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Introduction. Energy drinks (EDs) are widely used by athletes as ergogenic agents. The aims of this study were to determine the acute, chronic and direct effects of Red Bull®, one of the most consumed EDs, on cardiodynamics and the parameters of oxidative stress in physically active and physically inactive rats. Material and method. The study lasted 4 weeks. Rats were divided into 2 groups depending on the consumption of Red Bull (3.75 ml/kg), and each group was divided into 2 subgroups, depending on the physical activity. The trained rats were subjected to a swimming practice (1h per day, 5 days a week). After sacrificing, the animals were sampled for venous blood to determine the plasma redox status. Subsequently, the hearts were isolated and perfused by Langendorf method of retrograde perfusion. The coronary flow and parameters of left ventricular function were monitored: maximum rate of change of left ventricle pressure, minimum rate of change of left ventricle pressure, systolic left ventricular pressure, diastolic left ventricular pressure, and heart rate. The biomarkers of oxidative stress in the blood and effluent were determined by the spectrophotometric methods: superoxide anion radical, hydrogen peroxide, index of lipid peroxidation, nitrite monoxide in the form of nitrite, as well as the parameters of antioxidant protection system: superoxide dismutase, catalase and reduced glutathione.Results. The negative effects of the acute, chronic and direct administration of the ED on cardiac function were registered in untrained animals. In trained animals, the acute and chronic consumption of the ED resulted in increasing the coronary flow and most cardiodynamic parameters, while the direct administration of the ED resulted in decreasing rates of contractility and relaxation, and was associated with the depression of cardiac function. In untrained animals, the administration of the ED had a pro-oxidative effect in the coronary effluent (acute and direct administration) as well as in blood (acute and chronic administration). In trained animals, the acute, chronic and direct administration of the ED had a pro-oxidative potential in the coronary effluent, whereas antioxidant activity was registered in the blood after the acute administration of the ED. Conclusion. Our study contributes to the knowledge on the effects of EDs on cardiodynamics and the redox status correlated with the exercise status.

Cilj istraživanja bio je da analizira promene parametara redoks statusa i inflamacije kod pacova izloženih eksperimentalnom modelu pretreniranosti. Pacovi su podeljeni u tri grupe (kontrole, umereno trenirani, preterano često trenirani pacovi) i podvrgnuti različitom trenažnom protokolu tokom 9-12 nedelja. U krvi pacova izmereni su nivoi markera oksidacionog stresa (superoksid anjon radikal, vodonik peroksid, nitriti, lipidni peroksidi), antioksidativne zaštite (aktivnost superoksid dismutaze i katalaze, nivo redukovanog glutationa) i citokina (interleukina 6 i tumor nekrozis faktora alfa). Primenjeni eksperimentalni protokol plivanja nije indukovao pretreniranost kod pacova. Primenjeni protokoli treninga nisu doveli do poremećaja redoks ravnoteže u krvi pacova, već do smanjenja nivoa prooksidativnih parametara u plazmi (kod umereno treniranih pacova) odnosno ushodnu regulaciju antioksidativnog sistema (kod preterano često treniranih pacova). Primenjeni protokoli treninga nisu doveli do značajnih promena nivoa proinflamatornih medijatora u plazmi pacova. Obzirom na izostanak dijagnoze pretreniranosti, naša studija ne doprinosi značajno rasvetljavanju uloge oksidativnog stresa i inflamacije u ovom sindromu, međutim, ona daje važne smernice za dizajniranje budućih plivačkih trenažnih protokola, posebno onih koji za cilj imaju indukovanje pretreniranosti. Takođe, naša studija doprinosi saznanjima o efektima različitih trenažnih protokola na redoks i inflamatorni status vežbača. The aim of the research was to analyze the changes of parameters of redox state and inflammation in blood of rats subjected to an experimental model of overtraining. The rats were divided into three groups (control, moderately trained, overfrequently trained rats) and subjected to different training protocol during 9-12 weeks. In rats’ blood following markers were measured: oxidative stress markers (superoxide anion radical, hydrogen peroxide, nitric oxide, index of lipid peroxidation), markers of antioxidative defence (superoxide dismutase and catalase activity and level of reduced glutathione) and markers of inflammation (interleukin 6 and tumor necrosis factor alpha). Applied experimental protocol did not induce overtraining in rats. Applied training protocols did not induce disturnabnce of redox state in blood, but on the contrary: the decrease of levels of prooxidative parameters (in moderately trained rats) and upregulation of antioxidative defence (in overfrequently trained rats). Applied training protocols did not induce significant changes in levels of proinflammatory mediators in rats’ blood. Given the lack of diagnosis of overtraining, our study does not contribute significantly to shed light on the role of oxidative stress and inflammation in this syndrome, however, it provides important guidance for designing future swimming training protocols, especially those that aim to induce overtraining. Also, our study contributes to knowledge about the effects of different protocols of training on redox and inflammatory status of exercisers.

