Computer Simulation of Thermoregulatory Responses to Heat Stress: A Future Work Design and Training Tool

1977 ◽  
Vol 21 (2) ◽  
pp. 142-146
Author(s):  
Jerry R. Duncan
Keyword(s):  
Heat Stress ◽  
Skin Temperature ◽  
Absolute Difference ◽  
Mean Skin Temperature ◽  
Body Segment ◽  
Minute Exposure ◽  
Blood Flows ◽  
Thermoregulatory Responses ◽  
Stress Environments ◽  
And Task

A mathematical model of human thermoregulation was developed to simulate thermoregulatory responses of man exposed to heat stress environments. The model was validated with experimental results of a man pedalling in environments of 35 and 45°C dry-bulb and 33 mm Hg water vapor pressure. The model inputs of body segment temperatures, thermal characteristics, basal blood flows, basal heat production, and of environmental and task characteristics permitted the model to be “individualized” for a specific subject, environment, and task. The model outputs of body segment temperatures, blood flows, and sweat loss at designated intervals permitted observation of the dynamic thermoregulatory responses over a 60 minute exposure period. The model was successful in predicting the change in thermal responses of a clothed man working in heat stress environments. Over the 60 minute exposure at 45°C the mean absolute difference between experimental and simulated values of head skin temperature was 0.28°C. The difference for trunk mean skin temperature was 0.12°C; for body mean skin temperature, 0.29°C; and for internal body temperature, 0.53°C.

Thermoregulatory responses during competitive marathon running

1977 ◽  
Vol 42 (6) ◽  
pp. 909-914 ◽  
Author(s):  
M. B. Maron ◽  
J. A. Wagner ◽  
S. M. Horvath
Keyword(s):  
Skin Temperature ◽  
Marathon Running ◽  
Heat Illness ◽  
Mean Skin Temperature ◽  
Total Water ◽  
Water Losses ◽  
Thermoregulatory Responses ◽  
Marked Disparity ◽  
Skin Temperatures ◽  
Cool Conditions

To assess thermoregulatory responses occuring under actual marathon racing conditions, rectal (Tre) and five skin temperatures were measured in two runners approximately every 9 min of a competitive marathon run under cool conditions. Race times and total water losses were: runner 1 = 162.7 min, 3.02 kg; runner 2 = 164.6 min, 2.43 kg. Mean skin temperature was similar throughout the race in the two runners, although they exhibited a marked disparity in temperature at individual skin sites. Tre plateaued after 35--45 min (runner 1 = 40.0--40.1, runner 2 = 38.9--39.2 degrees C). While runner 2 maintained a relatively constant level for the remainder of the race, runner 1 exhibited a secondary increase in Tre. Between 113 and 119 min there was a precipitous rise in Tre from 40.9 to 41.9 degrees C. Partitional calorimetric calculations suggested that a decrease in sweating was responsible for this increment. However, runner 1's ability to maintain his high Tre and running pace for the remaining 44 min of the race and exhibit no signs of heat illness indicated thermoregulation was intact.

Active cutaneous vasodilation in resting humans during mild heat stress

2005 ◽  
Vol 98 (3) ◽  
pp. 829-837 ◽  
Author(s):  
Yoshi-Ichiro Kamijo ◽  
Kichang Lee ◽  
Gary W. Mack
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Skin Temperature ◽  
Skin Blood Flow ◽  
Sweat Rate ◽  
Mean Skin Temperature ◽  
Local Skin ◽  
Mild Heat ◽  
Normal Core ◽  
Local Sweat Rate

