systemic levels of PTH and whole-body metabolic preference for lipids as well as BAT volume was found across the two populations. Moreover, NST-cooling protocol-induced changes in metabolic preference for lipids correlated positively with changes in PTH. Finally, variability in circulating PTH correlated positively with UCP1/UCP1, PPARGC1A and DIO2 in BAT from neck surgery patients. Our data suggest that regulation of PTH and thyroid hormones during cold exposure in humans varies by cold acclimatization level and/or cold stimulus intensity. Possible role of PTH in NST is indicated by its positive relationships with whole-body metabolic preference for lipids, BAT volume and UCP1 content.
... In Eastern Europe and Russia, winter swimming is part of the celebration of Epiphany [21]. Naturally, many field studies investigating the influence of cold water swimming on the body come from these northern countries on various topics such as adaptation to the cold [22], changes in lipid metabolism [23,24], adjustments to hematological values [25,26], effects on the immune system [27][28][29][30] and the hormones [5,31] or aspects of thermoregulation [32][33][34][35]. Events in which large numbers of people swim over a relatively short distance in cold water in winter can also be called classic winter swimming. ...
... Acclimatization to cold develops over the course of about 10 days, and the primary change is a hypothermic type of response [98]. In winter swimmers, shivering was induced later during cooling (after 40 min) than in controls suggesting an important participation of non-shivering thermogenesis in the early thermogenic response [34]. It has been shown during cold water immersion that dynamic core temperature significantly contributed to the magnitude of metabolic heat production and that individual differences existed in central thermosensitivity [99]. ...
Article
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Cold water swimming (winter or ice swimming) has a long tradition in northern countries. Until a few years ago, ice swimming was practiced by very few extreme athletes. For some years now, ice swimming has been held as competitions in ice-cold water (colder than 5 °C). The aim of this overview is to present the current status of benefits and risks for swimming in cold water. When cold water swimming is practiced by experienced people with good health in a regular, graded and adjusted mode, it appears to bring health benefits. However, there is a risk of death in unfamiliar people, either due to the initial neurogenic cold shock response or due to a progressive decrease in swimming efficiency or hypothermia.
... 50% af kroppen ligger mindre end 2,5 cm fra hudoverfladen, og det giver mening, at den samlede naturlige isolering er kombinationen af fedt og muskler [34]. Samtidig er en veltraenet og en kuldeadapteret person i stand til at holde legemstemperaturen ved øgning af metabolismen i laengere tid, før kulderystelse saetter ind [34,35]. Dette sker hos den kuldeadapterede vintersvømmer ved katekolamininduceret termogenese, formentlig ved en receptorsensitivitetsøgning [35]. ...
... Samtidig er en veltraenet og en kuldeadapteret person i stand til at holde legemstemperaturen ved øgning af metabolismen i laengere tid, før kulderystelse saetter ind [34,35]. Dette sker hos den kuldeadapterede vintersvømmer ved katekolamininduceret termogenese, formentlig ved en receptorsensitivitetsøgning [35]. Således er langdistancesvømmere, der krydser Den Engelske Kanal, i stand til at holde en konstant legemstemperatur på den minimum 32 km lange svømmetur uden brug af isolerende våddragt (vandtemperatur 15-18°C) [36]. ...
... Por otra parte podemos encontrar pocas referencias respecto a la forma física y termorregulación en ambientes fríos. Pero en nadadores de invierno, se ha observado una reducción del umbral termoregulatorio para la inducción de la termogénesis y un retraso en la respuesta del temblor (Vybiral, Lesna, Jansky, Zeman, 2000). ...
... Mäkinen et al. [4] reported that some individuals exhibited increased VO 2 without shivering during a 24-h period of cold exposure (10°C) in winter. In addition, Vybúral [5] reported the importance of hormonal effects on NST in winter swimmers. These results suggested that seasonal acclimatization of thermogenesis occurred by including NST. ...
Article
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The physiological function of non-shivering thermogenesis (NST) has been investigated in recent years, and some studies have discussed the importance of NST with respect to human cold adaptation. The present study aimed to clarify individual and seasonal variations in NST that occurred as a result of mild cold exposure. Seventeen male university students participated in the present study during summer and winter. The climate chamber used was programmed so that ambient temperature dropped from 28°C to 16°C over an 80-min period. Physiological parameters of test subjects were recorded during the experiments. Increases in oxygen intake (VO2) during cold exposure were significantly greater without shivering in winter than they were in summer. Respiratory exchange ratio (RER) was significantly lower during thermoneutral baseline and cold exposure in winter than it was during the same periods in summer. In addition, there was a significant negative correlation between ΔVO2 and ΔRER. Increase of VO2 without shivering indicated increase of NST, and decrease of RER depends on the metabolization of fat in winter. These results suggested that NST activity was activated by seasonal acclimatization, and individual variation of NST depends on individual variation of fat metabolism.
... A key phenomenon responsible for adaptation of winter swimmers to cold water immersion is the decreased dermal perfusion leading to improved thermo-isolating function of the skin [7,8]. The lower perfusion, in turn, results from a decreased cardiac output and cardiac rate, as well as the constriction of dermal blood vessels [9,10]. ...
Article
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Introduction: Exposure to cold is one of the strongest physiological and psychological environmental stressors and induces an array of significant functional responses. Objective: To analyze the changes in morphological and rheological parameters of blood in regular winter swimmers and individuals exposed to whole-body cryotherapy. Methods: The study covered a period of two months (February and March) and included two groups of healthy males: 1) 10 winter swimmers who immersed in cold waters (3 min at 2°C to 7.2°C) once a week, and 2) 10 healthy volunteers who were exposed to cryotherapy (3 min at -110°C) on a weekly basis. Venous blood for morphological, biochemical (glu¬cose, fibrinogen) and rheological analysis (aggregation index, the amplitude and total extent of aggregation, the half time of the aggregation) was sampled prior to the experiment, as well as after one and two months of regular exposure to cold. Results: After two months of winter swimming, significant reduction of plasma fibrinogen was documented as compared to the baseline level. In contrast to winter swimmers, after two months of cryotherapy plasma concentration of fibrinogen was significantly higher than prior to the experiment. Moreover, significant increase in platelet count and the reduction in glucose concentration were documented after two months as compared the first month of cryotherapy.Conclusions: This study confirmed that exposure to cold can modulate morphological and biochemical parameters of blood. Despite the lack of unfavorable changes in hemorheological indices of both studied groups, an increase in fibrinogen concentration documented in cryotherapy group points to potential risk associated with this form of cold exposure.
