Compact food bar improves cardiopulmonary function in men military athletes: A randomized, placebo-controlled, single-blind clinical trial
Saeid Hadi1, Reza Amani2, Mostafa Mazaheri Tehrani3, Vahid Hadi4, Sudiyeh Hejri5, Sayid Mahdi Mirghazanfari6, Gholamreza Askari7
1 Department of Community Nutrition, School of Nutrition and Food Sciences, Isfahan University of Medical Sciences, Isfahan; Department of Health, Science and Research Branch, AJA University of Medical Sciences, Tehran, Iran
2 Department of Community Nutrition, School of Nutrition and Food Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
3 Department of Food Science and Technology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
4 Department of Health, Science and Research Branch, AJA University of Medical Sciences, Tehran, Iran
5 Department of Nutrition, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
6 Department of Physiology and Iranian Medicine, School of Medicine, AJA University of Medical Sciences, Tehran, Iran
7 Department of Community Nutrition, School of Nutrition and Food Sciences; Food Security Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
|Date of Submission||23-May-2020|
|Date of Decision||02-Feb-2022|
|Date of Acceptance||09-Mar-2022|
|Date of Web Publication||27-Aug-2022|
Dr. Gholamreza Askari
Department of Community Nutrition, School of Nutrition and Food Sciences, Isfahan University of Medical Sciences, Isfahan
Source of Support: None, Conflict of Interest: None
Background: This study aimed to evaluate the effects of compact food bar (CFB) designed on cardiopulmonary function in men athletes who serve in military service. Materials and Methods: In this randomized, single-blind, controlled clinical trial, 46 men of military staff were arranged into 2 groups and studied for 28 days; one branch used 3 packs daily, 700 kcal each, of CFB with Functional compounds (Caffeine and L-arginine) and the other group used regular food during training course. Maximal oxygen uptake (VO2 Max) in vitro with cardiopulmonary exercise test, body composition, and physical activity were assessed and recorded at baseline and end of the study period. Results: VO2 Max (P = 0.05) significantly increased in CFB group compared with baseline. Moreover, VO2 Max (P = 0.01), VO2/HR (P = 0.04), oxygen uptake/heart rate (VO2/HR) (P = 0.03), and ventilation per minute/oxygen uptake (VE/VO2) (P = 0.03) significantly increased in CFB group compared with control group. In comparison, there was no significant difference in mean ventilation per minute/carbon dioxide production (VE/VCO2) (P = 0.41), ventilation per minute (VE) (P = 0.69), and breathing frequency (P = 0.056). No significant effect of CFB was found on weight, body mass index (P = 0.23), lean body mass (P = 0.91), and body fat mass (P = 0.91). Conclusion: Our results show that intervention with CFB is more effective than regular diet in improving cardiopulmonary function in men athletes who serve in military service.
Keywords: Athlete, cardiorespiratory function, compact food bar
|How to cite this article:|
Hadi S, Amani R, Mazaheri Tehrani M, Hadi V, Hejri S, Mirghazanfari SM, Askari G. Compact food bar improves cardiopulmonary function in men military athletes: A randomized, placebo-controlled, single-blind clinical trial. J Res Med Sci 2022;27:60
|How to cite this URL:|
Hadi S, Amani R, Mazaheri Tehrani M, Hadi V, Hejri S, Mirghazanfari SM, Askari G. Compact food bar improves cardiopulmonary function in men military athletes: A randomized, placebo-controlled, single-blind clinical trial. J Res Med Sci [serial online] 2022 [cited 2023 Jun 1];27:60. Available from: https://www.jmsjournal.net/text.asp?2022/27/1/60/354866
| Introduction|| |
Physical fitness, as a necessity for any athlete, includes physical health, the ability to perform exercises continuously and skillfully, the ability to return to normal after high pressure, and confidence in dealing with any situation for a military person.
