Effects of Six Weeks of Watermelon Juice supplementation on Total Antioxidant Capacity in Elite Taekwondo Athletes

doi:10.21203/rs.3.rs-5255062/v1

Introduction and objective:The natural product watermelon contains a high concentration of antioxidants that have the potential to mitigate the oxidative damage resulting from the generation of free radicals post-exercise. As such, this study aims to explore the impact of six weeks of watermelon juice supplementation on the antioxidant capacity of elite female taekwondo athletes.

Methods: In a study involving twenty-five young female elite taekwondo players with a mean age of 21.84±2.26 years, participants were randomly assigned to either the watermelon juice group (n=15) or the placebo group (n=10). Over six weeks, subjects consumed 500 ml of watermelon juice or placebo 45 minutes before each of their three weekly training sessions. The Total Antioxidant Capacity (TAC) index was measured in selected athletes undergoing training at the Taekwondo House in Kermanshah, located in western Iran.

Results: The study found that following six weeks of intervention, watermelon juice supplementation led to a significant increase in total antioxidant capacity (TAC) (p=0.001), while the TAC levels in the placebo (PLA) group remained relatively unchanged (p=0.490). Moreover, participants in the watermelon juice group demonstrated higher VO2max compared to the placebo group, and experienced significantly lower levels of muscle soreness at 24 and 48 hours post-exercise (p>0.05).

Conclusions: A six-week regimen of watermelon juice supplementation has been found to enhance overall antioxidant capacity and alleviate muscle soreness.

Watermelon Juice

Total antioxidant capacity

muscle soreness

Taekwondo

One of the primary considerations for sustaining peak performance during physical activity is the effective management of fatigue. Fatigue can stem from various factors that hinder athletic performance and disrupt the energy production (1). "Researchers, physiologists, and athletes have been seeking innovative and effective dietary strategies to mitigate these adverse effects, as nutrition, hydration, and physical activity are interconnected (2–4).

In contemporary times, athletes commonly incorporate various types of sports drinks into their regimen. In contrast to plain water, sports drinks offer added advantages to athletes due to their composition of diverse macro- and micronutrients such as carbohydrates, vitamins, and electrolytes. These components play a pivotal role in enhancing energy production, facilitating glycogen replenishment and rehydration, delaying fatigue, and improving neuromuscular functions (2, 5).

Through the implementation of exercise, the body's metabolism increases, resulting in elevated oxygen consumption. This, in turn, disrupts to an imbalance in the human body homeostasis (6). Leukocytes in muscle tissue have the capacity to generate reactive oxygen species (ROS) and cytokines can trigger the activation of ROS-producing enzymes (7). Oxidative stress, a condition characterized by an imbalance between the production of free radicals and the antioxidant defense capacity, is associated with cell damage, chronic diseases, immune dysfunction, muscle fatigue, muscle injury, and overtraining, particularly when accompanied by inadequate recovery (8, 9). Under normal physiological conditions, the body's cellular antioxidant defense system works to eliminate damaged molecules (8). However, in cases of excessive ROS production, this balance is disrupted, leading to oxidative stress (7). The body employs various endogenous antioxidant defense mechanisms to counteract oxidative stress (8), with dietary antioxidants playing a significant role. Some studies suggest that antioxidant supplements effectively mitigate exercise-induced oxidative stress and muscle damage (10).

Current scholarly research has primarily focused on the impact of dietary antioxidants on exercise-induced muscle damage rather than on athletic performance (11, 12). Studies have also been conducted to evaluate the potential effects of dietary antioxidants, such as those found in watermelon, on total antioxidant capacity (TAC) following strenuous exercise (13, 14). Watermelon, which is native to Africa and belongs to the family Cucurbitaceae, is now extensively cultivated in tropical regions worldwide. Iran and several other countries are the largest producers, yielding an annual global output of 29.6 million tons (15).