... Interestingly, cold acclimation did cause significantly lower adrenalin levels during thermoneutral condition and higher levels during mild cold stimulation. This is in line with the trend found by Vyb ıral et al. (Vybiral et al. 2000), who found that winter swimmers have nonsignificant (trend) lower adrenalin levels during cold exposure when compared with control subjects. A possible explanation might be an increased sensibility of the adrenergic receptor. ...
Article
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Low environmental temperatures have a profound effect on biological processes in the body, including the immune system. Cold exposure coincides with hormonal changes, which may directly or indirectly alter the immune system, even in the skeletal muscle. The aim of the present study was to investigate the effect of cold acclimation on immune composition in skeletal muscle. Skeletal muscle biopsies were obtained from 17 healthy lean subjects before and after 10 days of mild cold exposure (15 °: C, 6 h/day). Nonshivering thermogenesis was calculated by indirect calorimetry. We found that cold acclimation increased nonshivering thermogenesis from 10.8 ± 7.5 before to 17.8 ± 11.1% after cold acclimation (P < 0.01), but did not affect plasma catecholamine nor cytokine levels. In contrast, cold acclimation affected mRNA expression of several immune cell markers in skeletal muscle. It downregulated expression of the Th17 markers RORC (-28%, P < 0.01) and NEDD4L (-15%, P < 0.05), as well as the regulatory T-cell marker FOXP3 (-13%, P < 0.05). Furthermore, cold acclimation downregulated expression of the M2 macrophage markers CCL22 (-50%, P < 0.05), CXCL13 (-17%, P < 0.05) and CD209 (-15%, P < 0.05), while the M1 macrophage marker IL12B was upregulated (+141%, P < 0.05). Cold acclimation also enhanced several markers related to interferon (IFN) signaling, including TAP1 (+12%, P < 0.01), IFITM1/3 (+11%, P < 0.05), CD274 (+36%, P < 0.05) and STAT 2 (+10%, P < 0.05). In conclusion, 10 days of intermittent cold exposure induces marked changes in the expression of immune cell markers in skeletal muscle of healthy lean subjects. The physiological consequences and therapeutic relevance of these changes remain to be determined. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.
... By catalyzing cytoplasm ATP into cAMP, Fat kinase was activated to strengthen lipolysis. More free fatty acids were produced to supply abundant substrates for oxidative phosphorylation of tissues, leading to the enhancement of tissue heat production [20]. ...
Article
Exercise in cold environments can cause significant metabolic regulation and antioxidant behavior. For discussing enzymatic responses towards cold adaptation, we investigated enzyme activities of adenylate cyclase (AC) and phosphodiesterase (PDE) in liver, skeletal muscle, and brown adipose tissue (BAT), as well as Na(+)·K(+) ATPase and Na(+)/K(+) ratio in blood. Malondialdehyde (MDA) and superoxide dismutase (SOD) activity in blood were also studied to address the effect of cold adaptation on oxidative damage and antioxidant system. Experimental results indicated that enzyme activities in liver, skeletal muscle and BAT maintained relatively constant for the control group. For the cold adaptation group, enzyme activities in liver and skeletal muscle were in high levels at the beginning, and then gradually decreased to similar values with the control group. However, enzyme activities in BAT performed an increasing trend and significantly higher than the control at the end. In addition, decreased oxidative damage and activated antioxidant system was observed along with the cold adaptation process.
... • Prior acclimatization to cold (for a period of 10 days) may increase the BAT activity and non-shivering thermogenesis (64). Indeed winter swimmers show bradycardia and lower plasma volume that suggests a lower degree of heat loss when exposed to cold (66). • Large inter-individual variations exist in response to cold. ...
Article
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Objective: Brown adipose tissue (BAT) is involved in energy dissipation and cytokine production and is potentially beneficial for the human body. The aim of the paper is to review the literature on adiposity-related cancer and functional imaging of BAT. Methods: We performed a review on adiposity-related cancer and functional imaging of BAT. We extensively researched papers for information on BAT molecular biology, as well as functional imaging modalities. Results: Adipose tissue is linked to the development of many cancers. Multiple drugs including fenofibrate, spironolactone, and other substances, as well as experimental agents like β-3 receptor agonists, caffeine, green tea extract, medium chain triglycerides (MCTs), and adenosine are known to stimulate and activate BAT. However, cold and nonshivering thermogenesis are the main activators of BAT. BAT has been detected on both magnetic resonance imaging (MRI) and 18F-fluorodexoxyglucose positron emission tomography (18F-FDG-PET)-based imaging in multiple studies. Different methods of cold stimulation and static and dynamic protocols have been used to detect and image BAT. Factors like sex, fasting or fed state, surface skin temperature, and/or body mass index (BMI) may influence PET-based BAT detection. BAT has also been detected using MRI, (99m)Technetium (Tc)-sestamibi, and 123I-metaiodobenzylguanidine single-photon emission computed tomography/computed tomography (MIBG SPECT/CT). Conclusions: Stimulation of BAT offers promise in the management of obesity-related conditions. Tracers like [(15)O]-H2O, [(11)C] acetate, and 18F-fluoro-6-thia-heptadecanoic acid (18F-FTHA) that measure BAT blood flow, oxygen utilization, and nonessential fatty acid (NEFA) uptake, respectively, have been studied in humans. Future studies should focus on BAT tissue generation by altering the genetic pathways of adiposity-linked genes.