Proper nutrition is one of the most important aspects of health and plays a decisive role in the level of physical fitness and mental performance of individuals, especially military personnel. The physical needs of the individuals during times of crisis and military operations, which are accompanied by stress or short or long-term pressures, are completely different from normal living conditions. Also, these psychological and physical stresses, which are different and more complex, determine nutritional needs when combined with harsh environmental conditions. It has now become clear that proper selection of carbohydrates, proteins, and fluids, as well as their intake timing, may affect athletic performance.
In addition to the effect of the type and level of macronutrients and fluids, functional compounds such as caffeine, vitamins and minerals, probiotics, beta-alanine, arginine, and creatine could also affect performance., Functional foods contain special compounds that have not only nutritional and energy-providing features but also have well-established and proven health-promoting, preventive, and disease-reducing properties.,, Clinical studies have highlighted that the use of beta-alanine supplements for at least 4 weeks increases athletic performance and reduces the time it takes to reach maximal oxygen uptake (VO2 Max) fatigue.,,
In critical situations, food choices are limited, and the comparative diets available replace compact food bar (CFB) during missions. CFB is part of the diet that is used in times of crisis, maneuvers, and military missions., These foods are durable and ready to eat. Also, they have low volume and weight, which is significant regarding that a soldier can carry his or her diet easily., In addition to athletes and military personnel, CFB can be used in times of crisis and treatment for humanitarian purposes. One of the criteria for evaluating physical fitness performance is cardiac and pulmonary endurance, which can be measured by the cardiopulmonary exercise test (CPET). CPET predicts the ability of cardiac and pulmonary function by measuring the parameters of VO2 Max, carbon dioxide production (VCO2), ventilation per minute (VE), ventilation per minute/oxygen uptake (VE/VO2), ventilation per minute/carbon dioxide production (VE/VCO2), and oxygen uptake/heart rate (VO2/HR).
The efficiency of the ventilation and oxygen transmission system is of great importance in improving cardiac and pulmonary readiness. It has been reported that some supernatural food compounds increase VO2 Max, but not the amount of oxygen delivered to the tissue per minute.,,, VO2 Max is one of the indicators that is highly correlated with aerobic performance. Increased cardiac and pulmonary endurance could lead to an increase in the amount of VCO2 and increased VE. Increased lactic acid stimulates the respiratory center and increases VE, leading to an increase in the VE/VO2 ratio, indicating the onset of the anaerobic phase. The ratio of ventilated air volume to the amount of VE/VCO2 also shows the efficiency of the respiratory system. Moreover, the decrease in this ratio indicates an increase in cardiac and pulmonary efficiency in energy generation from the aerobic pathway and delayed anaerobic stage.
Despite several works on the effect of functional food on improving performance and physical fitness,,,, few studies have examined a CFB with functional food such as caffeine and L-arginine to evaluate cardiac and pulmonary endurance. This study aimed to investigate the effect of consuming CFB on the cardiac and pulmonary endurance of the military personnel compared to the control group.
| Materials and Methods|| |
Participants and eligibility screening
Participants were recruited from military athletes of the Tehran military army in January 2020. Criteria for entering the study included age range of 20–45 years, no use of antioxidant and herbal supplements since at least 1-month before the start of the study, no history of any allergies to certain compounds, and no use of tobacco. Also, the participants with known metabolic disorders including coronary heart disease, diabetes mellitus, hyper- or hypothyroidism, renal disease, liver disorders, inflammatory diseases, taking antioxidant, anti-inflammatory, or multivitamin supplements within the past 12 weeks, therapy with medications, adherence to a special diet or weight loss program last 12 weeks were excluded.
This study was designed as a randomized, single-blind, placebo-controlled clinical trial with two parallel groups over a 28-day period. Participants took part in this study after learning about the objectives and methods of conducting the study, and their willingness to cooperate was confirmed by them signing the written consent form. This study was approved by the ethics committee of the Isfahan University of Medical Sciences, Isfahan, Iran. This clinical trial is currently registered on the Clinical Trials Registration, coded as IRCTID: IRCT20121216011763N43.