Watermelon is popular not only as a fruit but also as a beverage among athletes due to its antioxidant properties. Numerous studies have shown that watermelon is abundant in antioxidants (13, 16–21). It is considered a natural juice without added sugar and rich in bioactive compounds that can offer health and performance benefits to athletes. Supporting this notion, a review study by Naz et al. (2014) revealed that watermelon contains a variety of nutrients, including lycopene, Beta-Carotene, Glutathione, citrulline, Ascorbic acid, amino acids, water (92%), carbohydrates, fiber, vitamins A and C, thiamine, riboflavin, niacin, folate, magnesium, potassium, calcium, phosphorus, and iron (15). The red color of watermelon is rich in lycopene, and it has been demonstrated that glutathione, lycopene, beta carotene, and vitamins C present in watermelon help eliminate free radicals (13). Several studies have indicated a significant positive effect after athletes consumed watermelon juice. Overall, through a specific mechanism, watermelon can enhance athletic performance (22–26). Therefore, the consumption of natural fruit juice is highly desirable not only for providing carbohydrates but also for maintaining performance and health.

No research has been conducted to examine the impact of watermelon juice consumption on the cognitive functions of female elite Taekwondo athletes. Consequently, our hypothesis suggests that a six-week regimen of watermelon juice supplementation may enhance total antioxidant capacity (TAC) and reduce muscle soreness in female elite Taekwondo athletes.

Subjects

Twenty-five professional female taekwondo athletes volunteered to participate in this study (Table 1). Exclusion criteria included taking any kind of protein supplements and having any acute or chronic disease (especially food allergies or sensitivity). The participants were also required to have a minimum of 5 years of Taekwondo training experience and at least one top-3 placing at national competitions. After receiving the required information regarding the intervention and its potential benefits, they completed a written informed consent form. The study protocols were approved by the Ethics committee of Kermanshah University of Medical Sciences (IR.KUMS.REC.1397.739) and registered Code IRCT2019101013045088n1 by the Center of Clinical Trial.

Table1: Anthropometric subject's Mean ± standard deviation
characteristics
Age (years)	21.78±2.27
Height (cm)		168.6±65.44
Weight (kg)	59.55±49.66
BMI (kg/m²)	20.05±86.42
Body Fat (%)	19.01±81.02
Vo2max (ml/kg/min)	39.70±76.85
CM: centimeter; kg: kilogram; BMI; body mass index

Experimental design

A randomized one-blinded design was used in this research. Before the start of the experiment, Subjects were familiarized with all performance tests to eliminate any order effects. On the first visit to the laboratory, body composition and VO_2max, were obtained. Body composition analysis was measured with Inbody; ZEUS 9.9 made by Korea. A graded exercise test (Astrand) on an electronically-braked cycle ergometer (Monark Ergomedice 839E model) was completed to evaluate vo2max in the laboratory of the faculty of Sports Sciences, Razi University, Iran. Subjects were required to complete Eighteen sessions in 6 weeks with either a watermelon juice (WJ) (500m/l pure watermelon juice) or placebo (PLA) (500 m/l water with Stevia's non-nutritious sweetener and natural edible color). The main exercise included 500 m/l WJ or PLA ingestion 45 minutes before performing the taekwondo exercises. All tests were performed at the same time of the day (between 5 p.m. and 6 p.m.). Taekwondo training included a 15-minute dynamic warm-up (stretching exercises of the upper and lower limbs, dynamic movements like marching, pelvis and leg and waist movements, and jumping movements including jumping and hopping), and the dedicated exercise held up for subjects during 90 minutes in each session, diversely. At the end of each exercise session, the participants performed a 10-minute cooldown including stretching exercises. Subjects' dietary's plan and daily energy intake were calculated by the software (N4) during this research (27). The macronutrients intake is presented in the table2. The participants were also given a list of nitrate-containing items (Tomato, beetroot, garlic, seafood, brown rice, parmesan cheese, dairy, dark chocolate and nuts)to avoid for three days before and during the course of the study. (2), and each subject was also asked to avoid drinking coffee or any caffeinated beverage or doing any intensive exercise 24 hours before each exercise trial.