... There is some evidence to suggest that an individual athlete can partially physiologically adapt to cold-water (Vybiral et al., 2000). Conversely, heat acclimation adaptations do not seem to occur as readily in swimmers as upright land-based athletes (D.F. ...
Article
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Elite athletes who compete in aquatic sports face the constant challenge of arduous training and competition schedules in difficult and changing environmental conditions. The huge range of water temperatures to which swimmers and other aquatic athletes are often exposed (16-31°C for open water swimming), coupled with altered aquatic thermoregulatory responses as compared to terrestrial athletes, can challenge the health, safety and performance of these athletes. Other environmental concerns include air and water pollution, altitude and jetlag/travel fatigue. However, these challenging environments provide the potential for several nutritional interventions that can mitigate the negative effects and enhance adaptation and performance. These interventions include providing adequate hydration, carbohydrate (CHO) and iron intake while at altitude; optimizing body composition and fluid and CHO intake when training or competing in varying water temperatures; and maximizing fluid and food hygiene when travelling. There is also emerging information on nutritional interventions to manage jetlag and travel fatigue, such as the timing of food intake and the strategic use of caffeine or melatonin. Aquatic athletes often undertake their major global competitions where accommodations feature cafeteria-style buffet eating. These environments can often lead to inappropriate choices in the type and quantity of food intake, which is of particular concern to divers and synchronized swimmers who compete in physique-specific sports, as well as swimmers who have a vastly reduced energy expenditure during their taper. Taken together, planned nutrition and hydration interventions can favorably impact upon aquatic athletes facing varying environmental challenges.
... Cryotherapy as an emerging physiotherapy gradually accepted and used by more athletes and coaches, cryotherapy originate from Japan, the main application is to treat rheumatism clinical diseases (Westerlund 2009), and in the following nearly 30 years, especially in Europe and the United States and other countries began to develop rapidly (Westerlund et al. 2006;Cholewka et al. 2006;Vybiral et al. 2000;Lu et al. 2021). Application field also gradually extended from clinical medicine to sports medicine, and further application in the practice of sports training, it can be a good pain relief, speed recovery and reduce the inflammatory response after injury, so for athletes can be a good means of recovery. ...
Article
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The purpose of this study was to investigate the influence of cryotherapy on the balance ability after lower extremity muscle fatigue. Twelve table tennis players were selected in this research. The static and dynamic balance abilities of the participants at six different moments were collected by a 1000 HZ Kistler force platform and Y balance test system. SPSS19.0 software was used to analyze the results of experimental indicators by selecting two-factor repeated measurement ANOVA. 1) From the moment of 24 h post intervention, the effect of cryotherapy on dynamic balance recovery was significantly better than no cryotherapy. 2) Except for the COP (Center of Pressure) maximum displacement on ML (Medium-Lateral axis) at the moment of 72 h post intervention, the cryotherapy had no positive effect on the recovery of static balance ability. 3) Cryotherapy has a significant negative impact on the COP maximum displacement in ML and AP (Antero-Posterior axis) at the moment of post cryotherapy, which may lead to the decline of static balance ability. It was not recommended to use cryotherapy for balance recovery if the competition was on the same day or within 24 h. However, the cryotherapy was recommended to use if the competition was in the next day or after the next day.
... Pyrexia is common clinical feature of malaria which may result in hyperthermia leading to dehydration. The hypothalamic control of temperature involves water loss as a compensatory mechanism to lower the raised body temperature (Vybiral et al., 2000). This may explain the reduction in salivary flow rate of malaria positive individuals because dehydration has been associated with reduced salivary flow rate (Falcao et al., 2013). ...
Article
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No previous studies have documented changes in salivary secretion in patients with malaria. This study aimed to compare salivary secretion and composition in malaria positive and malaria negative individuals. Ninety participants composed of 40 malaria parasite positive and 50 malaria parasite negative individuals (age and gender matched) were included. Malaria diagnosis was achieved by microscopic examination of Giemsa stained thick and thin film of blood smears. A self-administered questionnaire was used to assess presence or absence of oral symptoms in the malaria parasite positive individuals. Whole saliva samples were collected and analyzed for flow rate, pH, total protein and concentrations of electrolytes (K+, Na+, Ca2+, Cl-, PO42-and HCO32-). Data were analysed using Independent-Samples t-test and Spearman's correlation test. The salivary flow rate was significantly reduced in malaria parasite positive individuals (P = 0.001). Oral symptoms were present in 82.5% of the malaria parasite positive individuals. There was no significant difference in the salivary pH, total protein and electrolyte ion concentrations between the two groups. Also, Spearman's correlation test showed no significant relationship between the presence of oral symptom and the salivary parameters. Salivary flow rates are reduced in the individuals with malaria. However, presence of oral symptoms in these individuals may not be attributed to the reduced salivary flow rate. Further studies are needed to validate our findings and elucidate mechanisms involved.
... Pod wpływem zanurzenia się w zim- nej wodzie pojawiają się istotne zmia- ny w składzie krwi. Zaliczamy do nich między innymi zwiększenie zawarto- ści hemoglobiny o 10-20%, wzrost hematokrytu, zmniejszenie liczby bia- łych krwinek, zwiększenie liczby pły- tek krwi, zwiększenie lepkości krwi, zwiększenie stężenia glukozy 1,2 . ...
Article
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Objective: The aim of this study was to determine the effect of regular winter swimming on the morphological parameters of blood and the distribution of body surface temperature among winter swimmers. Methods: The study involved 10 winter swimmers from the "Kaloryfer" Krakow Club of Winter Swimmers. During winter, from November through April, they regularly (once per week) immerse themselves in cold water. Venous blood samples were collected twice: at the beginning of the season and after the season. Thermal images were taken three minutes before immersion in cold water and immediately after it. Results: Swimming in cold water induced a significant increase in red blood cells and haematocrit and a significant decrease in mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. No changes were found in white blood cells, platelets, haemoglobin or mean corpuscular volume. Body surface temperature decreased due to immersion in cold water. Conclusions: Regular winter swimming results in considerable, non-pathological changes in haematological parameters and body surface temperature among winter swimmers.
