Investigation of the effect of acclimation on the concentration of stress hormones and hemostatic factors in serum of soldiers exposed to heat stress in physical activity

Cilj ove studije je bio da ispita toleranciju na toplotni stres usled fizičkog napora u grupama ispitanika podvrgnutih fizičkom naporu koji su prethodno izloženi pasivnoj, odnosno aktivnoj aklimatizaciji, kao i da utvrdi uticaj aklimatizacije na fizičku sposobnost i funkcije hormonskog, enzimskog i hemostatskog sistema. Metode. Ispitivanjem je obuhvaćeno ukupno 40 muškaraca, studenata iste klase Vojne Akademije u Beogradu, odsek KOV, starosti od 19-21 godine, podeljenih metodom slučajnog izbora prema tablicama slučajnih brojeva u 4 grupe (K, 0, P i A grupa). Ispitanici iz K grupe su podvrgnuti testu termotolerancije u komfornim uslovima, uz submaksimalno fizičko opterećenje; iz 0 grupe podvrgnuti su istom testu u uslovima tople sredine, P grupa se prethodno izlaže pasivnoj 10-dnevnoj aklimatizaciji, a A grupa aktivnoj aklimatizaciji istog trajanja. Ispitivanje antropometrijskih i ergometrijskih karakteristika obuhvatilo je: merenje telesne visine (cm), telesne mase (kg), uhranjenosti i sadržaja telesne masti. Ergometrijske karakteristike (VO2max) ispitivane su indirektno, preko pulsa, metodom po Brusu, uz korišćenje pokretne trake. Svakom ispitaniku je u dva navrata (pre i posle testa toplotnog stresa) uzet uzorak venske krvi. Biohemijski parametri (broj leukocita i trombocita, protrombinsko vreme, antitrombin III, glukoza, amonijak i BUN) mereni su standardnim metodama, kao i sledeći enzimi (AST, ALT, LDH, kreatin-kinaza) i hormoni: FT4, TSH, kortizol, prolaktin, testosteron i insulin. Rezultati. Rezultati istraživanja sistematično su prikazani i dobro dokumentovani sa 23 tabele i 30 grafikona. Pokazano je da: 1) postoji visok stepen homogenosti studijskog uzorka, 2) između ispitivanih grupa nije bilo razlike u vrednostima VO2max, 3) aklimatizacija poboljšava sposobnost organizma da održi termoregulaciju tokom fizičke aktivnosti uz prisustvo toplotnog stresa, 4) ispitanici podvrgnuti aklimatizaciji su imali niže vrednosti srčane frekvence dok vrsta aklimatizacije ne menja značajnije njen efekat na brzinu rada srca; 5) analiza biohemijskih parametara generalno pokazuje da aklimatizacija povoljno deluje na ublažavanje akutnih upalnih procesa i time ograničava posledična mišićna oštećenja, pri čemu izgleda da pasivna aklimatizacija ostvaruje pozitivnije dejstvo, 6) aklimatizacija može biti od značaja za kontrolu koagulacionog statusa tokom toplotnog stresa, 7) aklimatizacija nije imala bitniji uticaj na funkciju ispitivanih endokrinih žlezda tokom toplotnog stresa (osim prolaktina). Zaključak. Aklimatizacija poboljšava sposobnost organizma da održi termoregulaciju tokom fizičke aktivnosti uz prisustvo toplotnog stresa, dok oblik aklimatizacije (pasivna ili aktivna) ne menja bitno efekat izlaganja samoj aklimatizaciji. Analizom biohemijskih parametra generalno možemo zaključiti da aklimatizacija povoljno deluje na ublažavanje akutnih upalnih procesa i time ograničava posledična mišićna oštećenja, pri čemu izgleda da pasivna aklimatizacija ostvaruje pozitivnije dejstvo. Generalno posmatrano pasivni tip aklimatizacije, može biti od značaja za kontrolu pro-/anti koagulacionog statusa koji time može zadobiti veću pažnju u smislu uključenja ove procedure u pripremu vojnika tokom boravka u toplim klimatskim uslovima. Sumarno posmatrano, uticaj aklimatizacije na hormonske pokazatelje ističu njen značaj u odgovoru endokrinog sistema vojnika za obavljanje vojnih aktivnosti u toplim klimatskim uslovima.he aim of this study was to investigate the tolerance to heat stress due to physical exertion in groups of subjects undergoing physical exertion that were previously exposed to passive, or active acclimatization, as well as to determine the effect of acclimatization on physical ability and function of the hormone, enzymatic, and the hemostatic system. Methods. The study involved 40 men, students of the same class of the Military Academy in Belgrade, Department of KOV, aged 19-21 years, divided randomly according to the table of random numbers into 4 groups (K, 0, P and A group). Respondents from K group were subjected to test thermotolerance in comfortable conditions, with submaximal physical load; from 0 group subjected to same test conditions in a warm environment; P group previously exposed to passive 10-day acclimatization; and A group of active acclimatization of the same duration. Investigation of anthropometric and ergometric characteristics included: body height (cm), body weight (kg), nutritional status and body fat composition. Ergometer characteristics (VO2max) were studied indirectly through pulse method by Bruce, with the use of a conveyor belt. Each subject, uderwent venous blood sampling, on two occasions (before and after heat stress test). Biochemical parameters (white blood cell and platelets count, prothrombin time, antithrombin III, glucose , ammonia, and BUN) were measured by standard methods, and the following enzymes (AST, ALT , LDH, creatine kinase), and hormones: FT4, TSH, cortisol, prolactin, testosterone and insulin. Results. The results are systematically presented and well documented within 23 tables and 30 charts. It is shown that: 1) there is a high degree of homogeneity of the study sample, 2) between the groups there were no difference in the values of VO2max, 3) acclimation improves the body's ability to maintain thermoregulation during exercise in the presence of heat stress, 4) subjects underwent acclimatization had lower heart rate, while type of acclimation does not change significantly heart rate; 5) analysis of biochemical parameters in generally shows that beneficial effect of acclimatization on the alleviation of acute inflammatory processes, and thus limiting consequential damage of muscles, where it appears that the passive acclimation achieves more positive effects, 6) acclimatization may be important in control of coagulation during the heat stress, 7) acclimation does not have significant influence on the function of an endocrine glands (except prolactin) during heat stress. Conclusion. Acclimatization improves body's ability to maintain thermoregulation during exercise in the presence of heat stress, while the type of acclimatization (passive or active) does not change significantly the effect of acclimatization itself. By the analysis of biochemical parameters, in general, it can be concluded beneficial effect of acclimatization on the alleviation of acute inflammatory processes, and thus limiting consequential muscle damage, where it appears that passive acclimatization achieved more positive influence. Generally viewed, passive acclimatization may be of importance for the control of pro-/anti coagulation time, which can paid more attention in terms of involvement of these procedures in the preparation of soldiers during warm enviorement. In summary, the effect of acclimatization on hormonal indicators highlight its importance in the response of the endocrine system of soldiers performing military activities in warm climates