Table 2. subject's percentage of macronutrients intake
CHO %	56.125
PROTEIN %	20.875
FAT %	23.250
Total caloric	2817.05

Muscle Soreness

At the end of each session during this six weeks (Watermelon juice or placebo), the subjects self-reported their soreness 24 and 48 h after the physical exertion on a scale questionnaire from 1 to 5 as follows: 1, no soreness; 2, minimal soreness with no impact on immediate training; 3, medium soreness with minimal impact on immediate training; 4, high soreness with negative impact on immediate training; 5, maximum soreness with physical disability for immediate training (27, 28).

Supplement

Since the content of watermelon varies based on type of the watermelon and its brix (29). Thus, for the supplement's content to be the same in density, flavor, and appearance during the course of the study, Watermelon juice brix was measured by Refractometer prior to preparing the watermelon juice for each session. The watermelons with 9-12 brix were selected in this research protocol. (28, 30, 31). Watermelon juice was prepared by a home-made juicer using watermelons with removed seeds while the placebo was prepared by using natural edible red food color and stevia (Non-nutritive sweetener), and they added to 500ml of water. The phytochemical content of fresh watermelon juice per 100 g is presented in Table 3 (32, 33)

Table 3. Phytochemical content of fresh watermelon juice per 100 g
Parameter	Unit	Value	Reference

Water	g	91.8	[32]
Energy	Kcal	30-46.2	[33]
Carbohydrate	g	7.6-11.6	[33]
Protein	g	0.6-0.9	[33]
Total fat	g	0-0.15	[33]
Cholestrol	Mg	0.00-0.01	[33]
Dietary fibr	G	0.4-0.61	[33]
Vitamine A	IU	569-864.88	[33]
Vitamin C	Mg	8.1-12.31	[33]
Lycopene	Mg	3.38-11.34	[33]
Sodium	-	0.0-0.001	[33]
Ash	%	5.2-5.4	[33]
Moisture	%	93.12-95.2	[33]
Calcium	Mg	7	[33]
Iron	Mg	0.24	[33]
Magnesium	Mg	10	[33]
Potassium	Mg	112	[33]
Phosphorus	Mg	11	[33]

Blood sampling

Blood samples were collected twice during the study. Participants visited the laboratory between 07:00 and 08:00 A.M after a 10-12 hour fasting period. The first sample was obtained from the brachial vein after 5 minutes of rest in the supine position. The second sample was taken 48 hours after a 6-week complementary intervention followed by a taekwondo session, under the same conditions as the first blood sampling. In both instances, 10 ml of blood was drawn and transferred to EDTA tubes. The blood samples were then centrifuged at 4000 revolutions per minute for 10 minutes. The plasma samples were stored at room temperature, while the serum samples were placed at 27°C. Total Antioxidant Capacity (TAC) was assessed using the Germany Zell Baiokit and an automatic ELISA system.

Statistical Analysis

Statistically significant was considered set at p≤0.05. Data are presented as mean ± standard deviation. Shapiro-Wilk test was used for normal data distribution. Independent T-test was used to assess the intra-group differentiations and dependent T-test was used to investigate the inter-group differentiations. Spss application version 25 was used for data analysis.

Macronutrients (carbohydrates, lipids, and proteins) and daily energy consumption did not change significantly during this study. On the other, watermelon juice or placebo did not cause any gastrointestinal discomfort or allergic reactions in the subjects. TAC was 1.00 ± 47.147 received to 1.00 ± 61.145 m/mol for WJ, 1.00 ± 48.195 received to 1.00 ± 44.175 m/mol for PLA treatment. There was a significant difference between pre and post groups of WJ after six weeks watermelon juice ingestion (p ≤ 0.001), (Fig. 1). However, placebo groups didn’t have any significant increase in TAC (p = 0.490). muscle soreness was on base that how they are feeling 24 and 48 hours after training session. Also, we observed a significantly greater after 24–48 hours behind training session in WJ compared to the PLA group (p ≤ 0.05). Nevertheless, after 48 hours, PLA Group had experienced a decrease muscle soreness but not all of them didn't get to 1 that it was not significantly difference (p ≤ 0.05), (Fig. 2).