The role of skin temperature in reflex control of the active cutaneous vasodilator system was examined in six subjects during mild graded heat stress imposed by perfusing water at 34, 36, 38, and 40°C through a tube-lined garment. Skin sympathetic nerve activity (SSNA) was recorded from the peroneal nerve with microneurography. While monitoring esophageal, mean skin, and local skin temperatures, we recorded skin blood flow at bretylium-treated and untreated skin sites by using laser-Doppler velocimetry and local sweat rate by using capacitance hygrometry on the dorsal foot. Cutaneous vascular conductance (CVC) was calculated by dividing skin blood flow by mean arterial pressure. Mild heat stress increased mean skin temperature by 0.2 or 0.3°C every stage, but esophageal and local skin temperature did not change during the first three stages. CVC at the bretylium tosylate-treated site (CVCBT) and sweat expulsion number increased at 38 and 40°C compared with 34°C ( P < 0.05); however, CVC at the untreated site did not change. SSNA increased at 40°C ( P < 0.05, different from 34°C). However, SSNA burst amplitude increased ( P < 0.05), whereas SSNA burst duration decreased ( P < 0.05), at the same time as we observed the increase in CVCBT and sweat expulsion number. These data support the hypothesis that the active vasodilator system is activated by changes in mean skin temperature, even at normal core temperature, and illustrate the intricate competition between active vasodilator and the vasoconstrictor system for control of skin blood flow during mild heat stress.

Human thermoregulatory responses during cold water immersion after artificially induced sunburn

1992 ◽  
Vol 262 (4) ◽  
pp. R617-R623 ◽  
Author(s):  
K. B. Pandolf ◽  
R. W. Gange ◽  
W. A. Latzka ◽  
I. H. Blank ◽  
A. J. Young ◽  
...  
Keyword(s):  
Skin Temperature ◽  
Rectal Temperature ◽  
Cold Water ◽  
Water Immersion ◽  
Cold Water Immersion ◽  
The Body ◽  
Esophageal Temperature ◽  
Mean Skin Temperature ◽  
Thermoregulatory Responses ◽  
The Mean

Thermoregulatory responses during cold-water immersion (water temperature 22 degrees C) were compared in 10 young men before as well as 24 h and 1 wk after twice the minimal erythemal dose of ultraviolet-B radiation that covered approximately 85% of the body surface area. After 10 min of seated rest in cold water, the mean exercised for 50 min on a cycle ergometer (approximately 51% of maximal aerobic power). Rectal temperature, regional and mean heat flow (hc), mean skin temperature from five sites, and hearrt rate were measured continuously for all volunteers while esophageal temperature was measured for six subjects. Venous blood samples were collected before and after cold water immersion. The mean skin temperature was higher (P less than 0.05) throughout the 60-min cold water exposure both 24 h and 1 wk after sunburn compared with before sunburn. Mean hc was higher (P less than 0.05) after 10 min resting immersion and during the first 10 min of exercise when 24 h postsunburn was compared with presunburn, with the difference attributed primarily to higher hc from the back and chest. While rectal temperature and heart rate did not differ between conditions, esophageal temperature before immersion and throughout the 60 min of cold water immersion was higher (P less than 0.05) when 24 h postsunburn was compared with presunburn. Plasma volume increased (P less than 0.05) after 1 wk postsunburn compared with presunburn, whereas plasma protein concentration was reduced (P less than 0.05). After exercise cortisol was greater (P less than 0.05) 24 h postsunburn compared with either presunburn or 1 wk postsunburn.(ABSTRACT TRUNCATED AT 250 WORDS)

INCREASING MEAN SKIN TEMPERATURE LINEARLY REDUCES THE VASOCONSTRICTION AND SHIVERING THRESHOLDS IN HUMANS

1994 ◽  
Vol 81 (SUPPLEMENT) ◽  
pp. A252
Author(s):  
C. Cheng ◽  
T. Matsukawa ◽  
A. Kurz ◽  
D. I. Sessler ◽  
B. Merrifield
Keyword(s):  
Skin Temperature ◽  
Mean Skin Temperature

Comparative Efficacy of Physiological Responses and Skin Temperatures in Indigenous and Crossbred Cattle Supplemented with Chlorophytum borivilianum in Summer Season

