The Effect of Citrulline/Malate on Blood Lactate Levels in Intensive Exercise

Efficacy of amino acids in sports nutrition- review of clinical evidences

The efficacy of amino acids as popular sports supplements has triggered debates, with their impact on athletic performance varying across sports disciplines due to diversity and heterogeneity in clinical trials. This review evaluates the ergogenic potential of amino acids, by critical appraisal of results of clinical trials of Branched chain amino acids (BCAAs), arginine, glutamine, citrulline, β-alanine, and taurine, performed on elite sportsmen from various land and water sports. Clinical trials reviewed here confirm notable physiological benefits thereby supporting the claim that BCAA, citrulline and arginine in various doses can have positive effects on endurance and overall performance in sportsperson. Furthermore, results of clinical trials and metabolomic studies indicate that in future it would be more beneficial to design precise formulations to target the requirement of specific sports. For instance, some combinations of amino acids may be more suitable for long term endurance and some others may be suitable for short burst of excessive energy. The most important insights from this review are the identification of three key areas where research is urgently needed: a) Biomarkers that can identify the physiological end points and to distinguish the specific role of amino acid as anti-fatigue or reducing muscle soreness or enhancing energy b) In-depth sports-wise clinical trials on elite sportsperson to understand the ergogenic needs for the particular sports c) Design of precision formula for similar types of sports instead of common supplements.

Effects of branched chain amino acids, l-citrulline, and alpha-glycerylphosphorylcholine supplementation on exercise performance in trained cyclists: a randomized crossover trial

BACKGROUND

Nutrition plays a key role in training and athletic performance and dietary supplements can make a small, but potentially valuable, contribution to achieving peak athletic performance. This study is the first to investigate the effects of supplementation from the combination of BCAAs, L-citrulline, and A-GPC on exercise performance.

METHODS

In this randomized, double-blind, crossover study 30 male trained cyclists (age: 43.7 ± 8.5 years) completed a 20 km cycling time trial (TT) test and a high intensity endurance cycling (HIEC) test following a 7-day supplementation period with either a supplement containing 8 g BCAAs, 6 g L-citrulline, and 300 mg A-GPC or a placebo (15 g maltodextrin). For each trial, mean values for time to completion, peak and average power output, OMNI rating of perceived exertion, and visual analogue scale (VAS) responses on perceived exertion were computed for the 20 km TT test. Mean values for time to fatigue and VAS responses on perceived exertion were computed for the HIEC test. Procedures for dietary intake and exercise patterns were implemented to achieve consistency throughout the study period.

RESULTS

There was a significant increase (p = .003) in peak power in the 20 km TT (354.27 ± 87.88 and 321.67 ± 63.65, for supplement and placebo trials, respectively) and a significant increase (p = .001) in time to fatigue in the HIEC test (0:19:49 ± 0:11:13 min and 0:14:33 ± 0:09:59 min, for supplement and placebo trials, respectively) with the test supplement compared to the placebo. With the test supplement, there was an average increase in TT peak power of 11% and an average increase in time to fatigue of 36.2% in the HIEC test compared to the placebo. There was no significant improvement in time to completion, average power, OMNI rating of perceived exertion, or VAS responses on perceived exertion in the TT test and no significant improvement in VAS measures of perceived exertion in the HIEC test.

CONCLUSIONS

The combination of BCAAs, L-citrulline, and A-GPC used in this study improves cycling performance and may be useful for individuals seeking to improve athletic performance, particularly in disciplines requiring lower body muscular strength and endurance.

Effects of citrulline on endurance performance in young healthy adults: a systematic review and meta-analysis

BACKGROUND

Citrulline is a popular dietary supplement, primarily thought to exert ergogenic effects on exercise performance through the enhancement of nitric oxide (NO) synthesis and ammonia buffering. However, recent findings surrounding citrulline's effect on endurance performance have been inconsistent. A systematic review and meta-analysis of the relevant literature have yet to be undertaken.