The key finding of this study is that the ingestion of 500 mL of watermelon juice over a six-week period (on odd days) may significantly increase the Total Antioxidant Capacity (TAC) of elite female taekwondo players. Furthermore, those who consumed watermelon juice experienced decreased muscle soreness after 24 and 48 hours. This suggests that exercising after ingesting watermelon juice may further reduce fatigue compared to a placebo. Free radicals, which are highly reactive molecules with unpaired electrons in their outer layer, can cause oxidative stress and muscular damage, leading to a decline in muscular power, impaired performance, and reduced time to exhaustion (34). Watermelon juice contains glutathione, a potent antioxidant that, along with L-citrulline, affects vasodilation by expanding smooth endothelial vascular muscles, ultimately leading to smooth muscle relaxation, balanced blood flow, improved muscle energy metabolism, and enhanced mitochondrial respiration during exercise, thereby improving athletic performance (35). To date, there is almost no research that refutes the effect of watermelon juice ingestion on TAC.

However, many studies have shown that watermelon juice ingestion at different times and dosages leads to improved antioxidant capacity in athletes. This claim is in line with Martha et al. (2013), shanely et al. (2013), Maoto et al. (2019), and Ozcelik et al. (2016) studies (28, 32, 33, 36). These findings are in some ways similar to those previously reported by some other studies (2, 16, 28, 37–39). In a study by Edwards et al. (2003), it has been shown that watermelon juice consumption increases the levels of lycopene and beta-carotene in the watermelon group rather than the placebo group (21). Pinto et al. (2011) showed in an investigation of the level of watermelon lycopene content and antioxidant capacity that red flesh of watermelon is one of the main dietary sources of lycopene which contains the highest carotenoids and decreases the prostate cancer risk (13). Ridwan et al. (2019) investigated supplementation of 100% flesh watermelon juice prior to swimming exercise for 14 days in rats. They discovered that rats that were given 100 percent flesh watermelon juice swam for considerably longer periods before exhaustion (40).

Lycopene, a potent antioxidant, exhibits twice the protective capacity of β-carotene and α-tocopherol against cellular damage caused by free radicals. Its ability to suppress singlet oxygen is noteworthy. Plasma lycopene levels vary significantly due to diverse dietary practices across different geographical regions (41). Abundant in watermelon (42), lycopene is a non-provitamin carotenoid. Carotenoids, known for their highly efficient scavenging of singlet oxygen (1O2) and other excited species, transfer energy from 1O2 to the lycopene molecule during 1O2 quenching, resulting in its conversion to an energy-rich triplet state. Lycopene in the triplet state can revert to its original state by releasing energy in the form of heat or physical extinction, thus preserving the integrity of the lycopene molecule for further neutralization. Lycopene also serves as an exceptional 1O2 solvent in biological membrane models such as liposomes. However, trapping other active oxygen species like OH, NO2, or peroxynitrite results in the oxidative degradation of the lycopene molecule (41).

Generally, high-intensity exercise causes an increase in the production of metabolic by-products such as free radicals and increases oxidative stress. Thus, probably 500 ml of watermelon juice has enough amino acids, vitamins and antioxidants content to help reduce muscle soreness. It's also notable that after 48 hours, muscle soreness decreased in both groups, but this decrease was only significant in the WJ group.