A total of 90 athletes were evaluated for inclusion criteria; 54 of them met participation eligibility of the study and 8 refused to participate in the study. The remaining 46 participants were assigned to two groups randomly: an intervention group (23 participants) receiving a CFB with functional food and a control group (23 participants) receiving a regular food used in military training courses intervention for 28 days. A simple randomization method was used to assign the participants in two groups in accordance with computers-generated unique codes [Figure 1]. Since our study is a pilot study, we did not find similar studies. Therefore, for calculation of sample size, we used the following formula, where standard deviation, β (type two error), and confidence interval were 0/18, 0/05, and 95%, respectively. We needed 23 participants for each group.
M = (ZS/D) 2
Each athlete received a diet (~2800–3200 kcal) according to RMR and based on the Mifflin-St Jeor equation. This diet was adjusted for their physical activity. The macronutrient composition of the diet was approximately 50%–55% carbohydrates, 20% protein, and 30% fat. However, the nutritionist designed the requirement of energy and distribution of macronutrients and provided special dietary recommendations based on AHA guidelines.
The intervention group received 3 CFBs each day (with every CFB being 125 g and 700 kcal) for 10 days. Three CFBs provided 2100 kcal energy needed daily, and the rest of the energy requirement was supplied from foods including bread, cheese, nuts, and dried fruit o provide the required daily energy daily. The control group received a regular diet (the same calories as the intervention group) that was cooked in a military kitchen. The conditions for performing the activities in terms of some variables such as temperature, humidity, sports coverage, sleep, type of sports, and caloric activities were the same for all samples. Test measurements were performed for all participants from 7:15 to 9 o'clock.
Diet formulation features
In this study, to produce CFBs, several ingredients were used: corn and whole-grain soybean flour purchased from Ilia Factories, Kermanshah, Iran, and Toos Soyan, Mashhad, Iran, respectively; milk protein concentrate (MPC) (Golshad, Mashhad, Iran) to supply protein; cocoa butter substitute (Cargill, Kuala Lumpur, Malaysia) as a source of lipid' granule form of (Iran sugar Co., Tehran, Iran) as a source of simple sugars; lecithin (amphiphilic ingredient thus great emulsifier) and polyglycerol polyricinoleate (provided from Nestlé Iran, Co., Tehran, Iran); cocoa powder (Delfi Cocoa, Johor Darul Takzim, Malaysia); and formulated vitamins and minerals blend (Osve Iran Pharm, Inc. Tehran, Iran) to meet the IOM requirements for EFPs [Table 1]. The CFBs output data for carbohydrate, fat, and protein are shown in [Table 2].
|Table 1: Energy values, amounts of macronutrients, micronutrients, and functional compounds used in the military diet based on the recommended dietary allowance|
Click here to view
|Table 2: Values and shares of energy from macronutrients in 100 g of the military diet|
Click here to view
This study aims to investigate the effect of consuming CFB with functional compounds (caffeine and L-arginine) on the cardiac and pulmonary endurance of the military personnel compared to the control group. Energy-consuming exercises were designed for volunteers who needed to be fed by appropriate ratios of macronutrients such as carbohydrates, fats, and proteins. However, the type of macronutrients was taken into account precisely to promote physical performance outcomes. For example, casein and arginine were used as the protein and amino acid for MPC and soybean, respectively. Multivitamins, minerals, L-arginine (1 gr/2100 kcal), and caffeine (500 mg/2100 kcal), in addition to the CFBs, guaranteed adequate energy supply, enhanced immune system, reduced oxidative stress, and finally increased functional capacity.
In this study, cardio-respiratory endurance was evaluated using the laboratory method by the respiratory gas analyzer (ergospirometry or CPET). For this purpose, a MetaLyzer 3B model by the German Cortex Biophysik Co. was utilized to directly evaluate maximum oxygen consumption (ml/kg/min), VCO2, VE, VE/VO2, VE/VCO2, and VO2/HR. The measurement of anthropometric indicators was performed by the Bioelectrical Impedance Analysis device (In Body S10 model, made in South Korea).