2021 ◽  
Author(s):  
Pooja Devi ◽  
Mahendra Singh ◽  
Yallappa M. Somagond ◽  
A.K. Roy
Keyword(s):  
Heat Stress ◽  
Skin Temperature ◽  
Physiological Responses ◽  
High Dose ◽  
Crossbred Cattle ◽  
Comparative Efficacy ◽  
Production Potential ◽  
Chlorophytum Borivilianum ◽  
Humidity Index ◽  
Skin Temperatures

Background: Heat stress causes oxidative stress and declines milk production potential of cows. The physiological responses and skin temperature of heat stressed animals are good indices for deterring the heat stress. The efficacy of medicinal herb Chlorophytum borivilianum (CB) was tested in lowering the rise in values of physiological responses and skin temperature in crossbred vis a vis Indigenous cows. Methods: Eighteen Tharparkar (TP) and Crossbred KF cows in mid-lactation were given; No supplement (control), a low (T1, n=6) and a high dose (T2, n=6) of CB @ 40 and 80 mg/kg BW/day, respectively for 90 days during hot-humid season. Respiration rate (RR), pulse rate (PR), rectal temperature (RT) and skin temperature (ST) was recorded at the site of forehead, neck, rear body, and udder surface in the morning and afternoon at weekly intervals. Temperature-humidity index (THI) was calculated to assess the degree of thermal stress in animals. Result: Physiological responses and skin temperatures were higher (p less than 0.01) in the afternoon than morning intervals in TP and KF cows. CB feeding significantly lowered physiological responses and ST (p less than 0.01) in high dose as compared to low dose. It was concluded that CB feeding @ 80 mg/kg BW/day effectively alleviates the heat stress. Indigenous cows were found more heat tolerant in comparison to crossbred cows.

The effect of hand immersion on body temperature when wearing impermeable clothing

1991 ◽  
Vol 77 (1) ◽  
pp. 41-47
Author(s):  
A. J. Allsopp ◽  
Kerry A. Poole
Keyword(s):  
Body Temperature ◽  
Skin Temperature ◽  
Environmental Temperature ◽  
List Type ◽  
Physiological Measures ◽  
Total Work ◽  
Mean Skin Temperature ◽  
Work Time ◽  
Experimental Conditions ◽  
Rest Periods

AbstractThe effects of hand immersion on body temperature have been investigated in men wearing impermeable NBC clothing. Six men worked continuously at a rate of approximately 490 J.sec−1 in an environmental temperature of 30°C. Each subject was permitted to rest for a period of 20 minutes when their aural temperature reached 37.5°C, and again on reaching 38°C, and for a third time on reaching 38.5°C (three rest periods in total). Each subject completed three experimental conditions whereby, during the rest periods they either: a.Did not immerse their hands (control).b.Immersed both hands in a water bath set at 25°c.c.Immersed both hands in water at 10°C.Physiological measures of core temperature, skin temperature and heart rate were recorded at intervals throughout the experiment.Measures of mean aural temperature and mean skin temperature were significantly (P<0.05) reduced if hands were immersed during these rest periods, compared to non immersion. As a result, the total work time of subjects was extended when in the immersed conditions by some 10–20 minutes within the confines of the protocol.It is concluded that this technique of simple hand immersion may be effective in reducing heat stress where normal routes to heat loss are compromised.

Thermoregulatory responses of dogs after alteration of peripheral sensitivity

1962 ◽  
Vol 202 (6) ◽  
pp. 1237-1240 ◽  
Author(s):  
R. H. Helmendach ◽  
J. P. Meehan
Keyword(s):  
Skin Temperature ◽  
Thermal State ◽  
Skin Sensitivity ◽  
Thermoregulatory Responses ◽  
Rapid Changes ◽  
It Application ◽  
Pharmacologic Agents

