Physiological responses and thermal sensation in the recovery period after extremely cold exposure

Two osmoprotectants (proline – Pro; trehalose – Tre) were exogenously supplied to seedlings of rice cvs. Pokkali (PK – salt-tolerant) and Khao Dawk Mali 105 (KDML105 – salt-sensitive) to investigate their effects on plants exposed to 200 mmol/L NaCl for 6 days and 5 days after recovery from stress. The reduction of growth, increase in Na+ to K+ ratio, high level of hydrogen peroxide (H2O2) content, enhanced activity of antioxidant enzymes (superoxide dismutase – SOD, peroxidase – POX, catalase – CAT and ascorbate peroxidase – APX) were observed in both rice cultivars under NaCl treatments. Exogenous Pro and Tre supplement to NaCl-stressed plants did not mitigate the reduction of growth during salt-stress. Nevertheless, during recovery plants previously supplied with Tre showed markedly higher percentage of growth recovery than those treated with NaCl alone or supplied with Pro. The beneficial effect of Tre on growth recovery was clearly demonstrated in KDML105 in which growth enhancement was related to reduction in Na+ to K+ ratio. Exogenous Pro was able to reduce H2O2 in both cultivars during salt stress whereas Tre could reduce it only in KDML105. Exogenous Tre did not enhance any antioxidant enzymes during stress but enhanced APX activity in KDML105 during recovery. Exogenous Pro enhanced the activity of APX in PK, and POX, CAT and APX in KDML105 during both stress and recovery period.

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Infrared thermal imaging as a method to study thermogenesis in the neonatal lamb

Animal Production Science ◽

10.1071/an14301 ◽

2014 ◽

Vol 54 (9) ◽

pp. 1497 ◽

Cited By ~ 5

Author(s):

S. A. McCoard ◽

H. V. Henderson ◽

F. W. Knol ◽

S. K. Dowling ◽

J. R. Webster

Keyword(s):

Body Temperature ◽

Heat Loss ◽

Cold Exposure ◽

Thermal Imaging ◽

Core Body Temperature ◽

Recovery Period ◽

Exposure Period ◽

Skin Surface ◽

Infrared Thermal Imaging ◽

Core Body

The combination of heat generation and reducing heat loss from the skin surface is important for maintaining core body temperature in a neonate. Thermogenesis studies traditionally focus on measurement of core body temperature but not the contribution of radiated heat loss at the skin surface. This study aimed to evaluate the utility of using thermal imaging to measure radiated heat loss in newborn lambs. Continuous thermal images of newborn lambs were captured for 30 min each during the baseline (11−18°C), cold-exposure (0°C) and recovery (11−18°C) periods by using an infrared camera. Core body temperature measured by rectal thermometer was also recorded at the end of each period. In all, 7 of the 10 lambs evaluated had reduced rectal temperatures (0.4−1°C) between the baseline and recovery periods, while three maintained body temperature despite cold exposure. During the baseline period, infrared heat loss was relatively stable, followed by a rapid decrease of 5°C within 5 min of cold exposure. Heat loss continued to decrease linearly in the cold-exposure period by a further 10°C, but increased rapidly to baseline levels during the recovery period. A temperature change of between 20°C and 35°C was observed during the study, which was likely to be due to changes in vasoconstriction in the skin to conserve heat. The present study has highlighted the sensitivity of infrared thermal imaging to estimate heat loss from the skin in the newborn lamb and shown that rapid changes in heat loss occur in response to cold exposure.

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Acclimatization of Scottish Blackface sheep to cold. 2. Skin temperature, heart rate, respiration rate, shivering intensity and skinfold thickness

Animal Production ◽

10.1017/s0003356100025903 ◽

1968 ◽

Vol 10 (1) ◽

pp. 17-35 ◽

Cited By ~ 20

Author(s):

A. R. Sykes ◽

J. Slee

Keyword(s):