The normalization and the distribution of the data were evaluated using the Kolmogorov–Smirnov test. The independent t-test was used to calculate intergroup changes. The paired t-test was used to evaluate intragroup changes before and after the intervention. Each of the variables was reported as a mean ± standard deviation. Analysis of covariance was used to compare the mean values of the tests between the two groups at the end of the study after modifying the distortion variables, including age and height. P < 0.05 was considered significant in all tests. All data were analyzed using the SPSS software version 20 (IBM SPSS Statistics, Armonk, USA).
| Results|| |
The results of the Kolmogorov–Smirnov test revealed the normal distribution of data in the intervention and control groups. There is no statistically significant difference between the two groups in terms of baseline characteristics including age, body mass index (BMI), height, weight, level of physical activity, and energy and protein intake (P > 0/05) [Table 3]. As it is shown in [Table 4], changes in weight, BMI, body fat percentage, and fat mass were not significant in each group and between group at the end of study (P > 0.05).
|Table 3: General characteristics of individuals at the beginning of the study|
Click here to view
|Table 4: Anthropometric indicators and physical activity at the beginning and end of the study in the intervention and control group|
Click here to view
As shown in [Figure 2], there was statistically significant in VO2 Max, VE/VO2, and VO2/HR in the CFB group pared with the control group during the 28-day intervention period (P < 0.05). Meanwhile, there was no significant difference observed in the average VE/VCO2, VE, and breathing frequency (BF) (P > 0.05) [Table 5].
|Figure 2: Mean ± standard deviation of VO2 Max, VO2/HR and VE/VO2 at baseline and day 28 in compact food bar and control groups|
Click here to view
|Table 5: Indicators of cardiac and pulmonary endurance at the beginning and end of the study in the intervention and control groups|
Click here to view
| Discussion|| |
To the best of our knowledge, this study is the first randomized, double-blind placebo-controlled clinical trial designed to assess the effect of CFB on cardiopulmonary endurance in military athletes. One of the major findings of the present paper is that consuming a CFB improved the increase in cardiorespiratory endurance based on the measurement of VO2 Max, VE/VO2, and VO2/HR in the intervention group compared to the control group. Meanwhile, there was no significant difference in the average weight, BMI, body fat mass body fat mass (BFM), and lean body mass (LBM) in the intervention group compared to the control group before and after the study.
The results of this study, consistent with those of Entezari et al., showed an increase in VO2 Max in the intervention group compared to the control group at the end of the study. One study indicated that the 5 mg/kg dosage of caffeine increased the strength and speed of exercise. Another study found that caffeine consumption on a bicycle test increased the exhaustion time and VO2 Max. Another study demonstrated that caffeine consumption at a dose of 5 mg/kg increased athletic performance and VO2 Max. In a study by Steven et al., the use of arginine amino acids enabled the improvement of muscle mass and performance during exercise. In one study, 2 g/day of L-arginine supplementation in men for 15 days reduced fatigue and increased VO2 Max. In another study, L-arginine for 42 days at a dose of 2 g/day improved athletic performance in male athletes,, which was in line with our study.
In the present study, the daily intake of CFB significantly improved the ratio of VE/VO2. In several studies, the ratio of VE/VO2 has been measured as one of the indicators of respiratory efficiency., Also, the mean changes in the VE/VO2 ratio decreased after 28 days of intervention in the functional diet compared to the control group, i.e., the intervention improved lung function, while no significant difference was observed in VE/VCO2. The difference in research results between VE/VCO2 and VE/VO2 ratios can be explained by the fact that VE/VCO2 has less variability than VE/VO2.