Topically applied pharmacologic agents were used to alter skin sensitivity of unanesthetized dogs subjected to rapid changes in thermal state. The anesthetic pramoxine hydrochloride was utilized to depress peripheral sensitivity; menthol was used to enhance it. Application of these agents produced shifts in specific skin temperature at which activation and suppression of both panting and shivering occur. These changes were interpreted as indicating peripheral mediation in control of thermoregulatory end mechanisms. Both substances exhibited a greater effect on thermoregulatory responses to cooling than to heating. Consequently, one may infer that the peripheral cold-fiber effect exerts a greater influence on thermoregulatory end mechanisms than does the warm-fiber effect.

scholarly journals Blood Flow Distribution during Heat Stress: Cerebral and Systemic Blood Flow

2013 ◽  
Vol 33 (12) ◽  
pp. 1915-1920 ◽  
Author(s):  
Shigehiko Ogoh ◽  
Kohei Sato ◽  
Kazunobu Okazaki ◽  
Tadayoshi Miyamoto ◽  
Ai Hirasawa ◽  
...  
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Carotid Artery ◽  
Flow Distribution ◽  
Systemic Circulation ◽  
External Carotid Artery ◽  
Whole Body ◽  
External Carotid ◽  
Blood Flows ◽  
Induced Changes

The purpose of the present study was to assess the effect of heat stress-induced changes in systemic circulation on intra- and extracranial blood flows and its distribution. Twelve healthy subjects with a mean age of 22±2 (s.d.) years dressed in a tube-lined suit and rested in a supine position. Cardiac output (Q), internal carotid artery (ICA), external carotid artery (ECA), and vertebral artery (VA) blood flows were measured by ultrasonography before and during whole body heating. Esophageal temperature increased from 37.0±0.2°C to 38.4±0.2°C during whole body heating. Despite an increase in Q (59±31%, P<0.001), ICA and VA decreased to 83±15% ( P=0.001) and 87±8% ( P=0.002), respectively, whereas ECA blood flow gradually increased from 188±72 to 422±189 mL/minute (+135%, P<0.001). These findings indicate that heat stress modified the effect of Q on blood flows at each artery; the increased Q due to heat stress was redistributed to extracranial vascular beds.

scholarly journals Effect of food intake on the ventilatory response to increasing core temperature during exercise

2019 ◽  
Vol 44 (1) ◽  
pp. 22-30 ◽  
Author(s):  
Keiji Hayashi ◽  
Nozomi Ito ◽  
Yoko Ichikawa ◽  
Yuichi Suzuki
Keyword(s):  
Food Intake ◽  
Body Temperature ◽  
Skin Temperature ◽  
Core Temperature ◽  
Mean Skin Temperature ◽  
Carbon Dioxide Elimination ◽  
Transient Effect ◽  
Mean Body Temperature ◽  
Ventilatory Parameters ◽  
Effect Of Food

Food intake increases metabolism and body temperature, which may in turn influence ventilatory responses. Our aim was to assess the effect of food intake on ventilatory sensitivity to rising core temperature during exercise. Nine healthy male subjects exercised on a cycle ergometer at 50% of peak oxygen uptake in sessions with and without prior food intake. Ventilatory sensitivity to rising core temperature was defined by the slopes of regression lines relating ventilatory parameters to core temperature. Mean skin temperature, mean body temperature (calculated from esophageal temperature and mean skin temperature), oxygen uptake, carbon dioxide elimination, minute ventilation, alveolar ventilation, and tidal volume (VT) were all significantly higher at baseline in sessions with food intake than without food intake. During exercise, esophageal temperature, mean skin temperature, mean body temperature, carbon dioxide elimination, and end-tidal CO2 pressure were all significantly higher in sessions with food intake than without it. By contrast, ventilatory parameters did not differ between sessions with and without food intake, with the exception of VT during the first 5 min of exercise. The ventilatory sensitivities to rising core temperature also did not differ, with the exception of an early transient effect on VT. Food intake increases body temperature before and during exercise. Other than during the first 5 min of exercise, food intake does not affect ventilatory parameters during exercise, despite elevation of both body temperature and metabolism. Thus, with the exception of an early transient effect on VT, ventilatory sensitivity to rising core temperature is not affected by food intake.

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