Professional athletes as well as the general public are choosing weight training as an effective exercise to reduce body fat and pursue body aesthetics. In order to maximize the effects of weight training, the consumption of various dietary treatments and exercise performance enhancing supplements is increasing. It has been known that regular resistance exercise reduces systolic and diastolic blood pressure, and that nitric oxide is at the center of this mechanism. Adverse reactions to regular exercise occur, and ways to identify and prevent predictors of such unwarranted responses will help form the basis of individualized exercise prescriptions (Bouchard et al., 2012). Nitric oxide acts as an important factor in blood circulation and metabolic control during physical activity, while increasing circulating blood flow to skeletal muscles and heart, increasing the transport of oxygen, substrates, and regulatory hormones, and increasing glucose intake (Brett et al., 1998). It also provides benefits for energy mobilization. Nitric oxide changes carbohydrate metabolism by increasing glucose uptake and inhibiting glyceraldehyde-3-phosphate dehydrogenase, which ultimately changes glycolysis (Mohr et al., 1996).

Interest in arginine as a supplement in resistance exercise is increasing. When the concentration of arginine in the blood increases, glucagon is secreted and the use of glucose increases. At this time, research has shown that reduced glucose is supplied from the liver and glucose utilization in muscles is improved, thereby promoting muscle synthesis (Trabelsi and Lavoie, 1996). Adrenal medulla is known to be activated in response to the acute stress of heavy resistance exercise (Bush et al., 1999). The main functions of arginine are involved in protein synthesis, detoxification of ammonia formed when amino acids decompose nitrogen through the formation of urea, and various biological synthesis activities such as nitric oxide, glutamate, ornithine, and citrulline, and are involved in numerous metabolic pathways (Campbell et al., 2004). In addition to these physiological functions, arginine’s action in the human body increases the concentration of growth hormone and acts antagonistically with insulin, which is involved in energy metabolism, increasing glycogen breakdown and sugar production, which is also known to increase the concentration of triglycerides in the blood (Jobgen et al., 2009).

In a study contrary to the above, it was reported that intravenous L-arginine infusion had no effect on heart rate and blood pressure in healthy people and patients with coronary artery disease (Brett et al., 1998). In particular, L-arginine was administered to skeletal muscles during exercise. There were no changes in skeletal muscle blood flow in the injection study (Hickner et al., 1997). It has been suggested that intravenous L-arginine administered over a short period of time does not affect blood flow in skeletal muscles.

Most of the previous studies related to arginine were conducted on animals or mainly consisted of aerobic exercise as a form of exercise, and most of the studies were conducted on patients with diseases such as obesity, high blood pressure, or diabetes, which included weight training and supplements to improve exercise capacity. It appears that there is a lack of research on arginine intake. In this study, we examined changes in blood pressure and blood variables when consuming 2,000 mg of arginine per day in general adult men using an 8-week resistance exercise program to determine whether arginine can be helpful as a supplement during resistance exercise.

In 1980, Furchgott and Zawadzke discovered that endothelium-derived relaxing factor (EDRF) dilated when exposed to the muscarinic agonist acetylcholine (Arcaro et al., 2002). Under physiological conditions, the endothelium exerts a vasoprotective effect, but endothelial dysfunction is known to contribute to atherosclerotic vascular disease (Lüscher and Noll, 1995). Nitric oxide, called EDRF, is an unstable molecule with a short half-life. Nitric oxide is synthesized within cells from the amino acid L-arginine, molecular oxygen, nicotinamide adenine dinucleotide phosphate hydrogen, and other factors by nitric oxide synthase (NOS), a NOS, and citrulline is produced as a by-product. There are three main types of NOS: inducible NOS, endothelial NOS, and neuronal NOS.

Blood pressure changes depending on cardiac output, blood vessel diameter, and circulating blood flow. During exercise, blood flow resistance increases due to arterial constriction, so the heart increases heart rate to produce more stroke volume, ultimately resulting in an increase in blood pressure. Oral administration of 6 g of L-arginine per day for 3 days improved exercise capacity (Ceremużyński et al., 1997). It is known that the mechanism of blood pressure reduction due to resistance exercise is that the liquid component of the plasma moves into the interstitial area after exercise, resulting in a decrease in plasma volume and thus a decrease in stroke volume (Bush et al., 1999). Reduced stroke volume reduces the preload of the heart and increases the afterload, which reduces cardiac output and thus reduces blood pressure. Nitric oxide has a high diffusion capacity, is easily soluble in lipid layers, and exists in gaseous or dissolved form in the body. Nitric oxide is produced by the main enzyme, L-arginine, and is a substance that relaxes vascular endothelial cells and can suppress the rise in blood pressure. It is known to cause vasodilation and increase exercise performance (Tousoulis et al., 2006). Dietary arginine supplementation may provide a useful treatment option to shift nutrient distribution to promote muscle mass, improve metabolic profile in diet-induced obese rats, and reduce body white fat (Jobgen et al., 2009).

In this study, after taking arginine and performing a resistance exercise program for 8 weeks in men in their 20s, the change in systolic blood pressure showed that the blood pressure of the arginine intake group was 118.20±2.40 mmHg, which was lower than the 120.50±3.28 mmHg of the placebo group, showed a statistically significant decrease. In this experiment, it is believed that a decrease in blood pressure occurred due to the effects of vascular relaxation and improved blood flow due to the intake of arginine. Neutral fat is a major energy source, accounts for approximately 95% of blood lipids, and is known to be a risk factor for coronary artery disease (Durstine et al., 2002). In this study, after consuming arginine and performing a resistance exercise program for 8 weeks in men in their 20s, the change in triglyceride in the arginine intake group was 112.62±2.40 mg/dL, which was statistically significant compared to 119.70±3.28 mg/dL in the placebo group showed a decrease.

As mentioned above, it is believed that arginine intake after 8 weeks of resistance exercise lowered blood pressure and reduced triglyceride, thus functioning as an exercise supplement.