scholarly journals Exercise intensity prescription during heat stress: A brief review

2015 ◽  
Vol 25 ◽  
pp. 90-95 ◽  
Author(s):  
J. E. Wingo
Keyword(s):  
Heat Stress ◽  
Exercise Intensity

Exercise intensity regulates the effect of heat stress on substrate oxidation rates during exercise

2019 ◽  
Vol 20 (7) ◽  
pp. 935-943 ◽  
Author(s):  
ED Maunder ◽  
Daniel J. Plews ◽  
Fabrice Merien ◽  
Andrew E. Kilding
Keyword(s):  
Heat Stress ◽  
Exercise Intensity ◽  
Substrate Oxidation ◽  
Oxidation Rates

Influence of heat stress and exercise intensity on vastus lateralis muscle and prefrontal cortex oxygenation

2012 ◽  
Vol 113 (1) ◽  
pp. 211-222 ◽  
Author(s):  
Julien D. Périard ◽  
Martin W. Thompson ◽  
Corinne Caillaud ◽  
Valentina Quaresima
Keyword(s):  
Heat Stress ◽  
Prefrontal Cortex ◽  
Exercise Intensity ◽  
Vastus Lateralis ◽  
Vastus Lateralis Muscle ◽  
Lateralis Muscle

Mechanisms of aerobic performance impairment with heat stress and dehydration

2010 ◽  
Vol 109 (6) ◽  
pp. 1989-1995 ◽  
Author(s):  
Samuel N. Cheuvront ◽  
Robert W. Kenefick ◽  
Scott J. Montain ◽  
Michael N. Sawka
Keyword(s):  
Heat Stress ◽  
Exercise Intensity ◽  
Perceived Exertion ◽  
Muscle Metabolism ◽  
Aerobic Performance ◽  
Exponential Decline ◽  
Relative Exercise Intensity ◽  
Total Body ◽  
Hot Environments ◽  
Cardiovascular Strain

Environmental heat stress can challenge the limits of human cardiovascular and temperature regulation, body fluid balance, and thus aerobic performance. This minireview proposes that the cardiovascular adjustments accompanying high skin temperatures (Tsk), alone or in combination with high core body temperatures (Tc), provide a primary explanation for impaired aerobic exercise performance in warm-hot environments. The independent (Tsk) and combined (Tsk + Tc) effects of hyperthermia reduce maximal oxygen uptake (V̇o2max), which leads to higher relative exercise intensity and an exponential decline in aerobic performance at any given exercise workload. Greater relative exercise intensity increases cardiovascular strain, which is a prominent mediator of rated perceived exertion. As a consequence, incremental or constant-rate exercise is more difficult to sustain (earlier fatigue) or requires a slowing of self-paced exercise to achieve a similar sensation of effort. It is proposed that high Tsk and Tc impair aerobic performance in tandem primarily through elevated cardiovascular strain, rather than a deterioration in central nervous system (CNS) function or skeletal muscle metabolism. Evaporative sweating is the principal means of heat loss in warm-hot environments where sweat losses frequently exceed fluid intakes. When dehydration exceeds 3% of total body water (2% of body mass) then aerobic performance is consistently impaired independent and additive to heat stress. Dehydration augments hyperthermia and plasma volume reductions, which combine to accentuate cardiovascular strain and reduce V̇o2max. Importantly, the negative performance consequences of dehydration worsen as Tsk increases.

