scholarly journals Influence of aerobic fitness on gastrointestinal barrier integrity and microbial translocation following a fixed-intensity military exertional heat stress test

2020 ◽  
Vol 120 (10) ◽  
pp. 2325-2337
Author(s):  
Henry B. Ogden ◽  
Joanne L. Fallowfield ◽  
Robert B. Child ◽  
Glen Davison ◽  
Simon C. Fleming ◽  
...  
Keyword(s):  
Heat Stress ◽  
Aerobic Fitness ◽  
Stress Test ◽  
Microbial Translocation ◽  
Barrier Integrity ◽  
Gastrointestinal Barrier ◽  
Exertional Heat Stress

scholarly journals Reliability of gastrointestinal barrier integrity and microbial translocation biomarkers at rest and following exertional heat stress

2020 ◽  
Vol 8 (5) ◽  
Author(s):  
Henry B. Ogden ◽  
Joanne L. Fallowfield ◽  
Robert B. Child ◽  
Glen Davison ◽  
Simon C. Fleming ◽  
...  
Keyword(s):  
Heat Stress ◽  
Microbial Translocation ◽  
Barrier Integrity ◽  
Gastrointestinal Barrier ◽  
Exertional Heat Stress

scholarly journals The Gastrointestinal Exertional Heat Stroke Paradigm: Pathophysiology, Assessment, Severity, Aetiology and Nutritional Countermeasures

Nutrients ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 537 ◽  
Author(s):  
Henry B. Ogden ◽  
Robert B. Child ◽  
Joanne L. Fallowfield ◽  
Simon K. Delves ◽  
Caroline S. Westwood ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Stroke ◽  
Thermal Strain ◽  
Microbial Translocation ◽  
Molecular Probe ◽  
Strenuous Exercise ◽  
Management Approach ◽  
Exertional Heat Stroke ◽  
Barrier Integrity ◽  
Exertional Heat Stress

Exertional heat stroke (EHS) is a life-threatening medical condition involving thermoregulatory failure and is the most severe condition along a continuum of heat-related illnesses. Current EHS policy guidance principally advocates a thermoregulatory management approach, despite growing recognition that gastrointestinal (GI) microbial translocation contributes to disease pathophysiology. Contemporary research has focused to understand the relevance of GI barrier integrity and strategies to maintain it during periods of exertional-heat stress. GI barrier integrity can be assessed non-invasively using a variety of in vivo techniques, including active inert mixed-weight molecular probe recovery tests and passive biomarkers indicative of GI structural integrity loss or microbial translocation. Strenuous exercise is strongly characterised to disrupt GI barrier integrity, and aspects of this response correlate with the corresponding magnitude of thermal strain. The aetiology of GI barrier integrity loss following exertional-heat stress is poorly understood, though may directly relate to localised hyperthermia, splanchnic hypoperfusion-mediated ischemic injury, and neuroendocrine-immune alterations. Nutritional countermeasures to maintain GI barrier integrity following exertional-heat stress provide a promising approach to mitigate EHS. The focus of this review is to evaluate: (1) the GI paradigm of exertional heat stroke; (2) techniques to assess GI barrier integrity; (3) typical GI barrier integrity responses to exertional-heat stress; (4) the aetiology of GI barrier integrity loss following exertional-heat stress; and (5) nutritional countermeasures to maintain GI barrier integrity in response to exertional-heat stress.

scholarly journals Relationship between heat storage and parameters of thermotolerance and fatigue in exertional-heat stress

2021 ◽  
pp. 99-99
Author(s):  
Sinisa Masic ◽  
Sonja Marjanovic ◽  
Jelena Maric ◽  
Vanja Jovanovic ◽  
Mirjana Joksimovic ◽  
...  
Keyword(s):  
Heat Stress ◽  
Perceived Exertion ◽  
Heat Storage ◽  
Stress Test ◽  
Physiological Strain ◽  
Blood Concentrations ◽  
Fatigue Development ◽  
The Relationship ◽  
Exertional Heat Stress ◽  
Peripheral Markers

Background/Aim. The risk assessment of heat illness and fatigue development is very important in military services. the aim of our study was to investigate the relationship between heat storage and various psychophysiological parameters of heat stress, as well as potential peripheral markers of fatigue in soldiers performing exertional heat stress test. Methods. 15 young, healthy and unacclimatized men underwent exertional heat stress test (EHST) with submaximal work load in warm conditions (WBGT 29 ?C) in climatic chamber. Every 5 minutes following parameters of thermotolerance were measured or calculated: core temperature (Tc), mean skin (Tsk) and body temperature (Tb), heart rate (HR), heat storage (HS), physiological strain index (PSI), as well as peripheral markers of fatigue (blood concentrations of ammonia, urea nitrogen (BUN), lactate dehydrogenase (LDH), cortisol and prolactin) and subjective parameters: thermal sensation (TS) and rate of perceived exertion (RPE). Results. Tolerance time varied from 45-75 minutes (63?7,7 min). Average values of Tc, Tb, and HR constantly increased during EHST, while Tsk after 10 minutes reached the plateau. Concentrations of all investigated peripheral markers of fatigue were significantly higher after EHST compared to baseline levels (31,47?7,29 vs. 11,8?1,11 ?mol/l for ammonia; 5,92?0,73 vs. 4,69?0,74 mmol/l for BUN, 187,27?28,49 vs.152,73?23,39 U/l for LDH, 743,43?206,19 vs. 558,79?113,34 mmol/l for cortisol and 418,08?157,14 vs. 138,79?92,83 ?IU/mL for prolactin). Conclusions. This study demonstrates the relationship between heat storage and Tc, HR, TS and RPE, but also with PSI. Concentrations of cortisol and especially prolactin showed significant correlation with parameters of thermotolerance.