Based on the findings of this study and prior research, it is suggested that watermelon juice could serve as a natural sports beverage due to its significant antioxidant properties, which may help alleviate exercise-induced muscle damage. Our hypothesis posited that consuming watermelon juice 45 minutes before taekwondo training over a 6-week period could elevate Total Antioxidant Capacity (TAC), reduce muscle soreness, and enhance athletic performance. Consequently, it may be advisable to recommend watermelon juice to athletes as an ergogenic aid to enhance the threshold for muscular pain and improve both sports performance and post-exercise blood factors.

limitations

The study also included a list of nitrate-containing foods that participants were advised to avoid, although it remains unclear to what extent the participants adhered to this recommendation. Therefore, future investigations should incorporate a more comprehensive range of assessments to thoroughly evaluate muscle soreness, fatigue, and performance changes. Furthermore, future studies could benefit from implementing stricter dietary monitoring and potentially prescribing individualized nutrition plans for participants. Additionally, there is a need for further research to compare the effects of different dosages of watermelon juice on various factors such as muscle soreness, performance, and total antioxidant capacity (TAC).

The significant outcome of the study indicates that the prolonged consumption of 500 ml of watermelon juice over a six-week period prior to Taekwondo training sessions has the potential to enhance antioxidant capacity and reduce muscle soreness 24 and 48 hours post-exercise. The research suggests that the ingestion of watermelon juice may elevate antioxidant capacity levels and eliminate resulting free radicals, potentially leading to improved exercise performance.

Conflict of Interest Statement:

The authors declare no conflict of interest.

Consent to participate:

Informed consent was obtained from all individual participants included in the study.

Declaration of Competing Interest:

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Funding:

The authors declared that the research did not receive any financial grants.

Author Contribution

PAA and MA contributed to the conception and design of the research; PAA, MA, and WT contributed to data collection; MA and WT contributed to the acquisition and analysis of the data; MA and WT contributed to the interpretation of the data; PAA, MA, and WT contributed to draft the manuscript. All authors agree with the manuscript and declare that the content has not been published elsewhere.

Acknowledgments:

We appreciate all the subjects who participated in the present research.