AIM

To determine if acute ingestion of citrulline has an ergogenic effect on endurance performance in young healthy adults.

METHODS

A systematic search of three databases was undertaken to find peer-reviewed randomized controlled trials (RCTs) published in English investigating the effects of citrulline supplementation on endurance performance in young healthy adults. Two independent investigators completed a three-phased screening procedure against pre-determined eligibility criteria. Included studies evaluated loading or bolus dosage regimes of citrulline in participants aged 18 or over that were at least recreationally active. Outcome measures focused on time-to-completion (TTC) or time-to-exhaustion (TTE) in continuous submaximal intensity exercise. Cochrane's Risk of Bias 2 (RoB 2) tool was used to assess the risk of bias in individual studies. Meta-analysis was conducted using a fixed-effects model to pool the weighted estimate of standardized mean differences (SMD) across studies. A chi-squared test assessed heterogeneity between studies. This review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Nine studies (n = 158 participants) met the eligibility criteria; five reported TTE outcomes (I² = 0%, χ² = 0.37, df = 4, P = 0.99) and four reported TTC outcomes (I² = 0%, χ² = 0.46, df = 3, P = 0.93), both with a low between-study heterogeneity. The results of the meta-analyses showed no significant difference in the endurance performance measures, TTE (pooled SMD = 0.03 [-0.27, 0.33]) and TTC (pooled SMD = -0.07 [-0.50, 0.15]), after acute ingestion of citrulline supplementation or a control in young healthy adults.

DISCUSSION

The current evidence suggests no significant benefit of citrulline supplementation for endurance performance. However, the small evidence base requires further research to fully evaluate this topic. Recommendations include a focus on female populations; higher continuous doses of citrulline over seven days; and TTC outcome measures over longer distances to simulate competition.

The Effect of a Single Dose of Citrulline on the Physical Performance of Soccer-Specific Exercise in Adult Elite Soccer Players (A Pilot Randomized Double-Blind Trial)

PURPOSE

The purpose of this study was to evaluate the effect of a single intake of citrulline at 3 g and 6 g doses in adult elite soccer players performing sport-specific exercise.

MATERIALS AND METHODS

This randomized double-blind placebo-controlled study analyzed 18 soccer players from the top divisions of three European countries. Participants were randomized into three groups of six each and performed a field-based soccer-specific test for 18 min. Comparative analysis of heart rate, fatigue and post-exercise recovery was conducted.

RESULTS

There were no statistically significant differences in most of the analyzed parameters, nor at any of the time points for lactate concentration. Players' RPE exercise test score did not reveal any differences.

CONCLUSIONS

Neither a single intake of 3 g nor of 6 g of citrulline malate affected physical performance, subjective feelings of fatigue or post-exercise recovery in adult elite soccer players who performed a soccer-specific test.

The Effects of L-Citrulline on Blood-Lactate Removal Kinetics Following Maximal-Effort Exercise

The accumulation of lactate in muscle and blood during high-intensity exercise is negatively correlated with the duration exercise can be sustained. Removal of lactate is a key component of acute recovery between consecutive bouts of such exercise. Low-intensity exercise enhances recovery by accelerating lactate turnover in metabolically active tissues, largely mediated by blood flow to these tissues. Therefore, the purpose of this research was to clarify if L-citrulline, a nutritional supplement purported to promote vasodilation via enhanced nitric oxide availability, would augment the removal of blood lactate during active recovery (AR). L-citrulline ingestion will augment the rate of blood lactate concentration decrease during AR, reduce the oxygen-cost of submaximal exercise, and increase time-to-exhaustion and peak oxygen uptake (V̇O2peak) during a test of maximal aerobic power. Healthy university students (five males & five females) participated in this double-blind, randomized, placebo-controlled study. Participants exercised on a cycle ergometer at submaximal steady-state intensities followed by progressively increasing intensity to exhaustion, 10 min of AR, and then supramaximal intensity exercise to exhaustion. Oxygen uptake was measured throughout the trial and blood lactate was sampled repeatedly during AR. The protocol elicited very high peak blood lactate concentrations after exercise (11.3 + 1.3 mmol/L). L-citrulline supplementation did not significantly alter blood lactate kinetics during AR, the oxygen cost of exercise, V̇O2peak, or time-to-exhaustion. Despite a strong theoretical basis by which L-citrulline could augment lactate removal from the blood, L-citrulline supplementation showed no effect as an exercise-recovery supplement.