scholarly journals The influence of the passive evaporative cooling vest on a chemical industry workers and physiological strain level in hot conditions

2015 ◽  
Vol 69 (6) ◽  
pp. 587-594 ◽  
Author(s):  
Radovan Karkalic ◽  
Dalibor Jovanovic ◽  
Sonja Radakovic ◽  
Dusan Rajic ◽  
Biljana Petrovic ◽  
...  
Keyword(s):  
Heat Stress ◽  
Cooling System ◽  
Sweat Rate ◽  
Stress Test ◽  
Tympanic Temperature ◽  
Physiological Strain ◽  
Military Medical Academy ◽  
Hot Environment ◽  
Body Cooling ◽  
Exertional Heat Stress

The present study was conducted in order to evaluate efficiency of a personal body cooling system based on passive evaporative technologies and its effects on test subjects psycho-physiological suitability during exertional heat stress in hot environment. Performed results are based on conducted tests in climatic chamber in the Military Medical Academy Institute of Hygiene in Belgrade. Ten male test subjects were subjected to exertional heat stress test consisted of walking on motorized treadmill at a speed of 5 km/h in hot environment. Tests were performed with and without cooling system. As a physiological strain indicator the following parameters have been determined: mean skin temperature, tympanic temperature, heart rate and sweat rate. Results confirmed that cooling vest worn over the clothes was able to attenuate the physiological strain levels during exercise, when compared to identical exposure without the cooling system.

scholarly journals The effects of acclimatization on blood clotting parameters in exertional heat stress

2013 ◽  
Vol 70 (7) ◽  
pp. 670-674 ◽  
Author(s):  
Zoran Vesic ◽  
Milica Vukasinovic-Vesic ◽  
Dragan Dincic ◽  
Maja Surbatovic ◽  
Sonja Radakovic
Keyword(s):  
Heat Stress ◽  
Prothrombin Time ◽  
Blood Clotting ◽  
Stress Test ◽  
Heat Stroke ◽  
Climatic Chamber ◽  
Physiological Strain ◽  
Platelet Counts ◽  
Globe Temperature ◽  
Exertional Heat Stress

Background/Aim. Exertional heat stress is a common problem in military services. Considering the coagulation abnormalities are of major importance in development of severe heat stroke, we wanted to examine changes in hemostatic parameters in soldiers during exertional heat stress test as well as the effects of a 10-day passive or active acclimatization in a climatic chamber. Methods. A total of 40 male soldiers with high aerobic capacity performed exertional heat stress test (EHST) either in cool [20?C, 16?C wet bulb globe temperature (WBGT)], or hot (40?C, 29?C, (WBGT) environment, unacclimatized (U) or after 10 days of passive (P) or active (A) acclimatization. Physiological strain was measured by tympanic temperatures (Tty) and heart rates (HR). Platelet count (PC), antithrombin III (AT), and prothrombin time (PT) were assessed in blood samples collected before and immediately after the EHST. Results. EHST in hot conditions induced physiological heat stress (increase in Tty and HR), with a significant increase in prothrombin time in the groups U and A. Platelet counts were significantly higher after the EHST compared to the basic levels in all the investigated groups, regardless environmental conditions and acclimatization state. Antithrombin levels were not affected by EHST whatsoever. Conclusion. In the trained soldiers, physiological heat stress caused mild changes in some serum parameters of blood clotting such as prothrombin time, while others such as antithrombin levels were not affected. Platelet counts were increased after EHST in all groups. A 10-day passive or active acclimatization in climatic chamber showed no effect on parameters investigated.

scholarly journals Short-term dietary curcumin supplementation reduces gastrointestinal barrier damage and physiological strain responses during exertional heat stress

2018 ◽  
Vol 124 (2) ◽  
pp. 330-340 ◽  
Author(s):  
Mandy C. Szymanski ◽  
Trevor L. Gillum ◽  
Lacey M. Gould ◽  
David S. Morin ◽  
Matthew R. Kuennen
Keyword(s):  
Heat Stress ◽  
Barrier Function ◽  
Repeated Measures ◽  
Interleukin 1 ◽  
Interleukin 10 ◽  
Physiological Strain ◽  
Fatty Acid Binding ◽  
Tnf Α ◽  
Gastrointestinal Barrier ◽  
Exertional Heat Stress