Pooyandjoo M, Nouhi M, Shab-Bidar S, Djafarian K, Olyaeemanesh A. The effect of (L-) carnitine on w eight loss in adults: a systematic review and meta-analysis of randomized controll edtrials. Ендокринологія. 2018;23(1):83-90.
Bailey SJ, Blackwell JR, Williams E, Vanhatalo A, Wylie LJ, Winyard PG, et al. Two weeks of watermelon juice supplementation improves nitric oxide bioavailability but not endurance exercise performance in humans. Nitric Oxide. 2016;59:10-20.
Grala A, Candellório É, Sperandio P, Maldonado E, dos Anjos B, Jacinto J, et al. Effects of Citrulline Malate Supplementation on Aerobic and Muscular Endurance in Young Adults Men. Journal of Health Sciences. 2021;23(1):72-8.
Rao AV, Rao LG. Carotenoids and human health. Pharmacological research. 2007;55(3):207-16.
Shalesh FJ, Hasan UC, Jaaz AF. The effect of sport drink on some functional variables for soccer players. Internasional Journal Of Advanced Research. 2014;2(2):868-75.
Draeger CL, Naves A, Marques N, Baptistella AB, Carnauba RA, Paschoal V, et al. Controversies of antioxidant vitamins supplementation in exercise: ergogenic or ergolytic effects in humans? Journal of the International Society of Sports Nutrition. 2014;11(1):1-4.
Ives SJ, Bloom S, Matias A, Morrow N, Martins N, Roh Y, et al. Effects of a combined protein and antioxidant supplement on recovery of muscle function and soreness following eccentric exercise. Journal of the International Society of Sports Nutrition. 2017;14(1):1-10.
Gravina L, Ruiz F, Diaz E, Lekue JA, Badiola A, Irazusta J, et al. Influence of nutrient intake on antioxidant capacity, muscle damage and white blood cell count in female soccer players. Journal of the International Society of Sports Nutrition. 2012;9(1):1-11.
Finaud J, Lac G, Filaire E. Oxidative stress. Sports medicine. 2006;36(4):327-58.
Devasagayam T, Tilak J, Boloor K, Sane KS, Ghaskadbi SS, Lele R. Free radicals and antioxidants in human health: current status and future prospects. Japi. 2004;52(794804):4.
Braakhuis AJ, Hopkins WG. Impact of dietary antioxidants on sport performance: a review. Sports Medicine. 2015;45(7):939-55.
Margonis K, Fatouros IG, Jamurtas AZ, Nikolaidis MG, Douroudos I, Chatzinikolaou A, et al. Oxidative stress biomarkers responses to physical overtraining: implications for diagnosis. Free Radical Biology and Medicine. 2007;43(6):901-10.
Pinto P, Santos C, Henriques C, Basto de Lima MG, de Fátima Quedas M. Lycopene content and antioxidant capacity of Portuguese watermelon fruits. Electronic Journal of Environmental, Agricultural and Food Chemistry. 2011:2090-7.
Naz A, Butt MS, Pasha I, Nawaz H. Antioxidant indices of watermelon juice and lycopene extract. Pak J Nutr. 2013;12(3):255-60.
Naz A, Butt MS, Pasha I, Nawaz H. Antioxidant indices of watermelon juice and lycopene extract. Pakistan Journal of Nutrition. 2013;12(3):255.
Rizal M, Segalita C, Mahmudiono T. The effect of watermelon beverage ingestion on fatigue index in young-male, recreational football players. Asian Journal of Sports Medicine. 2019;10(2).
Martinez-Sanchez A, Alacid F, Rubio-Arias JA, Fernandez-Lobato B, Ramos-Campo DJ, Aguayo E. Consumption of watermelon juice enriched in L-citrulline and pomegranate ellagitannins enhanced metabolism during physical exercise. Journal of agricultural and food chemistry. 2017;65(22):4395-404.
Shanely RA, Nieman DC, Perkins-Veazie P, Henson DA, Meaney MP, Knab AM, et al. Comparison of watermelon and carbohydrate beverage on exercise-induced alterations in systemic inflammation, immune dysfunction, and plasma antioxidant capacity. Nutrients. 2016;8(8):518.
Naz A, Butt MS, Sultan MT, Qayyum MMN, Niaz RS. Watermelon lycopene and allied health claims. EXCLI journal. 2014;13:650.
Tarazona‐Díaz MP, Viegas J, Moldao‐Martins M, Aguayo E. Bioactive compounds from flesh and by‐product of fresh‐cut watermelon cultivars. Journal of the Science of Food and Agriculture. 2011;91(5):805-12.
Edwards AJ, Vinyard BT, Wiley ER, Brown ED, Collins JK, Perkins-Veazie P, et al. Consumption of watermelon juice increases plasma concentrations of lycopene and β-carotene in humans. The Journal of nutrition. 2003;133(4):1043-50.
Figueroa A, Wong A, Jaime SJ, Gonzales JU. Influence of L-citrulline and watermelon supplementation on vascular function and exercise performance. Current opinion in clinical nutrition and metabolic care. 2017;20(1):92-8.