Physiological tolerance to uncompensable heat stress: effects of exercise intensity, protective clothing, and climate

1994 ◽  
Vol 77 (1) ◽  
pp. 216-222 ◽  
Author(s):  
S. J. Montain ◽  
M. N. Sawka ◽  
B. S. Cadarette ◽  
M. D. Quigley ◽  
J. M. McKay
Keyword(s):  
Heat Stress ◽  
Relative Humidity ◽  
Core Temperature ◽  
Exercise Intensity ◽  
Protective Clothing ◽  
Heat Exposure ◽  
Heat Strain ◽  
Published Data ◽  
Physiological Tolerance ◽  
Uncompensable Heat Stress

This study determined the influence of exercise intensity, protective clothing level, and climate on physiological tolerance to uncompensable heat stress. It also compared the relationship between core temperature and the incidence of exhaustion from heat strain for persons wearing protective clothing to previously published data of unclothed persons during uncompensable heat stress. Seven heat-acclimated men attempted 180-min treadmill walks at metabolic rates of approximately 425 and 600 W while wearing full (clo = 1.5) or partial (clo = 1.3) protective clothing in both a desert (43 degrees C dry bulb, 20% relative humidity, wind 2.2 m/s) and tropical (35 degrees C dry bulb, 50% relative humidity, wind 2.2 m/s) climate. During these trials, the evaporative cooling required to maintain thermal balance exceeded the maximal evaporative capacity of the environment and core temperature continued to rise until exhaustion from heat strain occurred. Our findings concerning exhaustion from heat strain are 1) full encapsulation in protective clothing reduces physiological tolerance as core temperature at exhaustion was lower (P < 0.05) in fully than in partially clothed persons, 2) partial encapsulation results in physiological tolerance similar to that reported for unclothed persons, 3) raising metabolic rate from 400 to 600 W does not alter physiological tolerance when subjects are fully clothed, and 4) physiological tolerance is similar when subjects are wearing protective clothing in desert and tropical climates having the same wet bulb globe thermometer. These findings can improve occupational safety guidelines for human heat exposure, as they provide further evidence that the incidence of exhaustion from heat strain can be predicted from core temperature.

scholarly journals Plasma Hsp72 (HSPA1A) and Hsp27 (HSPB1) expression under heat stress: influence of exercise intensity

2012 ◽  
Vol 17 (3) ◽  
pp. 375-383 ◽  
Author(s):  
Julien D. Périard ◽  
Patricia Ruell ◽  
Corinne Caillaud ◽  
Martin W. Thompson
Keyword(s):  
Heat Stress ◽  
Exercise Intensity ◽  
Stress Influence

Evaluation of different levels of hydration using a new physiological strain index

1998 ◽  
Vol 275 (3) ◽  
pp. R854-R860 ◽  
Author(s):  
Daniel S. Moran ◽  
Scott J. Montain ◽  
Kent B. Pandolf
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Exercise Intensity ◽  
Esophageal Temperature ◽  
Sweating Rate ◽  
Physiological Strain ◽  
Strain Index ◽  
Hydration Level ◽  
Physiological Strain Index ◽  
Different Levels

A physiological strain index (PSI), based on rectal temperature (Tre) and heart rate (HR), was recently suggested for evaluating heat stress. The purpose of this study was to evaluate the PSI for different combinations of hydration level and exercise intensity. This index was applied to two databases. The first database was obtained from eight endurance-trained men dehydrated to four different levels (1.1, 2.3, 3.4, and 4.2% of body wt) during 120 min of cycling at a power output of 62–67% maximum O2 consumption (V˙o 2 max) in the heat [33°C and 50% relative humidity (RH)]. The second database was obtained from nine men performing exercise in the heat (30°C and 50% RH) for 50 min. These subjects completed a matrix of nine trials of exercise on a treadmill at three exercise intensities (25, 45, and 65%V˙o 2 max) and three hydration levels (euhydration and hypohydration at 3 and 5% of body wt). Tre, HR, esophageal temperature (Tes), and local sweating rate were measured. PSI (obtained from either Tre or Tes) significantly ( P < 0.05) differentiated among all exposures in both databases categorized by exercise intensity and hydration level, and we assessed the strain on a scale ranging from 0 to 10. Therefore, PSI applicability was extended for heat strain associated with hypohydration and continues to provide the potential to be universally accepted.

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