L-Citrulline: A Non-Essential Amino Acid with Important Roles in Human Health

L-Arginine (Arg) has been widely used due to its functional properties as a substrate for nitric oxide (NO) generation. However, L-citrulline (CIT), whose main natural source is watermelon, is a non-essential amino acid but which has important health potential. This review provides a comprehensive approach to different studies of the endogenous synthesis of CIT, metabolism, pharmacokinetics, and pharmacodynamics as well as its ergogenic effect in exercise performance. The novel aspect of this paper focuses on the different effects of CIT, citrulline malate and CIT from natural sources such as watermelon on several topics, including cardiovascular diseases, diabetes, erectile dysfunction, cancer, and exercise performance. CIT from watermelon could be a natural food-sourced substitute for pharmacological products and therefore the consumption of this fruit is promoted.

Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis

BACKGROUND

Citrulline is one of the non-essential amino acids that is thought to improve exercise performance and reduce post-exercise muscle soreness. We conducted a systematic review and meta-analysis to determine the effect of citrulline supplements on the post-exercise rating of perceived exertion (RPE), muscle soreness, and blood lactate levels.

METHODS

A random effects model was used to calculate the effect sizes due to the high variability in the study design and study populations of the articles included. A systematic search of PubMed, Web of Science, and ClinicalTrials.gov was performed. Eligibility for study inclusion was limited to studies that were randomized controlled trials involving healthy individuals and that investigated the acute effect of citrulline supplements on RPE, muscle soreness, and blood lactate levels. The supplementation time frame was limited to 2 h before exercise. The types and number of participants, types of exercise tests performed, supplementation protocols for L-citrulline or citrulline malate, and primary (RPE and muscle soreness) and secondary (blood lactate level) study outcomes were extracted from the identified studies.

RESULTS

The analysis included 13 eligible articles including a total of 206 participants. The most frequent dosage used in the studies was 8 g of citrulline malate. Citrulline supplementation significantly reduced RPE (n = 7, p = 0.03) and muscle soreness 24-h and 48-h after post-exercise (n = 7, p = 0.04; n = 6, p = 0.25, respectively). However, citrulline supplementation did not significantly reduce muscle soreness 72-h post-exercise (n = 4, p = 0.62) or lower blood lactate levels (n = 8, p = 0.17).

CONCLUSION

Citrulline supplements significantly reduced post-exercise RPE and muscle soreness without affecting blood lactate levels.

Use of Sports Supplements in Competitive Handball Players: Sex and Competitive Level Differences

Sports supplements are commonly used by elite athletes with the main goal of enhancing sport performance. Supplements use might be substantially different depending on the sport discipline, sex, and competitive level. To date, data about prevalence and the most-commonly used supplements in handball are scarce. Thus, the aim of this investigation was to determine the patterns of supplements use by handball players of both sexes and with different competitive levels: One hundred and eighty-seven handball players (112 men and 75 women) of different competitive levels (106 professional and 81 amateur) completed a validated self-administered questionnaire about supplements use. Supplements were classified according to the categorization of the Australian Institute of Sport (AIS). Overall, 59.9% of the handball players (n = 112) declared the use of at least one supplement and there were no significant differences between men and women (58.9% vs. 61.3%, p = 0.762) nor between professional vs. amateur handball players (67.1% vs. 53.8%, p = 0.074). The most prevalent supplements were sports drinks (42.2%), followed by energy bars (35.3%) and caffeine-containing products (31.6%). However, a greater consumption of group A supplements (those with strong scientific evidence; p = 0.029) and group B supplements (those with emerging scientific support, p = 0.012) was observed in male compared to female handball players. Supplements categorized as medical supplements were more commonly consumed in professional vs. amateur players (0.48 ± 0.80 vs. 0.21 ± 0.44, supplements p < 0.006). Additionally, a higher consumption of group B supplements was observed in professional compared to amateur players (0.58 ± 0.88 vs. 0.33 ± 0.72 supplements, p = 0.015). Handball players revealed a moderate use of supplements while sex and competitive level slighted changed the pattern of supplements use. A high portion of handball players use supplements as fuel during exercise and reported the use of caffeine-containing supplements to enhance performance.

