Cardiovascular Response To Short-Duration Hard Work In High and Low Heat Stress Environments

1998 ◽  
Vol 30 (Supplement) ◽  
pp. 282
Author(s):  
M. D. Becque ◽  
P. Linn
Keyword(s):  
Heat Stress ◽  
Short Duration ◽  
Cardiovascular Response ◽  
Hard Work ◽  
Stress Environments

Thermoregulatory, cardiovascular, and psychophysical response to alcohol in men in 40 degrees C water

1992 ◽  
Vol 72 (6) ◽  
pp. 2099-2107 ◽  
Author(s):  
T. G. Allison ◽  
W. E. Reger
Keyword(s):  
Heat Stress ◽  
Sweat Rate ◽  
Cardiovascular Response ◽  
Water Immersion ◽  
Rate Pressure Product ◽  
Esophageal Temperature ◽  
Healthy Men ◽  
Cardiovascular Stress ◽  
Rate Of Increase ◽  
Normal Relationship

The goals of the study were to test the hypotheses that ethyl alcohol (ETOH) in low-to-moderate doses would alter thermo-regulation and/or disrupt the normal relationship between physiological and psychophysical indexes of heat stress during 40 degrees C water immersion and to characterize the cardiovascular response to the combined stimuli of heat, water immersion, and ETOH. Six healthy men underwent three trials of 21 min of immersion in water at 40.0 +/- 0.1 degrees C after consuming 0, 0.27, or 0.54 g ETOH/kg. Esophageal temperature (Tes) rose by approximately 1.0 degrees C during immersion for each trial. Per unit of Tes rise, changes during immersion in skin temperature, sweat rate, heart rate, systolic and diastolic blood pressure, and psychophysical assessments of comfort and overheating did not differ significantly by trial. Across trials, there was an apparent threshold for activation of thermoregulatory responses at an approximately 0.5 degrees C increase in Tes occurring after approximately 9 min of immersion. This threshold was identified psychophysically by increased ratings of overheating and decreased comfort. Above the threshold, there was an attenuation of the rate of increase of Tes. Cardiovascular stress was mild (rate-pressure product approximately 12,000) and not significantly increased by ETOH. Hypotension and tachycardia when subjects stood to exit the tub were observed. The data suggest that ETOH at the doses administered does not affect thermoregulatory, cardiovascular, or psychophysical indexes of heat stress during 40 degrees C water immersion.

Stability of Heart Rate at Physiological Thresholds Between Temperate and Heat Stress Environments in Endurance-Trained Males

2020 ◽  
pp. 1-4
Author(s):  
Ed Maunder ◽  
Daniel J. Plews ◽  
Fabrice Merien ◽  
Andrew E. Kilding
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Relative Humidity ◽  
Blood Lactate ◽  
Endurance Athletes ◽  
Heart Rates ◽  
Stress Environments ◽  
Positive Correlations ◽  
Hot Environments ◽  
Stress Training

Many endurance athletes perform specific blocks of training in hot environments in “heat stress training camps.” It is not known if physiological threshold heart rates measured in temperate conditions are reflective of those under moderate environmental heat stress. A total of 16 endurance-trained cyclists and triathletes performed incremental exercise assessments in 18°C and 35°C (both 60% relative humidity) to determine heart rates at absolute blood lactate and ventilatory thresholds. Heart rate at fixed blood lactate concentrations of 2, 3, and 4 mmol·L−1 and ventilatory thresholds were not significantly different between environments (P > .05), despite significant heat stress-induced reductions in power output of approximately 10% to 17% (P < .05, effect size = 0.65–1.15). The coefficient of variation for heart rate at these blood lactate concentrations (1.4%−2.9%) and ventilatory thresholds (2.3%−2.7%) between conditions was low, with significant strong positive correlations between measurements in the 2 environments (r = .92–.95, P < .05). These data indicate heart rates measured at physiological thresholds in temperate environments are reflective of measurements taken under moderate environmental heat stress. Therefore, endurance athletes embarking on heat stress training camps can use heart rate–based thresholds ascertained in temperate environments to prescribe training under moderate environmental heat stress.

Raising productivity of cereal crops in dry and heat stress environments remains a breeding challenge.