The findings of this study on VE/VCO2 are inconsistent with the results of Farrell et al., probably due to the incremental test type used in cardio and pulmonary testing. The results of our intervention revealed that 28 days of supplementation with CFB improved the VO2/HR ratio. In this regard, the higher the amount of oxygen in the body between two consecutive heartbeats is, the more effective the cardio-respiratory system will be in delivering oxygen to the active muscles. According to the present study, the intervention has a significant effect on this ratio. These findings are consistent with the results of research by Habedank et al.
It seems that CFB with functional food such as arginine, multivitamins-minerals, and caffeine could be effective in boosting athletic power by increasing the delivery of oxygen to the active muscles and subsequently increasing the oxygen uptake in the active muscles., The role of arginine in nitric oxide endothelial synthesis could be regarded among the possible mechanisms of the functional compounds used in the military diet to improve and increase oxygen delivery capacity. This capacity, in turn, is a measure of improving aerobic capacity, cardiorespiratory endurance, and functional capacity. Nitric oxide is a vasodilator that increases blood flow to tissues during exercise, leading to increased oxygen delivery and oxygen uptake into the active muscles. Therefore, improving the aerobic capacity of skeletal muscles enhances the oxidative capacity of skeletal muscle and produces more ATP in the Krebs cycle path by improving peripheral blood flow and muscular aerobic energy and using fatty acids as a sustainable energy source.
Caffeine might be responsible for other possible mechanisms of the effect of a compact diet. Caffeine increases energy consumption, stimulates the release of fatty acids from adipose tissue,, boosts and regenerates energy sources faster, delays the fatigue threshold (possibly by preventing acid-base imbalance and reducing glycolysis and lactic acid accumulation in the muscles), and subsequently reduces the VE/VO2 ratio. Caffeine is a potentiating factor affecting the release of catecholamines and also cell protection against cell damage due to its antioxidant effects. Caffeine can improve endurance and physical function in long-term activities with submaximal intensity. Moreover, it can be effective in prolonging the fatigue reaching time by storing glycogen from increased lipolysis and consuming fatty acids as an energy supplier.,
To the best of our knowledge, this study is the first that assessed the effect of consuming CFB on the cardiac and pulmonary endurance of athletes. Despite the advantages of this research, it also suffered from some limitations. First, the sample size was small and participants of the study were restricted to athlete men. Hence, this could limit the generalizability of results. Second, the duration of intervention in this study was short. Therefore, further studies are warranted to confirm these results. Third, we could not evaluate biochemical indices including serum level of ghrelin, leptin, and NPY due to financial constraints and available facilities.
| Conclusion|| |
This study indicated that consuming a nutritional supplement (i.e., CFB) with functional food in military athletes in difficult conditions and intense activity has positive effects on improving cardiac and pulmonary endurance. However, no significant effects were observed on BMI and body composition indices.
All protocols were approved by the Iranian Registry of Clinical Trials (IRCT). Also, all participants gave written informed consent to participate in this study.
The present study was conducted with the financial support of the Vice Research Chancellor of Isfahan University of Medical Sciences. We would like to express our gratitude to all the participants in the study.
Financial support and sponsorship
This study was financially supported by the Department of Community Nutrition, School of Nutrition and Food Sciences, Isfahan University of Medical Sciences, Isfahan, Iran.
Conflicts of interest
There are no conflicts of interest
| References|| |
McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy, and Human Performance. Lippincott Williams & Wilkins; 2010.
Farajzadeh D, Golmakani M. Formulation and experimental production of energy bar and evaluating its shelf-life and qualitative properties. J Mil Med 2011;13:181-7.
Jaeger SR, Cardello AV. A construct analysis of meal convenience applied to military foods. Appetite 2007;49:231-9.
Deldicque L, Francaux M. Functional food for exercise performance: Fact or foe? Curr Opin Clin Nutr Metab Care 2008;11:774-81.
