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 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 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.

scholarly journals Effects of an antiandrogenic oral contraceptive pill compared with metformin on blood coagulation tests and endothelial function in women with the polycystic ovary syndrome: influence of obesity and smoking

2009 ◽  
Vol 160 (3) ◽  
pp. 469-480 ◽  
Author(s):  
Manuel Luque-Ramírez ◽  
Covandonga Mendieta-Azcona ◽  
José M del Rey Sánchez ◽  
Milagro Matíes ◽  
Héctor F Escobar-Morreale
Keyword(s):  
Oral Contraceptive ◽  
Polycystic Ovary Syndrome ◽  
Endothelial Function ◽  
Prothrombin Time ◽  
Blood Clotting ◽  
Polycystic Ovary ◽  
Oral Contraceptive Pill ◽  
Ovary Syndrome ◽  
Prothrombin Activity ◽  
Platelet Counts

ObjectiveTo study the blood clotting tests and endothelial function of polycystic ovary syndrome (PCOS) patients and non-hyperandrogenic women, and their changes during PCOS treatment, as a function of the presence of obesity and smoking.DesignCase-control study followed by a randomized clinical trial.MethodsBlood clotting and endothelial function were analyzed in 40 PCOS patients and 20 non-hyperandrogenic women. Thirty-four PCOS women were randomized to an oral contraceptive containing 35 μg ethinyl-estradiol plus 2 mg cyproterone acetate (Diane35Diario) or metformin (850 mg twice daily), monitoring the changes on these parameters during 24 weeks of treatment. The influence of obesity and smoking was also analyzed.ResultsBlood clotting and endothelial function tests were similar among PCOS patients and controls with the exception of a higher platelet count in the former. Obesity increased circulating fibrinogen levels, prothrombin activity and platelet counts, and reduced prothrombin and activated partial thromboplastin times. Smoking increased fibrinogen levels, platelet counts, and prothrombin activity, and reduced prothrombin time, in relation to the larger waist circumference of smokers. Irrespective of the treatment received, PCOS patients showed a decrease in prothrombin time and an increase in prothrombin activity, with a parallel increase in homocysteine levels in metformin users. The activated partial thromboplastin time decreased markedly in the patients treated with Diane35Diario. Finally, flow-mediated dilation improved in non-smokers irrespective of the drug received, but worsened in smokers.ConclusionsOral contraceptives and metformin may exert deleterious effects on blood clotting tests of PCOS women, yet the effects of metformin appear to be milder. Because smoking potentiates some of these effects and deteriorates endothelial function, smoking cessation should be promoted in PCOS patients.

scholarly journals Mild endotoxemia, NF-κB translocation, and cytokine increase during exertional heat stress in trained and untrained individuals

2008 ◽  
Vol 295 (2) ◽  
pp. R611-R623 ◽  
Author(s):  
G. A. Selkirk ◽  
T. M. McLellan ◽  
H. E. Wright ◽  
S. G. Rhind
Keyword(s):  
Heat Stress ◽  
Lean Body Mass ◽  
Body Mass ◽  
Venous Blood ◽  
Heat Stroke ◽  
Killer Cell ◽  
Endotoxin Tolerance ◽  
C 30 ◽  
Exertional Heat Stress

This study examined endotoxin-mediated cytokinemia during exertional heat stress (EHS). Subjects were divided into trained [TR; n = 12, peak aerobic power (V̇o2peak) = 70 ± 2 ml·kg lean body mass−1·min−1] and untrained (UT; n = 11, V̇o2peak= 50 ± 1 ml·kg lean body mass−1·min−1) groups before walking at 4.5 km/h with 2% elevation in a climatic chamber (40°C, 30% relative humidity) wearing protective clothing until exhaustion (Exh). Venous blood samples at baseline and 0.5°C rectal temperature increments (38.0, 38.5, 39.0, 39.5, and 40.0°C/Exh) were analyzed for endotoxin, lipopolysaccharide binding protein, circulating cytokines, and intranuclear NF-κB translocation. Baseline and Exh samples were also stimulated with LPS (100 ng/ml) and cultured in vitro in a 37°C water bath for 30 min. Phenotypic determination of natural killer cell frequency was also determined. Enhanced blood (104 ± 6 vs. 84 ± 3 ml/kg) and plasma volumes (64 ± 4 vs. 51 ± 2 ml/kg) were observed in TR compared with UT subjects. EHS produced an increased concentration of circulating endotoxin in both TR (8 ± 2 pg/ml) and UT subjects (15 ± 3 pg/ml) (range: not detected to 32 pg/ml), corresponding with NF-κB translocation and cytokine increases in both groups. In addition, circulating levels of tumor necrosis factor-α and IL-6 were also elevated combined with concomitant increases in IL-1 receptor antagonist in both groups and IL-10 in TR subjects only. Findings suggest that the threshold for endotoxin leakage and inflammatory activation during EHS occurs at a lower temperature in UT compared with TR subjects and support the endotoxin translocation hypothesis of exertional heat stroke, linking endotoxin tolerance and heat tolerance.

Thermal and circulatory responses during exercise: effects of hypohydration, dehydration, and water intake

1997 ◽  
Vol 82 (6) ◽  
pp. 2028-2035 ◽  
Author(s):  
Lawrence E. Armstrong ◽  
Carl M. Maresh ◽  
Catherine V. Gabaree ◽  
Jay R. Hoffman ◽  
Stavros A. Kavouras ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Water Intake ◽  
Rectal Temperature ◽  
Stress Test ◽  
Plasma Osmolality ◽  
Interactive Effects ◽  
Stress Tests ◽  
Physiological Strain ◽  
Exercise Induced

Armstrong, Lawrence E., Carl M. Maresh, Catherine V. Gabaree, Jay R. Hoffman, Stavros A. Kavouras, Robert W. Kenefick, John W. Castellani, and Lynn E. Ahlquist. Thermal and circulatory responses during exercise: effects of hypohydration, dehydration, and water intake. J. Appl. Physiol. 82(6): 2028–2035, 1997.—This investigation examined the distinct and interactive effects of initial hydration state, exercise-induced dehydration, and water rehydration in a hot environment. On four occasions, 10 men performed a 90-min heat stress test (treadmill walking at 5.6 km/h, 5% grade, 33°C, 56% relative humidity). These heat stress tests differed in pretest hydration [2 euhydrated (EU) and 2 hypohydrated (HY) trials] and water intake during exercise [2 water ad libitum (W) and 2 no water (NW) trials]. HY + NW indicated greater physiological strain than all other trials ( P < 0.05–0.001) in heart rate, plasma osmolality (Posm), sweat sensitivity (g / °C ⋅ min), and rectal temperature. Unexpectedly, final HY + W and EU + W responses for rectal temperature, heart rate, and Posm were similar, despite the initial 3.9 ± 0.2% hypohydration in HY + W. We concluded that differences in pretest Posm (295 ± 7 and 287 ± 5 mosmol/kg for HY + W and EU + W, respectively) resulted in greater water consumption (1.65 and 0.31 liter for HY + W and EU + W, respectively), no voluntary dehydration (0.9% body mass increase), and attenuated thermal and circulatory strain during HY + W.

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