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.

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 Effects of acclimation on water and electrolitic disbalance in soldiers during exertional heat stress

2007 ◽  
Vol 64 (3) ◽  
pp. 199-204 ◽  
Author(s):  
Sonja Radakovic ◽  
Jelena Maric ◽  
Velimir Rubezic ◽  
Maja Surbatovic ◽  
Slavica Radjen
Keyword(s):  
Heat Stress ◽  
Serum Sodium ◽  
Sweat Rate ◽  
Tap Water ◽  
Sodium Concentration ◽  
Serum Concentrations ◽  
Climatic Chamber ◽  
Physiological Strain ◽  
Globe Temperature ◽  
Exertional Heat Stress

Background/Aim. Exertional heat stress is a common problem in military services. The aim of this study was to examine changes in body water and serum concentrations of some electrolites in soldiers during exertional heat stress (EHST), as well as effects of 10-day passive or active acclimation in a climatic chamber. Methods. Forty male soldiers with high aerobic capacity, performed EHST either in cool (20 ?C, 16 ?C WBGT-wet bulb globe temperature), or hot (40 ?C, 25 ?C WBGT) environment, unacclimatized, or after 10 days of passive or active acclimation. The subjects were allowed to drink tap water ad libitum during EHST. Mean skin (Tsk) and tympanic (Tty) temperatures and heart rates (HR) measured physiological strain, while sweat rate (SwR), and serum concentrations of sodium, potassium and osmolality measured changes in water and electrolyte status. Blood samples were collected before and immediately after the EHST. Results. Exertional heat stress in hot conditions induced physiological heat stress (increase in Tty, HR, and SwR), with significant decrease in serum sodium concentration (140.6?1.52 before vs 138.5?1.0 mmol/l after EHST, p < 0.01) and osmolality (280.7?3.8 vs 277.5?2.6 mOsm/kg, p < 0.05) in the unacclimatized group. The acclimated soldiers suffered no such effects of exertional heat stress, despite almost the same degree of heat strain, measured by Tty, HR and SwR. Conclusion. In the trained soldiers, 10-day passive or active acclimation in a climatic chamber can prevent disturbances in water and electrolytic balance, i.e. decrease in serum sodium concentrations and osmolality induced by 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 Efficacy of a novel phase change material for microclimate body cooling

2014 ◽  
Vol 18 (2) ◽  
pp. 657-665 ◽  
Author(s):  
Dalibor Jovanovic ◽  
Radovan Karkalic ◽  
Ljubisa Tomic ◽  
Zlate Velickovic ◽  
Sonja Radakovic
Keyword(s):  
Heat Stress ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Imaging ◽  
Cooling System ◽  
Control Group ◽  
Climatic Chamber ◽  
Physiological Strain ◽  
Exertional Heat Stress ◽  
Change Material

The present study was conducted in order to evaluate the efficiency of personal body microclimate cooling systems based on a phase change materials (PCM) and its effects on physiological strain in soldiers during exertional heat stress in hot environment. The results are obtained in the experiment conducted in the climatic chamber in the Institute of Hygiene, Military Medical Academy in Belgrade. Ten male soldiers were voluntarily subjected to exertional heat stress tests (EHST) consisted of walking on treadmill (5.5 km/h) in hot conditions (40?C) in climatic chamber. The subjects performed first test while wearing a field camouflage uniform without any cooling system ("CONTROL" group) and in second test they used additional microclimate cooling system with paraffin wax consist of n-hexadecane (C16H34), in a form of cooling packs ("COOL" group). As indicators of thermal strain, mean skin (Tsk) and tympanic (Tty) temperature were determined. Simultaneously, thermal effects of PCM were measured by thermal imaging camera. The exercise in hot conditions induced a physiological response to heat stress, manifested through increased body core and skin temperatures. The results confirmed that the cooling vest worn over the field uniform was able to attenuate the physiological strain during exercise, compared to the identical exposure in the ''control'' group. The results of thermal imaging also indicate that heat generated inside the body is the main factor that will affect the phase change material melting time.

On the use of wearable physiological monitors to assess heat strain during occupational heat stress

2018 ◽  
Vol 43 (9) ◽  
pp. 869-881 ◽  
Author(s):  
Sean R. Notley ◽  
Andreas D. Flouris ◽  
Glen P. Kenny
Keyword(s):  
Heat Stress ◽  
High Heat ◽  
Heat Strain ◽  
Individual Factors ◽  
Physiological Strain ◽  
Heat Injury ◽  
Wet Bulb Globe Temperature ◽  
Work Related ◽  
Physiological Indices ◽  
Globe Temperature

Workers in many industries are required to perform arduous work in high heat-stress conditions, which can lead to rapid increases in body temperature that elevate the risk of heat-related illness and even death. Traditionally, effort to mitigate work-related heat injury has been directed toward the assessment of environmental heat stress (e.g., wet-bulb globe temperature), rather than toward the associated physiological strain responses (e.g., heart rate and skin and core temperatures). However, because a worker’s physiological response to a given heat stress is modified independently by inter-individual factors (e.g., age, sex, chronic disease, others) and intra-individual factors both within (e.g., medication use, fitness, acclimation and hydration state, others) and beyond (e.g., shift duration, illness, others) the worker’s control, it becomes challenging to protect workers on an individual basis from heat-related injury without assessing those physiological responses. Recent advancements in wearable technology have made it possible to monitor one or more physiological indices of heat strain. Nonetheless, information on the utility of the wearable systems available for assessing occupational heat strain is unavailable. This communication is therefore directed toward identifying the physiological indices of heat strain that may be quantified in the workplace and evaluating the wearable monitoring systems available for assessing those responses. Finally, emphasis is placed on the barriers associated with implementing these devices to assist in mitigating work-related heat injury. This information is fundamental for protecting worker health and could also be utilized to prevent heat illnesses in vulnerable people during leisure or athletic activities.

EFFECTS OF INONIZING RADIATION CAUSED HEAT STRESS ON THE HUMAN BODY FOR STANDARD ISO 7243

2013 ◽  
pp. 47-57
Author(s):  
Van Trong Le ◽  
Thi Tuyet Mai Nguyen ◽  
Thi Xuan Duyen Nguyen ◽  
Ba Luan Nguyen ◽  
Tuyen Pham ◽  
...  
Keyword(s):  
Heat Stress ◽  
Risk Assessments ◽  
Management Systems ◽  
Temperature Index ◽  
Wet Bulb Globe Temperature ◽  
Simple Index ◽  
Simple Tool ◽  
Results Management ◽  
Globe Temperature ◽  
Hot Environments

Objectives: Presents heat stress Standard ISO 7243, which is based upon the wet bulb globe temperature index (WBGT), and considers its suitability for use worldwide. Materials and Methods: The WBGT index are considered and how it is used in ISO 7243 and across the world as a simple index for monitoring and assessing hot environments. Results: Management systems, involving risk assessments, that take account of context and culture, are required to ensure successful use of the standard and global applicability. For use outdoors, a WBGT equation that includes solar absorptivity is recommended. A ‘clothed WBGT’ is proposed to account for the effects of clothing. Conclusion: ISO 7243 is a simple tool to assess the heat stress and may be applicated worldwide.

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