... A number of researchers have studied the adaptation of nonshivering thermogenesis (NST) after repeated cold exposures in humans (Vybiral et al. 2000;van Marken Lichtenbelt and Daanen 2003;van Marken Lichtenbelt and Schrauwen 2011;van der Lans et al. 2013;Yoneshiro et al. 2013;Nishimura et al. 2015). Recently, brown adipose tissue (BAT) have been focused on as one of the major components of energy expenditure, since cold-induced activity of BAT in adult humans had been identified in studies using PET/CT scanning (Saito et al. 2009;van Marken Lichtenbelt et al. 2009). ...
Article
This study aimed to investigate the effect of repeated cooling of forearm muscle on adaptation in skeletal muscle metabolism. It is hypothesized that repeated decreases of muscle temperature would increase the oxygen consumption in hypothermic skeletal muscle. Sixteen healthy males participated in this study. Their right forearm muscles were locally cooled to 25 °C by cooling pads attached to the skin. This local cooling was repeated eight times on separate days for eight participants (experimental group), whereas eight controls received no cold exposure. To evaluate adaptation in skeletal muscle metabolism, a local cooling test was conducted before and after the repeated cooling period. Change in oxy-hemoglobin content in the flexor digitorum at rest and during a 25-s isometric handgrip (10% maximal voluntary construction) was measured using near-infrared spectroscopy at every 2 °C reduction in forearm muscle temperature. The arterial blood flow was occluded for 15 s by upper arm cuff inflation at rest and during the isometric handgrip. The oxygen consumption in the flexor digitorum muscle was evaluated by a slope of the oxy-hemoglobin change during the arterial occlusion. In the experimental group, resting oxygen consumption in skeletal muscle did not show any difference between pre- and post-intervention, whereas muscle oxygen consumption during the isometric handgrip was significantly higher in post-intervention than in pre-test from thermoneutral baseline to 31 °C muscle temperature (P < 0.05). This result indicated that repeated local muscle cooling might facilitate oxidative metabolism in the skeletal muscle. In summary, skeletal muscle metabolism during submaximal isometric handgrip was facilitated after repeated local muscle cooling.
... A key phenomenon responsible for adaptation of winter swimmers to cold water immersion is the decreased dermal perfusion leading to improved thermo-isolating function of their skin [32]. The lower perfusion, in turn, results from a decreased cardiac output and cardiac rate, as well as the constriction of dermal blood vessels [37,44]. Consequently, adaptation of the circulatory system to winter swimming is of vital importance and could include changes in the rheological properties of erythrocytes, particularly their deformability under shear force. ...
Article
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The aim of this study was to analyze the changes in blood rheology resulting from regular winter swimming. The study was carried out on 12 male winter swimmers. Venous blood for morphological, biochemical and rheological analysis was sampled twice from each winter swimmer - at the beginning of the season and after its completion. There were no significant changes detected in the median values of most blood morphological parameters. The only exception pertained to MCHC which was significantly lower after the season. Winter swimming entailed significant decrease in median elongation index values at shear stress levels of 0.30 Pa and 0.58 Pa, and significant increase in median values of this parameter at shear stress levels ≥1.13 Pa. No significant changes were observed in winter swimmers' median values of aggregation indices and plasma viscosity. The median level of glucose was lower post winter swimming in comparison to the pre-seasonal values. In contrast, one season of winter swimming did not influence swimmers' median value of fibrinogen concentration. In summary, this study revealed positive effects of winter swimming on the rheological properties of blood, manifested by an increase in erythrocyte deformability without accompanying changes in erythrocyte aggregation.
... 19,20 Subjects did not perceive less shivering during the seventh immersion, even though our EMG data showed reduced shivering. This study observed no change in T core , a decrease in skin temperature, and attenuated shivering and lactate responses in cold-acclimated humans, which are in agreement with other authors, [17][18][19]23 and supports successful CA. Findings from the pre-and post-CA heat stress trials revealed that all physiological and perceptual measurements increased during exercise in the heat. ...
Article
Introduction: Warfighters often train and conduct operations in cold environments. Specifically, military trainees and divers that are repeatedly exposed to cold water may experience inadvertent cold acclimatization, which results in body heat retention. These same warfighters can quickly switch between environments (cold to hot or hot to cold) given the nature of their work. This may present a risk of early onset of hyperthermia when cold-acclimatized warfighters are subsequently exposed to physiological insults that increase body temperature, such as exercise and heat stress. However, there is currently no evidence that suggests this is the case. The purpose of this work, therefore, is to determine what impact, if any, repeated immersion in cold water has on subsequent exercise in the heat. Materials and methods: Twelve healthy subjects (values in mean ± SD: age, 25.6 ± 5.2 years; height, 174.0 ± 8.9 cm; weight, 75.6 ± 13.1 kg) voluntarily provided written informed consent in accordance with the San Diego State University Institutional Review Board. They first completed 120 minutes of moderate treadmill walking in 40°C and 40% relative humidity. During this trial, subjects' physiological and perceptual responses were recorded. Twenty-four hours later, subjects began a cold acclimation protocol, which consisted of seven, 90-minute immersions in cold water (10°C, water level to chest). Each immersion was also separated by 24 hours. Subjects then repeated a subsequent trial of exercise in the heat 24 hours after the final immersion of the cold acclimation protocol. Results: Results from cold acclimation revealed no change in core temperature, a decrease in skin temperature, and attenuated shivering and lactate responses, which supports a successful insulative-hypothermic cold acclimation response. This type of cold acclimation response primarily results in heat retention with associated energy conservation. Findings for heat trials (pre-cold acclimation and post-cold acclimation) revealed no differences between trials for all measurements, suggesting that cold acclimation did not influence physiological or perceptual responses during exercise in the heat. Conclusion: Our findings indicate that military divers or trainees that are frequently exposed to cold water, and hence have the ability to experience cold acclimatization, will likely not be at greater risk of increased thermal strain when subsequently exposed to physical activity in hot environments. In this study, no physiological or perceptual differences were observed between trials before and after cold acclimation, suggesting that cold acclimation does not present a greater hyperthermia risk during subsequent exercise in the heat.