Aguayo E, Martínez-Sánchez A, Fernández-Lobato B, Alacid F. L-Citrulline: A Non-Essential Amino Acid with Important Roles in Human Health. Applied Sciences. 2021;11(7):3293.
Su Q-S, Tian Y, Zhang J-G, Zhang H. Effects of allicin supplementation on plasma markers of exercise-induced muscle damage, IL-6 and antioxidant capacity. European journal of applied physiology. 2008;103(3):275-83.
Meydan D, Gursel B, Bilgici B, Can B, Ozbek N. Protective effect of lycopene against radiation-induced hepatic toxicity in rats. Journal of International Medical Research. 2011;39(4):1239-52.
Mohamed MI, Mohammad MKA, Zakaria AM, Ghazali N, Isa MM, Razak HRA, et al. Induction of oxidative stress following low dose ionizing radiation in ICR mice. World Journal of Medical Sciences. 2014;10(2):198-203.
Pérez-Guisado J, Jakeman PM. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. The Journal of Strength & Conditioning Research. 2010;24(5):1215-22.
Tarazona-Díaz MP, Alacid F, Carrasco M, Martínez I, Aguayo E. Watermelon juice: potential functional drink for sore muscle relief in athletes. Journal of agricultural and food chemistry. 2013;61(31):7522-8.
Rimando AM, Perkins-Veazie PM. Determination of citrulline in watermelon rind. Journal of Chromatography A. 2005;1078(1-2):196-200.
Ali A, Moss C, Yoo MJY, Wilkinson A, Breier BH. Effect of mouth rinsing and ingestion of carbohydrate solutions on mood and perceptual responses during exercise. Journal of the International Society of Sports Nutrition. 2017;14(1):4.
Martínez-Sánchez A, Ramos-Campo DJ, Fernández-Lobato B, Rubio-Arias JA, Alacid F, Aguayo E. Biochemical, physiological, and performance response of a functional watermelon juice enriched in L-citrulline during a half-marathon race. Food & nutrition research. 2017;61(1):1330098.
Ozcelik B, Yavuz M. Watermelon Juice. Handbook of Functional Beverages and Human Health: CRC Press; 2016. p. 577-86.
Maoto MM, Beswa D, Jideani AI. Watermelon as a potential fruit snack. International Journal of Food Properties. 2019;22(1):355-70.
Mohammad MKA, Mohamed MI, Zakaria AM, Razak A, Rashmizal H, Saad WMM. Watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice modulates oxidative damage induced by low dose X-ray in mice. BioMed research international. 2014;2014.
Suzuki T, Morita M, Kobayashi Y, Kamimura A. Oral L-citrulline supplementation enhances cycling time trial performance in healthy trained men: Double-blind randomized placebo-controlled 2-way crossover study. Journal of the International Society of Sports Nutrition. 2016;13(1):1-8.
Shanely R, Nieman D, Perkins-Veazie P, Henson D, Meaney M, Knab A, et al. Comparison of watermelon and carbohydrate beverage on exercise-induced alterations in systemic inflammation, immune dysfunction, and plasma antioxidant capacity. Nutrients. 2016;8(8):518.
Martínez-Sánchez A, Ramos-Campo DJ, Fernández-Lobato B, Rubio-Arias JA, Alacid F, Aguayo E. Biochemical, physiological, and performance response of a functional watermelon juice enriched in L-citrulline during a half-marathon race. Food & Nutrition Research. 2017.
Blohm K, Beidler J, Rosen P, Kressler J, Hong MY. Effect of acute watermelon juice supplementation on post-submaximal exercise heart rate recovery, blood lactate, blood pressure, blood glucose and muscle soreness in healthy non-athletic men and women. International journal of food sciences and nutrition. 2020;71(4):482-9.
Chappell AJ, Allwood DM, Johns R, Brown S, Sultana K, Anand A, et al. Citrulline malate supplementation does not improve German Volume Training performance or reduce muscle soreness in moderately trained males and females. Journal of the International Society of Sports Nutrition. 2018;15(1):1-10.
Ridwan R, Razak HRA, Adenan MI, Saad WMM. Supplementation of 100% flesh watermelon [Citrullus lanatus (Thunb.) matsum. and nakai] juice improves swimming performance in rats. Preventive nutrition and food science. 2019;24(1):41.
Wertz K, Siler U, Goralczyk R. Lycopene: modes of action to promote prostate health. Archives of biochemistry and biophysics. 2004;430(1):127-34.
Lee M, Lin W, Yu B, Lee T. Antioxidant capacity of phytochemicals and their potential effects on oxidative status in animals—A review. Asian-Australasian journal of animal sciences. 2017;30(3):299.

No competing interests reported.

Effects of Six Weeks of Watermelon Juice supplementation on Total Antioxidant Capacity in Elite Taekwondo Athletes

Status:

Version 1

Abstract

Figures

Introduction

Methods

Results

Discussion

limitations

Conclusion

Declarations