Shay LE, Seibert D, Watts D, Sbrocco T, Pagliara C. Adherence and weight loss outcomes associated with food-exercise diary preference in a military weight management program. Eat Behav 2009;10:220-7.
Harty PS, Cottet ML, Malloy JK, Kerksick CM. Nutritional and supplementation strategies to prevent and attenuate exercise-induced muscle damage: A brief review. Sports Med Open 2019;5:1.
Yari Z, Cheraghpour M, Alavian SM, Hedayati M, Eini-Zinab H, Hekmatdoost A. The efficacy of flaxseed and hesperidin on non-alcoholic fatty liver disease: An open-labeled randomized controlled trial. Eur J Clin Nutr 2021;75:99-111.
Yari Z, Cheraghpour M, Hekmatdoost A. Flaxseed and/or hesperidin supplementation in metabolic syndrome: An open-labeled randomized controlled trial. Eur J Nutr 2020;60:287-98.
Ghiasvand R, Askari G, Malekzadeh J, Hajishafiee M, Daneshvar P, Akbari F, et al.
Effects of six weeks of β-alanine administration on VO2 max, time to exhaustion and lactate concentrations in physical education students. Int J Prev Med 2012;3:559.
Gross M, Bieri K, Hoppeler H, Norman B, Vogt M. Beta-alanine supplementation improves jumping power and affects severe-intensity performance in professional alpine skiers. Int J Sport Nutr Exerc Metab 2014;24:665-73.
Furst T, Massaro A, Miller C, Williams BT, LaMacchia ZM, Horvath PJ. β-Alanine supplementation increased physical performance and improved executive function following endurance exercise in middle aged individuals. J Int Soc Sports Nutr 2018;15:32.
Barrett AH, Cardello AV. Military Food Engineering and Ration Technology. DEStech Publications, Inc.; 2012.
Hadi V, Norouzy A, Mazaheri Tehrani M, Nematy M, Hadi S. Characteristics of compact food bars. J Nutr Fasting Health 2018;6:125-31.
Sindiani M, Eliakim A, Segev D, Meckel Y. The effect of two different interval-training programmes on physiological and performance indices. Eur J Sport Sci 2017;17:830-7.
Farrell S, Ivy J. Lactate acidosis and the increase in VE/VO2 during incremental exercise. Journal of Applied Physiology 1987;62:1551-5.
Enright SJ, Unnithan VB. Effect of inspiratory muscle training intensities on pulmonary function and work capacity in people who are healthy: A randomized controlled trial. Phys Ther 2011;91:894-905.
Habedank D, Reindl I, Vietzke G, Bauer U, Sperfeld A, Gläser S, et al. Ventilatory efficiency and exercise tolerance in 101 healthy volunteers. European journal of applied physiology and occupational physiology 1998;77:421-6.
Durmic T, Lazovic B, Djelic M, Lazic JS, Zikic D, Zugic V, et al.
Sport-specific influences on respiratory patterns in elite athletes. J Bras Pneumol 2015;41:516-22.
Davis JM, Carlstedt CJ, Chen S, Carmichael MD, Murphy EA. The dietary flavonoid quercetin increases VO (2 max) and endurance capacity. Int J Sport Nutr Exerc Metab 2010;20:56-62.
Sachan DS, Hongu N. Increases in VO2 max and metabolic markers of fat oxidation by caffeine, carnitine, and choline supplementation in rats. J Nutr Biochem 2000;11:521-6.
Gharahdaghi N, Shabkhiz F, Azarboo E, Keyhanian A. The effects of daily coenzyme Q10 supplementation on VO2 max, vVO2 max and intermittent exercise performance in soccer players. Life Sci J 2013;10:22-8.
Ignjatović A, Hofmann P, Radovanović D. Non-invasive determination of the anaerobic threshold based on the heart rate deflection point. Facta Univ Ser Phys Educ Sport 2008;6:1-10.