... The accuracy of blood samples from an ear immediately after swimming in cold water might be limited. On the other hand, strength of this study was its novelty as previous studies on swimming in cold used shorter exercise distances such as 150 m (22) or warmer water temperatures (40). Further studies should consider the circadian rhythm of cortisol excretion as this hormone undergoes a circadian rhythm, which could have influenced the preswim values. ...
Article
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‘Ice Mile’ swimming (i.e. 1,608m in water of below 5°C) is becoming increasingly popular. Since the foundation of the International Ice Swimming Association (IISA) in 2009, official races are held as World Cup Races and World Championships. Ice swimming was a demonstration sport at the 2014 Winter Olympics in Sochi, Russia. This case study aimed to identify body core temperature and selected haematological and biochemical parameters before and after repeated ‘Ice Miles’. An experienced ice swimmer completed six consecutive ‘Ice Miles’ within two days. Swim times, and changes in body core temperatures, and selected urinary and haematological parameters were recorded. The athlete showed after each ‘Ice Mile’ a metabolic acidosis (i.e. increase in lactate and TCO2; decrease in base excess and HCO3−) and an increase in blood glucose, cortisol and creatine kinase concentration. The decrease in pH correlated significantly and negatively with the increase in cortisol level, indicating that this intense exercise causes a metabolic stress. The change in body core temperature between start and finish was negatively associated with metabolic acidosis. The increase in creatine kinase suggests a skeletal muscle damages due to shivering after an ‘Ice Mile’. For athletes and coaches, swimming in cold water during ‘Ice Miles’ leads to a metabolic acidosis which the swimmer tried to compensate with a respiratory response. Considering the increasing popularity of ice swimming, the findings have practical value for swimmers and practitioners (e.g. coaches, exercise physiologists, and physicians) working with them as our results provide a detailed description of acute physiological responses to repeated swimming in cold conditions. These findings are of importance for athletes and coaches for National Championships and World Championships in Ice Swimming following the IISA rules. Key words: cold water; aquatic sports; hypothermia; thermal stress
... Various forms of thermal stimulation with the use of a cold temperature are differentiated in the academic literature. that most often applied and described is cryostimulation -local or general (cryochamber) with the use of nitrogen vapour or carbon dioxide at temperatures of from -60°c to -160°c at up to three minutes in length (2,4,8,9,12,(22)(23)(24)(25)28). In the stimulation defined as cold water immersion (cwM) water at a temperature of from 8°c to 15°c is used. ...
... In this study no changes in thyroid hormones (TSH, FT4) were found, probably due to the intermittent cold exposure and the short duration of the intervention. No changes in noradrenaline levels were found upon cold acclimation, and adrenaline levels were significantly lower in thermoneutral condition, which is in line with the trend found by Vybíral et al. (34), with winter swimmers having a nonsignificant (trend) lower adrenalin level during cold exposure when compared with control subjects. A possible explanation might be an increased sensibility of the receptor. ...
Article
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In recent years, it has been shown that humans have active brown adipose tissue (BAT) depots, raising the question of whether activation and recruitment of BAT can be a target to counterbalance the current obesity pandemic. Here, we show that a 10-day cold acclimation protocol in humans increases BAT activity in parallel with an increase in nonshivering thermogenesis (NST). No sex differences in BAT presence and activity were found either before or after cold acclimation. Respiration measurements in permeabilized fibers and isolated mitochondria revealed no significant contribution of skeletal muscle mitochondrial uncoupling to the increased NST. Based on cell-specific markers and on uncoupling protein-1 (characteristic of both BAT and beige/brite cells), this study did not show "browning" of abdominal subcutaneous white adipose tissue upon cold acclimation. The observed physiological acclimation is in line with the subjective changes in temperature sensation; upon cold acclimation, the subjects judged the environment warmer, felt more comfortable in the cold, and reported less shivering. The combined results suggest that a variable indoor environment with frequent cold exposures might be an acceptable and economic manner to increase energy expenditure and may contribute to counteracting the current obesity epidemic.
... Blagojević i wsp. [29]. Janský i wsp. ...
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... Adrenergic stimulation has been shown to be important for the CA-elicited shift from shivering to nonshivering thermogenesis (53). Importantly, we previously documented a desensitization of adrenergic responsiveness of the cardiovascular system in winter swimmers (27,55). It is known that heart function is predominantly under the control of ␤-adrenergic signaling. ...
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... W czasie nagłego ochłodzenia dochodzi do wzrostu stężenia we krwi hormonów stresu. W celu pobudzenia produkcji ciepła dochodzi do pojawienia się dreszczy i nasilenia termogenezy drżeniowej [17,18]. Drżenie mięśniowe obniża z kolei zdolność do podejmowania wysiłku poprzez zmniejszenie koordynacji mięśniowej oraz związane z pracą mięśni zmęczenie. ...