This work investigated the effect of 3 days of 500 mg/day dietary curcumin supplementation on gastrointestinal barrier damage and systems-physiology responses to exertional heat stress in non-heat-acclimated humans. Eight participants ran (65% V̇o2max) for 60 min in a Darwin chamber (37°C/25% relative humidity) two times (Curcumin/Placebo). Intestinal fatty acid-binding protein (I-FABP) and associated proinflammatory [monocyte chemoattractant protein-1, tumor necrosis factor-α (TNF-α), interleukin-6] and anti-inflammatory [interleukin-1 receptor antagonist (IL-1RA), interleukin-10 (IL-10)] cytokines were assayed from plasma collected before (Pre), after (Post) and 1 (1-Post) and 4 (4-Post) h after exercise. Core temperature and HR were measured throughout exercise; the physiological strain index (PSI) was calculated from these variables. Condition differences were determined with 2-way (condition × time) repeated-measures ANOVAs. The interaction of condition × time was significant ( P = 0.05) for I-FABP and IL-1RA. Post hoc analysis indicated I-FABP increased more from Pre to Post (87%) and 1-Post (33%) in Placebo than in Curcumin (58 and 18%, respectively). IL-1RA increased more from Pre to 1-Post in Placebo (153%) than in Curcumin (77%). TNF-α increased ( P = 0.01) from Pre to Post (19%) and 1-Post (24%) in Placebo but not in Curcumin ( P > 0.05). IL-10 increased ( P < 0.01) from Pre to Post (61%) and 1-Post (42%) in Placebo not in Curcumin ( P > 0.05). The PSI, which indicates exertional heatstroke risk, was also lower ( P < 0.01) in Curcumin than Placebo from 40 to 60 min of exercise. These data suggest 3 days curcumin supplementation may improve gastrointestinal function, associated cytokines, and systems-level physiology responses during exertional heat stress. This could help reduce exertional heatstroke risk in non-heat-acclimated individuals.NEW & NOTEWORTHY Exercise-heat stress increases gastrointestinal barrier damage and risk of exertional heatstroke. Over the past decade at least eight different dietary supplements have been tested for potential improvements in gastrointestinal barrier function and systems-level physiology responses during exercise-heat stress. None have been shown to protect against both insults simultaneously. In this report 3 days of 500 mg/day dietary curcumin supplementation are shown to improve gastrointestinal barrier function, associated cytokine responses, and systems-level physiology parameters. Further research is warranted.

scholarly journals Influence of acclimatization on serum enzyme changes in soldiers during exertional heat stress

2009 ◽  
Vol 66 (5) ◽  
pp. 359-364 ◽  
Author(s):  
Sonja Radakovic ◽  
Jelena Maric ◽  
Maja Surbatovic ◽  
Nadja Vasiljevic ◽  
Mladen Milivojevic
Keyword(s):  
Heat Stress ◽  
Stress Test ◽  
Serum Concentrations ◽  
Climatic Chamber ◽  
Physiological Strain ◽  
Physical Strain ◽  
Stress Increase ◽  
Wet Bulb Globe Temperature ◽  
Globe Temperature ◽  
Exertional Heat Stress

Background/Aim. Exertional heat stress is common problem in military services. The aim was to examine changes in serum concentrations of some enzymes in soldiers during exertional heat stress test (EHST) as well as the effects of 10-days passive or active acclimatization in climatic chamber. Methods. Forty male soldiers with high aerobic capacity, performed EHST either in cool (20 ?C, 16 ?C Wet bulb globe temperature - WBGT), or hot (40 ?C, 25 ?C WBGT) environment, unacclimatized, or after 10 days of passive or active acclimation. Physiological strain was measured by tympanic temperatures (Tty) and heart rates (HR). Concentrations of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine-kinase (CK) were measured in blood samples collected before and immediately after EHST. Results. Exertional heat stress test in hot conditions induced physiological heat stress (increase in Tty and HR), with significant increase in concentrations of all enzymes in unacclimatized group: ALT (42.5 ? 4.2 before vs 48.1 ? 3.75 U/L after EHST, p < 0.01), AST (24.9 ? 5.1 vs 33.4 ? 4.48 U/L, p < 0.01), LDH (160.6 ? 20.2 vs 195.7 ? 22.6 U/L, p < 0.001) and CK (215.5 ? 91.2 vs 279.1 ? 117.5 U/L, p < 0.05). In acclimatized soldiers there were no significant changes in concentrations of ALT and AST, while concentration of CK was significantly higher. Concentrations of LDH were significantly higher in all investigated groups, regardless of temperature conditions. Conclusion. In trained soldiers, 10-days passive or active acclimatization in climatic chamber can prevent increase in serum concentrations of ALT and AST, induced by exertional heat stress. Increase of serum concentrations of CK and LDH was induced by physical strain itself, with no additional effect of heat stress.

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