Cilj istraživanja bio je da ispita efekte protokola usmerenog izazivanju pretreniranosti na kardiodinamiku, koronarni protok i oksidativni stres u koronarnom efluentu izolovanog srca pacova. Pacovi su podeljeni u tri grupe (kontrole, umereno trenirani, preterano često trenirani pacovi) i podvrgnuti različitom trenažnom protokolu tokom 9-12 nedelja. Nakon žrtvovanja životinja, srce je izolovano i perfundovano na Langendorf aparatu, a tokom koronarne autoregulacije (koronarni perfuzioni pritisak 40-120 mmHg) praćeni su sledeći kardiodinamski parametri leve komore: maksimalna i minimalna stopa promene pritiska, sistolni i dijastolni pritisak, srčana frekvenca. Koronarni protok meren je floumetrijski, a u koronarnom efluentu određeni su nivoi parametara oksidacionog stresa (superoksid anjon radikal, vodonik peroksid, nitriti, lipidni peroksidi). Primenjeni eksperimentalni protokol plivanja nije indukovao pretreniranost kod pacova. Preterano često plivanje dovelo je do pozitivnih promena u kardiodinamici i koronarnom protoku izolovanih srca pacova, u većoj meri od umerenog trenažnog protokola. Rezultati naše studije potvrđuju pozitivne efekte redovnog aerobnog treninga na srce, i pokazuju da često vežbanje, ukoliko je intenzitet vežbanja umeren, nema štetne efekte na kardiodinamiku. U poređenju sa kontrolama, srca umereno treniranih, a posebno često treniranih pacova, produkovala su niže nivoe prooksidanata. Ovakvi rezultati verovatno su posledica bolje srčane funkcije, kao i aktivnosti antioksidativnog sistema kod često treniranih pacova. Obzirom na izostanak dijagnoze pretreniranosti, naša studija ne doprinosi značajno rasvetljavanju veze između ovog fenomena, funkcije srca i uloge oksidativnog stresa u ovom sindromu, međutim, ona daje važne smernice za dizajniranje budućih plivačkih trenažnih protokola, posebno onih koji za cilj imaju indukovanje pretreniranosti. Takođe, naša studija doprinosi saznanjima o efektima različitih trenažnih protokola na kardiodinamiku i redoks status u srcu. The aim of the research was to explore the effects of the training protocol designed for overtraining induction on cardiodynamics, coronary flow and oxidative stress in coronary effluent from an isolated rat heart. The rats were divided into three groups (control, moderately trained, overfrequently trained rats) and subjected to different training protocol during 9-12 weeks. After sacrificing animals, hearts were excised, isolated and perfused on a Langendorf apparatus, and following cardiodynamic parameters of the left ventricle were measured during coronary autoregulation (coronary perfusion pressure 40-120 mmHg): maximal and minimal rate of pressure change, systolic and diastolic pressure, heart rate. Coronary flow was measured flowmetrically, and in coronary effluent following parameters of oxidative stress were measured: superoxide anion radical, hydrogen peroxide, nitric oxide, lipid peroxides. Applied experimental protocol did not induce overtraining in rats. Overfrequent swimming lead to positive changes in cardiodynamics and coronary flow, in a greater rate than moderate training. The results of our study confirm positive effects of regular aerobic exercise training on the heart, and show that frequent exercise, if the intensity of exercise is moderate, it is not harmful for the heart. In comparison with controls, hearts of rats trained moderately, and especially hearts of overfrequently trained rats, produced lower levels of prooxidants. Those results are probably a consequence of better cardiac function, as well as activity of antioxidative system in overfrequently trained rats. Given the lack of diagnosis of overtraining, our study does not contribute significantly to shed light on the relationship between this phenomenon, function of the heart and the role of oxidative stress in this syndrome, however, it provides important guidance for designing future swimming training protocols, especially those that aim to induce overtraining. Also, our study contributes to knowledge about the effects of different protocols of training on cardiodynamics and redox status of the heart.