2021 ◽  
Vol 16 (008) ◽  
Author(s):  
Sangam L. Dwivedi
Keyword(s):  
Heat Stress ◽  
Agricultural Production ◽  
Green Revolution ◽  
Cereal Crops ◽  
Plant Genes ◽  
Stress Environments

Abstract 'Green Revolution' genes have led to the release of input-responsive cultivars, resulting in multifold productivity increases in rice and wheat. Declining precipitation, increased intensity of drought and rising temperature are casting uncertainty over agricultural production. As noted in this mini review, plant genes when over-expressed allow cereals to produce grains in drought- and heat-prone sites.

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.

scholarly journals Fifty years of semi-dwarf spring wheat breeding at CIMMYT: Grain yield progress in optimum, drought and heat stress environments

2020 ◽  
Vol 250 ◽  
pp. 107757 ◽  
Author(s):  
Suchismita Mondal ◽  
Somak Dutta ◽  
Leonardo Crespo-Herrera ◽  
Julio Huerta-Espino ◽  
Hans J. Braun ◽  
...  
Keyword(s):  
Heat Stress ◽  
Grain Yield ◽  
Spring Wheat ◽  
Wheat Breeding ◽  
Stress Environments ◽  
Drought And Heat Stress

Performance of Yield and Stability of Advanced Wheat Genotypes under Heat Stress Environments of the Indo-Gangetic Plains

Crop Science ◽  
2007 ◽  
Vol 47 (4) ◽  
pp. 1561-1573 ◽  
Author(s):  
Jagadish Rane ◽  
Raj Kumar Pannu ◽  
Virinder Singh Sohu ◽  
Ran Singh Saini ◽  
Banwari Mishra ◽  
...  
Keyword(s):  
Heat Stress ◽  
Gangetic Plains ◽  
Wheat Genotypes ◽  
Stress Environments

Reduced Tolerance for Heat Stress Environments Caused by Protective Lotions.

AIHAJ ◽  
1985 ◽  
Vol 46 (8) ◽  
pp. 460-462 ◽  
Author(s):  
WIL A. SPAUL ◽  
J. ALLEN BOATMAN ◽  
STEVE W. EMLING ◽  
H. GENE DIRKS ◽  
SKIP B. FLOHR ◽  
...  
Keyword(s):  
Heat Stress ◽  
Stress Environments

Cardiovascular control during heat stress in older adults: time for an update

2020 ◽  
Author(s):  
Hugo Gravel ◽  
Georgia K Chaseling ◽  
Hadiatou Barry ◽  
Amelie Debray ◽  
Daniel Gagnon
Keyword(s):  
Older Adults ◽  
Cardiac Output ◽  
Heat Stress ◽  
Stroke Volume ◽  
Cardiovascular Response ◽  
Heat Exposure ◽  
Extreme Heat Events ◽  
Risk Of Mortality ◽  
Increased Risk ◽  
Aged Skin

It is generally accepted that older adults display an impaired cardiovascular response to heat stress, and it has been suggested that this impaired response contributes to their increased risk of mortality during extreme heat events. Seminal studies have shown that cutaneous vasodilation, the redistribution of blood flow from visceral organs and the increase in cardiac output are blunted in older adults during passive heating. The blunted rise of cardiac output was initially attributed to an inability to maintain stroke volume, suggesting that cardiac systolic and/or diastolic function does not adequately respond to the constraints of heat stress in older adults. Recent studies evaluated potential mechanisms underlying these seminal findings and their results challenge some of these initial observations. Notably, stroke volume is maintained during heat exposure in older adults and studies have provided evidence for preserved cardiac systolic and diastolic functions in this population. Nonetheless, a blunted increase in cardiac output during heat exposure remains a consistent observation in older adults although it is now attributed to a blunted increase in heart rate. Recent studies have also evaluated the possibility that the attenuated capacity of aged skin to vasodilate contributes to a blunted increase in cardiac output during heat stress. The objective of this Mini-Review is to highlight these recent advances and challenge the longstanding view that the control of stroke volume during heat exposure is compromised in older adults. By doing so, our intent is to stimulate future studies to evaluate several unanswered questions in this area of research.

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