Moazami M, Taghizadeh V, Ketabdar A, Dehbashi M, Jalilpour R. Effects of oral L-arginine supplementation for a week, on changes in respiratory gases and blood lactate in female handballists. Iran J Nutr Sci Food Technol 2015;9:45-52.
Paes LS, Borges JP, Cunha FA, Souza MG, Cyrino FZ, Bottino DA, et al.
Oxygen uptake, respiratory exchange ratio, or total distance: A comparison of methods to equalize exercise volume in Wistar rats. Braz J Med Biol Res 2016;49:1-8.
Kemps HM, Schep G, Zonderland ML, Thijssen EJ, De Vries WR, Wessels B, et al.
Are oxygen uptake kinetics in chronic heart failure limited by oxygen delivery or oxygen utilization? Int J Cardiol 2010;142:138-44.
Hennigar SR, Gaffney-Stomberg E, Lutz LJ, Cable SJ, Pasiakos SM, Young AJ, et al.
Consumption of a calcium and vitamin D-fortified food product does not affect iron status during initial military training: A randomised, double-blind, placebo-controlled trial. Br J Nutr 2016;115:637-43.
Kennedy SJ, Ryan L, Clegg ME. The effects of a functional food breakfast on gluco-regulation, cognitive performance, mood, and satiety in adults. Nutrients 2020;12:2974.
Lamport DJ, Dye L, Wightman JD, Lawton CL. The effects of flavonoid and other polyphenol consumption on cognitive performance: A systematic research review of human experimental and epidemiological studies. Nutr Aging 2012;1:5-25.
Malek MH, Housh TJ, Coburn JW, Beck TW, Schmidt RJ, Housh DJ, et al.
Effects of eight weeks of caffeine supplementation and endurance training on aerobic fitness and body composition. J Strength Cond Res 2006;20:751-5.
Hadi V, Ghayour Mobarhan M, Ranjbar G, Sardar MA, Dabbagh Moghaddam A, Nematy M, et al.
Effect of a designed compact food bar on maximal oxygen uptake (VO2 Max) and exercise performance in military athletes: A randomized, single-blind, placebo-controlled clinical trial. Iran Red Crescent Med J 2020;22:1-7.
Krauss RM, Eckel RH, Howard B, Appel LJ, Daniels SR, Deckelbaum RJ, et al.
AHA Dietary Guidelines: Revision 2000: A statement for healthcare professionals from the Nutrition Committee of the American Heart Association. Circulation 2000;102:2284-99.
Pahlavani N, Entezari MH, Nasiri M, Miri A, Rezaie M, Bagheri-Bidakhavidi M, et al.
The effect of l-arginine supplementation on body composition and performance in male athletes: A double-blinded randomized clinical trial. Eur J Clin Nutr 2017;71:544-8.
Hogervorst E, Bandelow S, Schmitt J, Jentjens R, Oliveira M, Allgrove J, et al.
Caffeine improves physical and cognitive performance during exhaustive exercise. Med Sci Sports Exerc 2008;40:1841-51.
Schulman SP, Becker LC, Kass DA, Champion HC, Terrin ML, Forman S, et al. L-arginine therapy in acute myocardial infarction: the Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) randomized clinical trial. Jama 2006;295:58-64.
Santos R, Pacheco M, Martins R, Villaverde A, Giana H, Baptista F, et al.
Study of the effect of oral administration of L-arginine on muscular performance in healthy volunteers: An isokinetic study. Isokinetics Exerc Sci 2002;10:153-8.
Jafari A, Nik KJ, Malekirad A. Effect of short-term caffeine supplementation on downhill running induced inflammatory response in non-athletes males. J Cell & Tissue 2012;2:377-385.
Laursen PB, Jenkins DG. The scientific basis for high-intensity interval training: Optimising training programmes and maximising performance in highly trained endurance athletes. Sports Med 2002;32:53-73.
Davis JK, Green JM. Caffeine and anaerobic performance: Ergogenic value and mechanisms of action. Sports Med 2009;39:813-32.
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]