Heart Rate ◽

Skin Temperature ◽

Cold Exposure ◽

Chronic Exposure ◽

Physiological Responses ◽

Skinfold Thickness ◽

Acute Exposure ◽

Heart Rates ◽

Ambient Temperatures ◽

Acute Cold Exposure

Closely shorn Scottish Blackface female sheep aged 9–14 months, half on high plane and half on low plane nutrition, were subjected, in climate chambers, to two short acute cold exposures down to −20°C. The acute exposures were separated by two weeks chronic exposure to a moderately subcriticai temperature (+8°C) or to a thermoneutral temperature (+30°C). Most of the sheep showed a greater resistance to body cooling at the second acute exposure (Slee and Sykes, 1967). This increased resistance to hypothermia, defined as acclimatization, was apparently influenced more by acute than by chronic cold exposure. The present paper deals with changes in skin temperature, heart rate, shivering intensity and skinfold thickness which also resulted from cold exposure, and accompanied acclimatization.After acute cold exposure followed by chronic exposure to +8°C the following changes in these parameters were observed:1. Extremity skin temperatures and heart rates were consistently increased at thermoneutral ambient temperatures.2. Vasoconstriction of the extremities and increased heart rate, both of which normally occur during the early stages of cold exposure, were delayed.3. Heart rates at sub-zero ambient temperatures were increased.4. Cold-induced vasodilatation at sub-zero ambient temperatures was increased.After acute cold treatment alone the intensity of shivering during the second acute exposure was reduced. Also the onset of foot vasoconstriction was slightly delayed.A highly significant relationship was observed between shivering intensity and heart rate during cold exposure.Plane of nutrition had less effect on the physiological responses to cooling than did previous cold experience.It was suggested in discussion that the physiological responses associated with acclimatization were: elevated basal metabolic rate, delayed onset of vasoconstriction and delayed metabolic response to cold, and consequent lowering of the critical temperature. Summit metabolism was also increased and shivering intensity reduced during acute cold exposure. Some of these responses could have resulted from either acute or chronic moderate cold exposure. However their persistence, once induced, appeared to depend upon continued exposure to moderate cold.

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Correction: Physiological responses to acute cold exposure in young lean men

PLoS ONE ◽

10.1371/journal.pone.0200865 ◽

2018 ◽

Vol 13 (7) ◽

pp. e0200865 ◽

Cited By ~ 3

Author(s):

Francisco M. Acosta ◽

Borja Martinez-Tellez ◽

Guillermo Sanchez-Delgado ◽

Juan M. A. Alcantara ◽

Pedro Acosta-Manzano ◽

...

Keyword(s):

Cold Exposure ◽

Physiological Responses ◽

Acute Cold Exposure

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Exertional fatigue and cold exposure: mechanisms of hiker's hypothermia

Applied Physiology Nutrition and Metabolism ◽

10.1139/h07-041 ◽

2007 ◽

Vol 32 (4) ◽

pp. 793-798 ◽

Cited By ~ 7

Author(s):

Andrew J. Young ◽

John W. Castellani

Keyword(s):

Heat Loss ◽

Cold Exposure ◽

Physiological Responses ◽

Physical Exertion ◽

The Body ◽

Cold Weather ◽

Behavioral Strategies ◽

Peripheral Vasoconstriction ◽

Vasoconstrictor Response ◽

Body Heat

Participants in prolonged, physically demanding activities in cold weather are at risk of a condition known as “hiker's hypothermia”. During exposure to cold weather, the increased gradient favoring body heat loss to the environment must be balanced by physiological responses, clothing, and behavioral strategies that conserve body heat stores, or else body temperature will decline. The primary human physiological responses elicited by cold exposure are shivering and peripheral vasoconstriction. Shivering increases thermogenesis and replaces body heat losses, while peripheral vasoconstriction improves thermal insulation of the body and retards the rate of heat loss. A body of scientific literature supports the concept that prolonged and (or) repeated cold exposure, fatigue induced by sustained physical exertion, or both together can impair shivering and vasoconstrictor response to cold. The mechanisms accounting for this thermoregulatory impairment are not clear, but the possibility that changes in blood glucose availability or sympathetic responsiveness to cold due to exertion and fatigue merit further research.

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Influences of age and gender on human thermoregulatory responses to cold exposures

Journal of Applied Physiology ◽

10.1152/jappl.1985.58.1.180 ◽

1985 ◽

Vol 58 (1) ◽

pp. 180-186 ◽

Cited By ~ 63

Author(s):

J. A. Wagner ◽

S. M. Horvath

Keyword(s):

Older Women ◽

Body Fat ◽

Young Women ◽

Cold Exposure ◽

Physiological Responses ◽

Metabolic Cost ◽

Older Men ◽

Age And Gender ◽

Younger Women ◽

And Gender

To delineate age- and gender-related differences in physiological responses to cold exposure, men and women between the ages of 20 and 29 yr and 51 and 72 yr, wearing minimal clothing, were exposed at rest for 2 h to 28, 20, 15, and 10 degrees C room temperatures with 40% relative humidity. During the coldest exposure, the rates of increase in metabolic rate (W X m-2 or ml X kg lean body mass-1 X min-1 were similar for all groups. However, older women (n = 7) may have benefited from a larger (P less than 0.05) early metabolic (M) increase (40% within 15 min) than young men (18%) (n = 10), young women (5%) (n = 10), or older men (5%) (n = 10). A similar rapid M response in older women occurred during the 15 degrees C exposure. During all cold exposures, older women maintained constant rectal temperature (Tre) and young women maintained Tre only during the 20 degrees C exposures, whereas Tre of the men declined during all cold exposures (P less than 0.01). Changes in Tre and mean skin temperature (Ts) during cold exposure were largely related to body fat, although age and surface area/mass modified the changes in men. The data suggest that older men are more susceptible to cold ambients than younger people, since they did not prevent a further decline in their initially relatively low Tre. Despite greater insulation from body fat, the older women maintained a constant Tre at greater metabolic cost than men or younger women.

