The effect of one week of glutamine supplementation on oxidative stress caused by an intense endurance exercise session

Academic Thesis for Master's Degree

Field: Physical Education and Sports Sciences

Sports Physiology Orientation

Abstract

The purpose of this study was to evaluate the effect of one week of glutamine supplementation on oxidative stress caused by activity.  Nineteen young, healthy, non-smoking men voluntarily participated in this study. Subjects were randomly divided into placebo (10 people) and glutamine (9 people) groups with a control group. Subjects of the glutamine group consumed glutamine solution (0.15 grams per kilogram of body weight + 15 grams of sweetener + 250 ml of water) and the placebo group of the sweetened solution without glutamine (15 grams of sweetener + 250 ml of water) for one week and then ran 14 km at their best.  Subjects drank water as they wished during the activity. Blood was taken from the elbow vein before taking the supplement and 2.5 hours before intense endurance activity, fasting, and immediately and one hour after the activity. The total antioxidant capacity (TAC) increased significantly only in the glutamine group immediately after the activity compared to before (P<0.05). In the glutamine group, reduced glutathione (GHS) showed a significant increase after taking the supplement, immediately and one hour after the activity compared to before taking the supplement, while in the placebo group it was significant only one hour after the activity (P<0.05). The concentration of malondialdehyde (MDA) showed a significant increase only in the placebo group one hour after the activity compared to before (P<0.05). It seems that the consumption of glutamine supplement for 7 days has been able to reduce oxidative stress through the effect on antioxidant elements.

Key words: glutamine, oxidative stress, reduced glutathione.

Chapter

Introduction and introduction Research

1-1. Introduction

Endurance activities increase the heart rate quickly and ultimately cause positive changes in the body and its various functions, including blood circulation and oxygen supply. On the other hand, the issue that sports training leads to tissue damage through free radicals was raised for the first time in 1978, and in the last decade we have witnessed the growth of knowledge about training and oxidative stress. Enzymatic and non-enzymatic antioxidants play a vital role in protecting tissues against oxidative damage during activity. The reduction of each of the antioxidant systems increases the vulnerability of different tissues and cell components against reactive oxygen species (1ROS). Since acute intense endurance training and continuous training increase the consumption of antioxidants, it seems that dietary supplements of antioxidants can be beneficial 51).

It is interesting to note that low and physiological levels of reactive oxygen species are required to generate normal force in skeletal muscle, but high levels of reactive oxygen species cause defective performance in contractility and weakness and fatigue (86).

Research has shown that foods containing antioxidants can prevent cell damage by eliminating free radicals and delay the aging process (14, 64). In this regard, some professional and amateur athletes believe that by taking antioxidants as food supplements, they can improve their sports performance (108).

1-2. Statement of the problem

In recent years, major advances in the field of redox biology have introduced this field as one of the most popular research fields. Although research shows that moderate physical activity and an active life are very effective for the primary and secondary prevention of cardiovascular diseases, type 2 diabetes, metabolic syndrome, and neurodegenerative diseases such as Alzheimer's (60), other researches show that activity Intense physical activity causes oxidative stress (41). Oxidative stress subsequently causes fat peroxidation and damage to proteins and DNA (90).In response to endurance activity, oxygen consumption in the human body systemically increases 10 to 20 times. In muscles, the increase in oxygen consumption is much higher and reaches 100 to 200 times during rest (108). This issue leads to an increase in electron reflux in the mitochondria. Leakage of reactive oxygen species from mitochondria during activity is the main source of oxidative stress (64).

Some researches have shown that intense and exhausting activities cause oxidative stress, inflammatory responses and structural damage in muscle cells, which can lead to an increase in creatine kinase and cytosolic lactate dehydrogenase enzymes in plasma (59). On the other hand, sports activity can affect the production of muscle glutamine and the availability of plasma glutamine differently (5). The change in plasma glutamine concentration during exercise depends on the duration and intensity of exercise (39). It seems that endurance and resistance sports due to intense and long-term energy consumption are associated with an acute decrease in available plasma glutamine (5) because a significant decrease in plasma glutamine concentration has been reported in endurance runners after a marathon race. It is hypothesized that the reduction of glutamine availability after intense training may be due to an increase in glutamine consumption for the cellular energy supply process or gluconeogenesis, which on the other hand is associated with a reduction in glutamine synthesis. Because based on the evidence obtained, glutamine synthesis activity also decreases (29). Also, the consumption of glutamine by active cells of the immune system can also contribute to the depletion of glutamine after intense training (74). In addition, glutamine has a physiological role in cell proliferation, acid and base balance, intercellular transfer of amino acids and synthesis of antioxidants (27,75). Glutamine as a precursor of glutathione can produce glutathione by converting to glutamate. Glutamate, along with cysteine ??and glycine, is one of the three main amino acids that make up glutathione. Glutathione is one of the most important antioxidant substances in the body that can protect the body against oxidative stress (34). From a theoretical point of view, consumption of non-enzymatic antioxidants can reduce oxidative stress caused by intense activity by scavenging free radicals (84). The results of some research show that the use of glutamine supplements in the clinical diet can be used to stabilize high levels of glutathione to prevent damage caused by oxidative stress (65, 99).

Although several studies have been conducted in the field of the effect of the consumption of different antioxidants on the oxidative stress caused by activity (13, 73), but according to the available sources, it seems that so far there is no research showing the effect of the use of the supplement Glutamine as a substance that provides glutathione and as a result its indirect effect on oxidative stress and especially fat peroxidation caused by activity, has not been done and it is not known whether the consumption of glutamine supplement can by increasing the levels of reduced glutathione and as a result the antioxidant capacity of the organism can cause the hunting of free radicals and as a result reduce the oxidative stress caused by activity or not? According to the literature mentioned, the purpose of this study is to determine the effect of one week of consumption Glutamine supplementation on oxidative stress indicators following a session of intense endurance activity.

1-3. The importance and necessity of research

Free radicals are produced in the cell from other biochemical pathways, for example, neutrophils produce superoxide radicals to kill bacteria, viruses, and other genobiotics (18). And procysosomes can produce hydroperoxide radicals in the path of beta oxidation. Due to the high reactivity of unpaired electrons, free radicals can cause extensive damage to various parts of the cell, such as cell membranes, DNA, intracellular proteins, and carbohydrate structures (3). Physical activity creates conditions that are often associated with an increase in the production of active species and free radicals in different tissues (41).