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Korzystne działanie zimna na organizm człowieka znane jest już od czasów starożytnych. Obecnie chętnie wykorzystywane jest w fizjoterapii oraz odnowie biologicznej. Zalety działania zimna na organizm znane są też morsom – entuzjastom kąpieli w zimnych akwenach wodnych w okresie zimowym. Celem niniejszej pracy jest przedstawienie korzyści oraz zagrożeń wynikających z uprawiania tej formy rekreacji. Zimno stanowi silny środek przeciwbólowy oraz pobudza wiele procesów fizjologicznych, przyczyniając się w ten sposób do szybszego odzyskiwania sprawności. W Polsce i na świecie, co roku wzrasta liczba zwolenników lodowatych kąpieli. Morsowanie stało również się przedmiotem interesujących badań dla naukowców. Zauważono, że regularna ekspozycja na niską temperaturę przyczynia się do poprawy samopoczucia, przyspiesza regenerację po wysiłku oraz chroni przed szkodliwym działaniem wolnych rodników. Morsowanie zwiększa ponadto tolerancję na zimno i przyczynia się do hartowania ciała. Należy jednak pamiętać, że gwałtowne ochłodzenie organizmu wiąże się z pewnym ryzykiem. Wyniki dotychczasowych badań potwierdzają korzystny wpływ uprawiania tej formy rekreacji na zdrowie człowieka. Przy zachowaniu odpowiednich środków ostrożności morsowanie może być wyjątkowym sposobem spędzania wolnego czasu i sposobnością poznania interesujących osób.
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Reviews on whole body human cold adaptation generally do not distinguish between population studies and dedicated acclimation studies, leading to confusing results. Population studies show that indigenous black Africans have reduced shivering thermogenesis in the cold and poor cold induced vasodilation in fingers and toes compared to Caucasians and Inuit. About 40,000 y after humans left Africa, natives in cold terrestrial areas seems to have developed not only behavioral adaptations, but also physiological adaptations to cold. Dedicated studies show that repeated whole body exposure of individual volunteers, mainly Caucasians, to severe cold results in reduced cold sensation but no major physiological changes. Repeated cold water immersion seems to slightly reduce metabolic heat production, while repeated exposure to milder cold conditions shows some increase in metabolic heat production, in particular non-shivering thermogenesis. In conclusion, human cold adaptation in the form of increased metabolism and insulation seems to have occurred during recent evolution in populations, but cannot be developed during a lifetime in cold conditions as encountered in temperate and arctic regions. Therefore, we mainly depend on our behavioral skills to live in and survive the cold.
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Mammals have evolved complex mechanisms to obtain energy from food; store excess energy in the forms of glycogen, fat, and protein; and utilize energy efficiently for vital functions. Obesity develops when energy intake exceeds energy expenditure. While obesity treatment is mostly focused on reducing food intake, studies suggest that increasing energy expenditure through physical activity and adaptive thermogenesis is an important strategy for weight loss and maintenance of health. This chapter will describe fundamental concepts of bioenergetics and provide a framework for understanding the pathogenesis and treatment of metabolic syndrome.
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Mammals have evolved complex mechanisms to obtain energy from food; store excess energy in the forms of glycogen, fat, and protein; and utilize energy efficiently for vital functions. Obesity develops when energy intake exceeds energy expenditure. While obesity treatment is mostly focused on reducing food intake, studies suggest that increasing energy expenditure through physical activity and adaptive thermogenesis is an important strategy for weight loss and maintenance of health. This chapter will describe fundamental concepts of bioenergetics and provide a framework for understanding the pathogenesis and treatment of metabolic syndrome.
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This article reviews published data on the main types of adaptation of humans to cold and the mechanisms increasing heat production. Studies in recent years addressing the molecular mechanisms of adaptation to cold are shown to confirm results from earlier physiological investigations demonstrating that the main contribution to adaptive thermogenesis on cooling is provided by oxidative fibers in skeletal muscle (birds, marsupials, large placental mammals, and humans) and brown fat (small placental mammals, particularly rodents). The main increase in heat production occurs as a result of contractile activity (shivering and thermoregulatory muscle tone), uncoupling of oxidative phosphorylation, and decreases in the efficiency (energy conversion efficiency, ECE) of cellular pumps (ATPases), which is induced by noradrenaline and thyroid hormones and is accompanied by increases in the consumption of oxygen and energy substrates. Prolonged cold adaptation leads to increases in the number and activity of mitochondria to provide for increasing levels of ATP consumption.
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The aim is to reveal the features of microcirculation of athletes with various sport qualifications practicing cyclic endurance sports, as well as its dependence on the VEGF (vascular endothelial growth factor) level and hematological parameters. Research materials and methods. The study involved athletes aged 18-22 practicing track-and-field (middle and long distances, from 1st rank to Master of Sports of the Russian Federation), swimming (middle distances, from 1st rank to Master of Sports of the Russian Federation), skiing (from 1st rank to Master of Sports of the Russian Federation), and non-athletes. We utilized a laser detection to record parameters of peripheral blood flow and tissue fluorescence amplitudes. Research results and discussion. We recorded significant difference in microcirculation parameters for skiers and field athletes. Skiers demonstrated a lower value of average perfusion, while field athletes showed its double predominance in contrast with skiers. At the same time, cooling of the studied area caused no difference between the studied groups. Heating of the studied area resulted in the statistically significant changes in microcirculation between groups of skiers in contrast with field athletes and swimmers, as well as swimmers, in contrast with field athletes and non-athletes. At the same time, the VEGF level had correlations with the microcirculation of field athletes, and it was recorded with the NADN parameter under the cooling (r = 0.89; p = 0.019) and heating (r = 0, 94; p = 0.005) conditions. Conclusion. We revealed the signs of long-term adaptation of peripheral blood flow of athletes conditioned by the type and conditions of sport activities. It results in difference in perfusion of the studied skin area.
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The effects of repeated cold water immersion on thermoregulatory responses to cold air were studied in seven males. A cold air stress test (CAST) was performed before and after completion of an acclimation program consisting of daily 90-min cold (18 degrees C) water immersion, repeated 5 times/wk for 5 consecutive wk. The CAST consisted of resting 30 min in a comfortable [24 degrees C, 30% relative humidity (rh)] environment followed by 90 min in cold (5 degrees C, 30% rh) air. Pre- and postacclimation, metabolism (M) increased (P less than 0.01) by 85% during the first 10 min of CAST and thereafter rose slowly. After acclimation, M was lower (P less than 0.02) at 10 min of CAST compared with before, but by 30 min M was the same. Therefore, shivering onset may have been delayed following acclimation. After acclimation, rectal temperature (Tre) was lower (P less than 0.01) before and during CAST, and the drop in Tre during CAST was greater (P less than 0.01) than before. Mean weighted skin temperature (Tsk) was lower (P less than 0.01) following acclimation than before, and acclimation resulted in a larger (P less than 0.02) Tre-to-Tsk gradient. Plasma norepinephrine increased during both CAST (P less than 0.002), but the increase was larger (P less than 0.004) following acclimation. These findings suggest that repeated cold water immersion stimulates development of true cold acclimation in humans as opposed to habituation. The cold acclimation produced appears to be of the insulative type.