[The effect of supplementation with L-arginine and L-citrulline on physical performance: a systematic review]

Introduction

Introduction: the amino acids L-arginine (L-arg) and L-citrulline (L-citr) have been used in sports nutrition, and it is believed that they have an effect on physical performance. However, current information is varied and inconclusive. Objective: to review and analyze the scientific evidence in the last ten years, which reflects a connection between the effect of L-arg and L-citr supplementation and physical performance. Material and method: this study is a systematic review of articles previously published, following the PRISMA model. Those articles published between 2008 and 2018 that connected the effect of L-arg and L-citr supplementation with physical performance were analyzed. The electronic search was performed on Web of Science, Scopus, Sport Discus, PubMed, and Medline. All articles using a supplementation protocol with these amino acids, separately or in groups, were selected. Results: a total of 38 articles were found, which were stratified according to the established protocol: a) supplementation with L-arg (n = 19); b) supplementation with L-arg and L-citr (n = 1); and c) supplementation with L-citr (n = 18), whether of short or prolonged duration. Conclusion: there is evidence that L-citr works better as ergogenic than L-arg does on physical performance, since L-citr showed a positive effect on the rate of perceived exertion and muscular pain, in addition to a decrease in lactate concentrations and time in maximum tests. However, there is not enough evidence to establish a beneficial L-citr dosage for physical performance.

Obesitas: Pentingkah Memperhatikan Konsumsi Makanan di Akhir Pekan?

Background: The prevalence of obesity in all age groups has increased in some countries. Epidemiological studies indicated that the intake of energy and macronutrient over the weekend were increasing rather than on weekdays and contributed to the incidence of obesity. Objectives: The aim of this literature review is to analyze the different between intake of energy and macronutrients in weekdays compared to weekend and how it contributes to obesity . Methode: The literature review method used international journal article that was searched using the electronic database such as Medline NCBI (National Center for Biotechnology Information), embases, and google scholar.Result: The results showed that energy and macronutrient intake were increasing over the weekend than on weekdays. Consumption of unhealthy food on weekend such as foods and beverages with high sugar, high fat and alcohol increase the energy and play a role in the incidence of obesity. Conclusion: The health promotion concerning food intake on weekdays and weekend both in terms of quantity and quality is needed for obesity prevention.ABSTRAKLatar belakang: Prevalensi obesitas pada semua kelompok umur meningkat di hampir seluruh negara di dunia. Studi epidemiologi menunjukkan bahwa asupan energi dan zat gizi makro diakhir pekan meningkat dibandingkan hari biasa dan berperan pada kejadian obesitas.Tujuan: Tujuan dari literatur review ini adalah untuk menganalisis perbedaan asupan energi dan zat gizi makro diakhir pekan dibandingkan hari biasa dan bagaimana kontribusinya terhadap obesitas.Metode: Metode yang digunakan adalah metode penelusuran artikel  jurnal internasional yang ditelusuri menggunakan electronic database seperti medline NCBI (National Center for Biotechnology Information), embase, dan penelusuran dengan google schoolar.Hasil: Hasil telaah beberapa artikel menunjukan bahwa rata-rata asupan energi dan zat gizi makro mengalami peningkatan saat akhir pekan dibandingkan hari biasa. Konsumsi unhealthy food di akhir pekan seperti makanan dan minuman dengan kandungan tinggi gula, tinggi lemak, dan alkohol tampaknya menyebabkan peningkatan kalori dan berperan pada insiden obesitas.Kesimpulan: Diperlukan upaya pencegahan obesitas melalui promosi kesehatan masyarakat dengan memperhatikan asupan makanan saat hari libur baik dari segi kuantitas maupun kualitasnya.