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Cooling During Exercise May Induce Benefits Linked to Improved Brain Perfusion

International Journal of Sports Medicine ◽

10.1055/a-1213-5960 ◽

2020 ◽

Author(s):

Wafa Douzi ◽

Benoit Dugué ◽

Dimitri Theurot ◽

Ludwig Vinches ◽

Stéphane Hallé ◽

...

Keyword(s):

Heart Rate ◽

Skin Temperature ◽

Cooling System ◽

Heart Rate Recovery ◽

Physiological Responses ◽

Recovery Period ◽

Subjective Rating ◽

Brain Level ◽

The Impact ◽

The Brain

AbstractThe aim of this study was to evaluate the impact of using a cooling vest during physical exercise (per-cooling) in humid and temperate conditions (≈22°C, ≈80% relative humidity) on perceptual and physiological responses (tissue oxygenation and heart rate). 20 physically active men performed twice a 30-min cycling exercise at 70% of their theoretical maximum heart rate while using an activated (experimental condition) and a deactivated (control condition) cooling system in a randomized crossover study. Heart rate and tissue (cerebral and muscular) oxygenation were continuously measured during exercise and recovery, and skin temperature was measured every 10 min. Perception of temperature, humidity and comfort were assessed at the end of the recovery period. Results showed a decrease in trunk skin temperature (p<0.05), a faster heart rate recovery and an increase in the concentration of total hemoglobin at the brain level (p<0.05) compared with control condition. Moreover, an improved subjective rating of thermal sensations, wetness and comfort compared to control values (p<0.05) was noted. In conclusion, wearing a cooling vest during submaximal exercise improves perceptual and physiological responses in humid temperate conditions, which may be due to a better blood perfusion at the brain level and a better parasympathetic reactivation.

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Effects of different cooling principles on thermal sensation and physiological responses

Energy and Buildings ◽

10.1016/j.enbuild.2013.01.007 ◽

2013 ◽

Vol 62 ◽

pp. 116-125 ◽

Cited By ~ 23

Author(s):

Lisje Schellen ◽

Marcel G.L.C. Loomans ◽

Martin H. de Wit ◽

Bjarne W. Olesen ◽

Wouter D. van Marken Lichtenbelt

Keyword(s):

Thermal Sensation ◽

Physiological Responses

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Drinking Behavior and Exercise-Thermal Stress: Role of Drink Carbonation

International Journal of Sport Nutrition ◽

10.1123/ijsn.4.1.8 ◽

1994 ◽

Vol 4 (1) ◽

pp. 8-21 ◽

Cited By ~ 4

Author(s):

Matthew S. Hickey ◽

David L. Costill ◽

Scott W. Trappe

Keyword(s):

Thermal Stress ◽

Body Fluid ◽

Prolonged Exercise ◽

Physiological Responses ◽

Drinking Behavior ◽

Recovery Period ◽

Fluid Consumption ◽

Blood Samples ◽

Ad Libitum

This study investigated the influence of drink carbonation and carbohydrate content on ad libitum drinking behavior and body fluid and electrolyte responses during prolonged exercise in the heat. Eight competitive male runners completed three 2-hr treadmill runs at 60%in an environmental chamber maintained atand 40% RH. Three test drinks were used: 8% carbohydrate, low carbonation (8%-C); 8% carbohydrate, noncarbonated (8%-NC), and water (0%-NC). Blood samples were taken preexercise (0), at 60 and 120 min of exercise, and at 60 min of recovery (+60 min). The data suggest that while reports of heartburn tend to be higher on 8% carbohydrate drinks than on 0%-NC, this does not appear to be a function of drink carbonation. Similarly, the increased frequency of heartbum did not significantly reduce fluid consumption either during exercise or during a 60-min recovery period. Importantly, no differences were observed between fluid and electrolyte, or thermoregulatory responses to the three sport drinks. Thus, consumption of low-carbonation beverages does not appear to significantly influence drinking behavior or the related physiological responses during prolonged exercise in the heat.

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