The effect of a period of L-arginine supplementation on the responses of VEGF, endostatin and maximal oxygen consumption of trained wrestlers following an exercise session

Dissertation to receive a master's degree

Exercise Physiology

Persian abstract of the thesis:

Background and purpose: The purpose of this research is to investigate the effect of a period of l-arginine supplementation on the responses of VEGF, endostatin and maximal oxygen consumption of trained wrestlers following a The session was a relaxing activity.

Materials and methods: In this semi-experimental study, 15 trained wrestlers with an average age of 21.13±2.47 years; and body mass index of 24.14±1.71 were selected by voluntary and targeted sampling method, and were randomly assigned to two supplement groups (8 people) and placebo (7 people). In the pre-test and post-test, the subjects continued the Bruce inhibitor protocol until they reached exhaustion, and blood samples were taken from them before and immediately after the protocol. Serum VEGF and endostatin values ??were measured by ELISA method. Also, maximum oxygen consumption and respiratory exchange ratio were measured using a respiratory gas analyzer. Subjects in the supplement group took L-arginine supplement (0.1 g per kg of body weight) for 14 days, and the placebo group received the ineffective supplement. Both groups performed their specialized exercises in the period of supplement consumption according to the previous weeks. Statistical analysis of the data was analyzed using SPSS and Student's t test at a significant level (P?0.05).

Findings: The changes of VEGF, endostatin and also the ratio of VEGF to endostatin of trained wrestlers to a session of resistance training before and after a period of L-arginine supplementation were not statistically significant (P?0.05); The comparison of maximum oxygen consumption and respiratory exchange ratio before and after receiving the supplement was not statistically significant (P?0.05).

Discussion and conclusion: Although our findings were not statistically significant, it seems that the use of l-arginine supplement with a relative increase in VEGF and the ratio of VEGF to endostatin, as well as a decrease in endostatin in the supplemented group in response to activity, caused the relative development of the angiogenesis process. followed by a relative increase in maximum oxygen consumption.

Key words:

VEGF

endostatin

Maximum oxygen consumption

Resistor activity

trained wrestlers

Introduction

The body experiences many biochemical and physiological changes when faced with stress caused by physical activity, which causes various adaptations; Meanwhile, the vascular development of skeletal and cardiac muscles is among the most important adaptations, of which angiogenesis and arteriogenesis are its main processes. Vascular development is influenced by a wide range of physiological and pathological factors, among which the role of physical activity as an important physiological factor is of interest (1). Vascular development caused by activity takes place in response to the greater need of muscles for oxygen and facilitating the exchange process of substances and metabolites to muscle tissue (2). Of course, the acquisition of these adaptations occurs in order to develop the athlete's performance. This is because in an intense activity such as wrestling, where a large amount of muscles are involved, and the time for rest and recovery is very short; Adaptation changes that lead to an increase in the rate of substance exchange in muscles are of great importance. So far, many factors have been identified in justifying this compatibility. Researches consider factors such as the nature and type of activity as well as the energy system involved in the activity, which cause different hormonal, cytokine and metabolic responses, to be effective in the process of vascular development caused by the activity. In addition to these recent researches, the role of some environmental factors such as nutrition has also been considered significant in this process.

Nutritional factors are among the factors that affect physiological processes, and their combination and interaction with training variables is of interest to sports physiology researchers. Today, the identification of biological processes and nutritional factors affecting them has led to the creation of various medicines and food supplements.In the meantime, athletes are prominent as one of the major consumer groups of these supplements; Therefore, sufficient knowledge and understanding about the correct use of these supplements can improve the quality of athletes' performance while improving the level of health. The degree of vascular development of a tissue plays an essential role in providing the physiological needs, establishing the metabolic and homeostatic balances of the tissue, for this reason, the quality of tissue function is considered dependent on it. The main processes of vascular development in adults are angiogenesis [1] and arteriogenesis [2] (6). Angiogenesis is the process of creating new capillaries from existing vessels (4); Arteriogenesis is also an increase in the thickness and diameter of blood vessels (5), and the factors affecting it have many similarities with angiogenesis (6). Angiogenesis is a rare phenomenon in normal and healthy adults, which only occurs locally and temporarily under conditions such as: wound healing, inflammation, and women's sexual cycle (7, 8). However, a wide range of pathological factors such as: diabetes and cancer (4, 9) or in certain physiological conditions such as physical activity (10) affect this process. Nowadays, the study of the factors affecting vascular development has attracted the attention of scientists with a dual approach; On the other hand, stopping this process is effective in cancer treatment (11);  And on the other hand, the development of this process is of interest in the treatment of vascular congestion and improving the performance of athletes (12).

According to research, physical activity is one of the important factors of vascular development (10, 13). At rest, about 20% of cardiac output is allocated to skeletal muscles, while during muscle activity, this value increases 10-20 times. Based on this, as a result of continuous activity, the vascular structure of the skeletal and cardiac muscles changes in order to adapt to the stresses caused by the activity and to meet the needs of the active muscles (14). The extent of these changes is different according to the type and intensity of stress caused by the activity (2). It is for this reason that in high-pressure sports such as wrestling, which puts a lot of pressure on the body's metabolic and homeostatic systems, the role of the vascular system is significant (15). The need for quick adaptation in order to cope with the severe changes of the acid-base system of the blood plasma and also the need for energy during a race reaches the maximum possible. On the other hand, more dependence on anaerobic systems during the competition and the accumulation of metabolites can lead to metabolic acidosis and a severe drop in athlete performance. Also, the role of the aerobic system in meeting the needs of the athlete's recovery period is very significant. Vascular development by expanding the range of muscle tissue exchanges can affect the quality of the athlete's performance, therefore it is important to know the factors that control this process(16, 17).

Generally, the process of vascular development is under the control of several angiogenic (stimulators) and angiostatic (inhibitors) factors(18). So far, more than a dozen metabolic factors affecting this process have been identified, among which vascular endothelial growth factor[3] is known as the most important stimulus, and endostatin[4] is known as the most important inhibitory factor of vascular development

Vascular endothelial growth factor is a 45 kilodalton glycoprotein, which is secreted from endothelial cells and is the most important factor in most researches. Angiogenesis is known (4, 20). This glycoprotein sends messages through binding to VEGFR-1 and VEGFR-2 receptors of endothelial cells (21). By stimulating this glycoprotein, cascade chains of reactions are activated, which respectively cause the survival, proliferation, migration and permeability of endothelial cells and finally complete the process of angiogenesis by sprouting or dividing into two halves (22, 23). This 20 kDa peptide, which originates from type 18 collagen, reduces the angiogenesis process by reducing the proliferation and increasing the apoptosis of endothelial cells and activating other angiostatic factors (4, 25).