Abstract. The need to increase sport achievements in the setting of ever-increasing competition and approximation of the functional capabilities of the human body to the border of reserve mechanisms make us seek new ways to stimulate physical performance and psycho-emotional stability of athletes. One of the most promising areas for improving the results of training and competitive activities of athletes is the use of pharmacological agents which are not prohibited by WADA. At the present time the substances that are on L-arginine based, in the form of food supplements firmly took their place in the pharmacological support of children’s and youth sport and high performance sport.

Materials and Methods. Studies of the safety and efficacy of Tivortin aspartate (L-arginine aspartate) were conducted in skilled male athletes aged 18 to 26, represented the different groups of sports – cyclic (track and field athletics, middle distance running) and endurance (weightlifting) ones. The study involved 69 healthy skilled (first-rate and sub-master sportsmen) athletes who were on a special preparatory stage of the preparatory period of the annual macrocycle in the standard training mode. All study participants had no manifestations of any acute respiratory viral infections and the history of diseases of cardio-respiratory, endocrine, digestive, excretory systems with clinical manifestations. The athletes signed Informed Consent, in which they confirmed their voluntary consent to participate in the study after acquaintance with all its features that could affect their free decision. The study was randomized, blind and placebo-controlled. Randomization of the athletes within both groups (Group 1 – 36 track and field athletes, Group 2 – 33 weightlifters) was conducted before the signing the Informed Consent. By simple randomization within the groups, 4 subgroups of athletes (2 main and 2 control) were formed; they did not have statistically significant differences in the initial clinic and anamnestic, anthropologic and demographic, pedagogical, qualification and gender characteristics. Treatment groups included 46 athletes, of them 24 middle distance runners and 22 weightlifters, and 23 athletes as controls (12 runners and 11 weightlifters). Tivortin aspartate as a 20 % oral solution at a daily dose of 40 ml, divided into two 20 ml administrations, was used immediately after meals for 21 study days. Before and after the study, all athletes underwent complete physical examination by a specialist in sports medicine, including an assessment of the functional state of the cardio-respiratory system; laboratory diagnostics, psychophysiological testing with the calculation of the stress factor and evaluation of the incidence of side effects and subjective complaints in the athletes during the drug administration were conducted as well. Laboratory parameters included standard measures of hematological (white blood cell, platelet and red blood cell counts, hemoglobin content, hematocrit, mean absolute and average hemoglobin concentration in red blood cells, mean volume and anisocytosis of red blood cells) and biochemical homeostasis (total protein, bilirubin, urea, creatinine, glucose, cholesterol and triglycerides, potassium, sodium, ionized calcium, magnesium and phosphorus; activity of alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl transaminase, α-amylase, alkaline phosphatase; serum iron content, total iron binding capacity of serum and transferrin saturation; activated partial thromboplastin time). Moreover, prooxidant-antioxidant balance (PAB) in the erythrocyte membranes was studied based on the malonic dialdehyde/reduced glutathione ratio. The special pedagogical performance measures were also studied: for runners – PWC170 and running time for simulated competitive distances of 800 m and 1500 m, for weightlifters – the height of the bar lift in jumping and snatching and the timing of these exercises.

Results. The data obtained clearly indicate the absence of subjective complaints, objective significant shifts in standard laboratory parameters and the functional state of athletes under the influence of the course of taking Tivortin aspartate, which suggests its high safety profile. In this case, the drug has a positive effect on the PAB with a decrease in malonic dialdehyde content in the erythrocyte membranes from 3.380±0.281 to 2.962±0.038 nmol/10^-6 per erythrocyte (p <0.05), and an increase in reduced glutathione content by 16.3% in the controls. Similar figures in weightlifters are 3.345±0.082 vs. 3.144±0.076 nmol/10^-6 for erythrocyte (p <0.05) and 25.5% as compared to controls. Under the influence of Tivortin aspartate, the severity of psychophysiological stress also significantly decreases by 9.5 points, while this measure in the controls increases by 3.59 points (p <0.05) in track and field athletes and changes to 4.52 and 2.86 points, respectively, in weightlifters. At the same time, there is a significant increase in performance measures of athletes: PWC170 in runners increases by 21.8 % vs. controls, in which this measure increases by only 9.62 % at the end of the study; and the time for passing the competitive distances of 800 m and 1500 m is reduced by 3.74 and 4.14 sec, respectively, versus the values of the runners of the control group (p <0.05). Similarly, the performance measures of weightlifters are changed.

Conclusions. We believe that the rise in the performance of runners in the course of administration of Tivortin aspartate is primarily achieved by increasing the oxygen transport function of the blood by reducing its viscosity and improving the structural and functional state of erythrocytes. In weightlifters, the observed increase in performance is caused mainly by increasing the height of the bar lift and reducing the time of exercise and by the optimization of intermuscular and neuromuscular interaction during the normalization of lipid peroxidation processes in the membranes of nerve cells under the influence of L-arginine.

Keywords: sport, work capacity, ergogenic medical drugs, L-arginine, Tivortin aspartate, oxidative homeostasis, psychophysiological stress.