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The purpose of this study was to monitor changes in body and skin temperatures, heat production, subjective shivering, cold sensation and body fat content in humans after intermittent cold water immersion. Repeated exposures of young sportsmen to cold water (head out, 14 degrees C, 1 h, 3 times per week for 4-6 weeks) induced changes in regulation of thermal homeostasis. "Cold acclimated" subjects exhibited an hypothermic type of adaptation. Central and peripheral body temperatures at rest and during cold immersion were lowered. The metabolic response to cold was delayed and subjective shivering was attenuated. The observed hypothermia was due to the shift of the threshold for induction of cold thermogenesis to lower body temperatures. "Cold acclimated" subjects also showed a lowered cold sensation. Because of the observed physiological changes, about 20% of the total heat production was saved during one cold water immersion of "cold acclimated" subjects. Maximal aerobic and anaerobic performances were not altered. No change in the thermosensitivity of the body temperature controller, as assessed from the unchanged slope of the relation between the deep body temperature and total heat production, was observed. Changes in cold sensation and regulation of cold thermogenesis were noticed first after four cold water immersions and persisted for at least 2 weeks after termination of the adaptation procedure. A trend towards a small increase in the body fat content was also observed. This finding, as well as the increased vasoconstriction, evidenced by the lowered skin temperature, indicate that slight changes in body insulation may also occur after "cold acclimation" in humans.
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Metabolic responses, skin temperatures and changes in heart rate and blood pressure were measured in a control group and in “polar swimmers” after infusion of different doses of epinephrine, norepinephrine and isoprenaline. In controls the highest infusion dose of isoprenaline (0.1 μg min−1 kg−1) increased metabolic rate in normal humans by 36%, while the highest infusion doses of epinephrine and norepinephrine (0.45 μg min−1 kg−1) increased metabolic rate by 24%, only. In “polar swimmers” the epinephrine thermogenesis was potentiated significantly, reaching about 45% of the basal metabolic rate. The norepinephrine and isoprenaline thermogenesis were not different from that of the control group. It is concluded that in humans the epinephrine thermogenesis is probably located in muscles and in the white fat (Simonsen et al., 1992), and may be the principal mechanism of metabolic adaptation to cold. It was calculated that the increased capacity of epinephrine thermogenesis in cold exposed “polar swimmers” could theoretically shift the survival limit downwards to lower environmental temperatures by about 5°C.
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Two types of cold exposures were carried out in humans. A. Fourteen subjects were exposed 4–7 times within 2 weeks to the following conditions: ambient temperature was decreased from 28° C to between plus and minus 5°C; the subjects wore a bathing suit and remained in a resting position during the exposure which lasted for 1 h. B. Nine conscripts were studied before and after a 10-day exercise, during which they were exposed to moderately cold conditions during day and night. The exercise did not require increased physical activity. In two thirds of the subjects A, metabolic reactions and shivering threshold were shifted to a lower weighted mean body temperature as well as a lower esophageal temperature (“hypothermic” type of adaptation). This modification in the thermoregulatory system was linked with a reduction in thermal discomfort and cold sensation. No change was found in the resting metabolic rate nor was there any indication of the development of non-shivering thermogenesis. Similar modifications were found in 4 of the 9, soldiers (study B). These 4, however, had particularly high shivering thresholds before the 10-day exercise and the values found thereafter were no lower than those found in the remaining five and in the subjects of group A before the cold-exposure regimen.
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Different types of general cold adaptation have been described over the last 50 years. Metabolic adaptation (Alacaluf Indians, Arctic Indians Eskimos), insulative adaptation (coastal Aborigines of tropical northern Australia), hypothermic adaptation (bushmen of the Kalahari desert, Peruvian Indians) and insulative hypothermic adaptation (Central Australian Aborigines, nomadic Lapps, Korean and Japanese diving women). These different types of cold adaptation are related to the intensity of the cold stress and to individual factors such as diet, the level of physical fitness and body fat content. Thus, in natural environments, man develops a strategy of adaptation to cold, which takes into account environmental and individual factors. This strategy is susceptible to be modified when these conditions change. Caloric intake deficit could have been responsible for the hypothermic adaptation observed after J.-L. Etienne's journey to the North Pole. Physiological responses were adapted to maintain an acceptable level of energetic reserves with a moderate hypothermia, which was not life threatening for the climatic conditions encountered by the polar explorer.
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In cutaneous veins of the dog, cooling augments the response to sympathetic nerve stimulation and exogenous norepinephrine (NE). The postjunctional alpha adrenoceptors in this blood vessel belong to both the alpha 1 and alpha 2 subtypes. Cooling augments alpha 2-adrenergic responses (presumably because of an increased receptor affinity), but depresses alpha 1-adrenergic responses (presumably because of a direct inhibitory effect on the contractile process). When agonists of high efficacy such as NE or phenylephrine are used, an alpha 1-adrenoceptor reserve is present that buffers the response from the inhibitory effect of cooling. This allows the potentiating effect of cold on the alpha 2-adrenergic component of the response to catecholamines to predominate, and the contractile response to exogenous NE and sympathetic nerve stimulation is augmented. By contrast, in deep veins of the limb, cold reduces the contractions evoked by alpha 1- and alpha 2-adrenergic activation. This can be explained best by the absence of a receptor reserve for alpha 1-adrenergic agonists of high efficacy, combined with a reduced density of postjunctional alpha 2 adrenoceptors.