Peran Asam Amino Sitrulin dalam Meningkatkan Performa Olahraga Pada Atlet

Background: Citrulline is an ergogenic non-essential amino acid which is able to increase production, efficiency, and use of energy, as well as performance in sport. Purpose: The objective of this literature review was to explain the role of citrulline in improving exercise performance through both aerobic and anaerobic metabolic pathways. Discussion: The results showed evidence that citrulline has role in improving exercise performance. Several articles indicate that the consumption of citrulline either supplement or watermelon given during certain period or acute before the test might increase VO2max, retard muscle fatigue, and decrease delayed onset muscle soreness. Some studies used 6-8 g citrulline before exercise, but lower dose was used in some other studies. Conclusion: Amino acids citrulline either supplement or watermelon is believed to have role in improving exercise performance in athletes although there is no recommendation dose has been found. ABSTRAKLatar Belakang: Sitrulin merupakan asam amino non esensial yang bersifat ergogenik yaitu dapat meningkatkan produksi, efisiensi, dan penggunaan energi serta performa olahraga.Tujuan: Tujuan penulisan kajian pustaka ini adalah untuk menjabarkan peran sitrulin dalam meningkatkan performa olahraga melalui jalur metabolisme baik aerobik maupun anaerobik.Ulasan: Hasil literature review menunjukkan bukti bahwa sitrulin memiliki peran dalam meningkatkan performa olahraga atlet. Beberapa artikel menunjukkan bahwa konsumsi sitrulin baik dalam bentuk suplemen maupun buah semangka yang diberikan selama jangka waktu tertentu maupun sesaat sebelum dilakukan tes latihan fisik mampu meningkatkan VO2max, menunda kelelahan otot, dan mengurangi rasa nyeri otot pasca latihan. Beberapa penelitian menggunakan dosis 6-8 g sitrulin sebelum olahraga, beberapa penelitian lain menggunakan dosis yang lebih rendah.Kesimpulan: Asam amino sitrulin baik dalam bentuk suplemen maupun buah semangka diyakini memiliki peran dalam meningkatkan performa olahraga atlet walaupun rekomendasi dosis baku yang disarankan belum ditemukan.

Citrulline malate supplementation does not improve German Volume Training performance or reduce muscle soreness in moderately trained males and females

BACKGROUND

Use of supplements to aid performance is common practice amongst recreationally active individuals, including those without a sufficient evidence base. This investigation sought to assess whether acute supplementation with 8 g of citrulline malate (CM) (1.11: 1 ratio) would improve anaerobic performance.

METHODS

A randomised double blind placebo control trial was employed, using a counterbalanced design. We recruited recreationally active men and women to take part in an isokinetic chair protocol, based on German Volume Training (GVT) whereby participants attempted to perform 10 sets of 10 repetitions against a force representing 70% of their peak concentric force.

RESULTS

The number of repetitions achieved over the course of the GVT was 94.0 ± 7.9 and 90.9 ± 13.9 for placebo and CM respectively. There was no significant difference between the placebo and CM treatment for number of repetitions (P = 0.33), isometric (P = 0.60), concentric (P = 0.38), or eccentric (P = 0.65) peak force following the GVT. Total muscle soreness was significantly higher in the CM compared to the placebo treatment following the GVT protocol over 72 h (P = 0.01); although this was not accompanied by a greater workload/number of repetitions in the CM group.

CONCLUSIONS

We conclude that an acute dose of CM does not significantly affect anaerobic performance using an isokinetic chair in recreational active participants. Practical implications include precaution in recommending CM supplementation. Coaches and athletes should be aware of the disparity between the chemical analyses of the products reviewed in the present investigation versus the manufacturers' claims.