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1. The present investigation was designed to examine human adaptation to intermittent severe cold exposure and to assess the effect of exercise on any adaptation obtained. 2. Sixteen subjects were divided into two equal groups. Each subject performed ten head-out immersions; two into thermoneutral water which was then cooled until they shivered vigorously, and eight into water at 15 degrees C for 40 min. During the majority of the 15 degrees C immersions, one group (dynamic group) exercised whilst the other (static group) rested. 3. Results showed that both groups responded to repeated cold immersions with a reduction in their initial responses to cold. The time course of these reductions varied, however, between responses. 4. Only the static group developed a reduced metabolic response to prolonged resting immersion. 5. It is concluded that repeated resting exposure to cold was the more effective way of producing an adaptation. The performance of exercise during repeated exposure to cold prevented the development of an adaptive reduction in the metabolic response to cold during a subsequent resting immersion. In addition, many of the adaptations obtained during repeated resting exposure were overridden or masked during a subsequent exercising immersion.
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Several types of cold adaptation in men have been described in the literature (metabolic, insulative, hypothermic). The aim of this study is to show that the decrease of heat debt can be considered as a new index for cold adaptation. Ten male subjects were acclimated by water immersions (temperature 10-15 degrees C, 4 immersions/wk over 2 mo). Thermoregulatory responses before and after acclimation were tested by a standard cold test in a climatic chamber for 2 h at rest [dry bulb temperature (Tdb): 10 degrees C; relative humidity (rh): 25%]. After adaptation, four thermoregulatory modifications were observed: an increase in the delay for the onset of shivering (32.7 +/- 7.99 instead of 14.1 +/- 5.25 min); a decrease of body temperature levels for the onset of shivering [rectal temperature (Tre): 37.06 +/- 0.08 instead of 37.31 +/- 0.06 degrees C; mean skin temperature (Tsk): 24.83 +/- 0.56 instead of 26.86 +/- 0.46 degrees C; mean body temperature (Tb): 33.03 +/- 0.20 instead of 34.16 +/- 0.37 degrees C); a lower level of body temperatures in thermoneutrality (Tre = 37.16 +/- 0.08 instead of 37.39 +/- 0.06 degrees C; Tsk = 31.29 +/- 0.21 instead of 32.01 +/- 0.22 degrees C; Tb = 35.92 +/- 0.08 instead of 36.22 +/- 0.05 degrees C); a decrease of heat debt calculated from the difference between heat gains and heat losses (5.66 +/- 0.08 instead of 8.33 +/- 0.38 kJ/kg). The different types of cold adaptation observed are related to the physical characteristics of the subjects (percent body fat content) and the level of physical fitness (VO2max).(ABSTRACT TRUNCATED AT 250 WORDS)
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Observations on hematocrit (Hct) and hemoglobin (Hb) were made in 6 men before and after running long enough to cause a 4% decrease in body weight. Subscripts B and A were used to denote before dehydration and after dehydration, respectively. Relations were derived between BV(b), BV(a), HB(b), Hb(a), Hct(b), and Hct(a) with which the percentage decreases in BV, CV, and PV can be calculated, as well as the concentration of hemoglobin in red cells, g/100 ml-1 (MCHC). When subjects reach the same level of dehydration the water loss from the various body compartments may vary reflecting the difference in salt losses in sweat. Changes in PV calculated from the increase in plasma protein concentration averaged -7.5% compared with -12.2% calculated from changes in Hb and Hct. The difference could be accounted for by a loss of 6% plasma protein from the circulation.
Article
Thermoregulatory responses were studied in 10 men and 8 women at rest in air and during 1-h immersion in water at 20, 24, and 28 degrees C. For men of high body fat (27.6%), rectal temperature (Tre) and oxygen consumption (VO2) were maintained at air values at all water temperatures (Tw). For men of average (16.8%) and low (9.2%) fat the change in Tre (delta Tre) was inversely related to body fat at all Tw with VO2 increasing to 1.07 l X min-1 for a -1.6 degrees C delta Tre for lean men. For women of average (25.2%) and low (18.5%) fat Tre decreased steadily during immersion at all Tw. The greatest changes occurred at 20 degrees C with little differences in delta Tre and VO2 noted between these groups of women. In comparison with males of similar percent fat, Tre dropped to a greater extent (P less than 0.05) in females at 20 and 24 degrees C. Stated somewhat differently, lean women with twice the percentage of fat have similar delta Tre as lean men at all Tw. For delta Tre greater than -1.0 degree C men showed significantly greater (P less than 0.05) thermogenesis compared with women. The differences in thermoregulation between men and women during cold stress at rest may be due partly to the sensitivity of the thermogenic response as well as the significant differences in lean body weight and surface area-to-mass ratio between the sexes.
Article
Elevated plasma adrenaline is known to increase whole body energy expenditure. We studied the thermogenic effect and the effects on substrate utilization in man during infusion of adrenaline. Two series were performed: in one series skeletal muscle metabolism was investigated and in another series subcutaneous adipose tissue metabolism was investigated. In both series Fick's principle was applied. Intravenous infusion increased blood flow, glucose uptake and oxygen uptake in both skeletal muscle and adipose tissue. It is concluded that skeletal muscle contributes about 40% and adipose tissue about 5% of the whole body adrenaline-induced thermogenesis.
Human adaptability to cold
  • L Jansk Y
Jansk y, L. (1998). Human adaptability to cold. In Problems with Cold Work, ed. Holm er, I. & Kuklane, K., Proceedings of the Symposium, Stockholm, Arbete och Halsa, Vetenskaplig
Cold-adaptive modifications in man induced by repeated short-term cold-exposures during a 10-day and -night cold-exposure
  • K Bruck
  • E Baum
  • H P Schvennicke
Bruck, K., Baum, E. & Schvennicke, H. P. (1976). Cold-adaptive modifications in man induced by repeated short-term cold-exposures during a 10-day and -night cold-exposure. Pfl ugers Archiv 363, 125-133.