L-Citrulline is most commonly found in watermelons, while malate gets its name from the Latin word for "apple. You can get L-citrulline naturally in your diet. The human body also manufactures it from another amino acid, l-ornithine, through the urea cycle, a biochemical process that helps the body rid itself of ammonia, a waste product of protein digestion.
Citrulline enters this cycle of nitrogen disposal to create more arginine, which helps generate greater volumes of nitric oxide. Consuming arginine directly isn't quite as effective due to enzyme activity in the gut neutralizing arginine before it can be put to good use. Citrulline malate supplements raise ornithine and arginine plasma content, which improves the ammonia recycling process and nitric oxide synthesis.
Citrulline malate can help delay muscle fatigue by promoting increased aerobic energy. The same study found a 20 percent increase in phosphocreatine recovery after exercise, indicating a greater oxidative ATP synthesis contributing to energy production. While these results were found in a small group of sedentary subjects, it's possible they may apply to elite athletes, as well.
Like fatigue, muscle soreness can interrupt a workout. It can also cause a lot of physical discomfort, especially in the day or two after a workout. Citrulline malate has been shown to reduce this post-workout muscle soreness. Citrulline malate has shown significant benefits in increasing strength through different mechanisms.
A meta-analysis published in Sports Medicine indicated improved strength outcomes across a wide range of studies. Subjects repeated the GVT protocol under both treatment conditions. Prior to the GVT exercise protocol, subjects rested for 10 min in a seated position.
Blood samples were obtained by way of finger prick using a lancet Accu-chek, Safe-T-Pro. A second blood sample was taken for lactate analysis within 1 min of the completion of the GVT protocol. Subjects were provided with either the treatment 8 g of Citrulline Malate 1. Both conditions were provided in a mixture of 70 ml of fruit cordial and ml of water by RJ, or AA, and were consumed within a 5 min under the supervision.
Drinks were prepared in advance by JG based on information provided by MB, all authors were blinded for the duration of the trial period. The dosages and timing of the drink provision were based on research, which show citrulline peak levels occur 1 h after administration [ 10 ]. Prior to the GVT, subjects were asked to recall all the food and drink they consumed in the past 24 h. Subjects were advised to refrain from starting any new dietary or supplement regimes for the duration of their involvement in the project and to consume similar foods the day before and prior to visiting the laboratory.
The contents of the 24 h recall were analysed using dietary analysis software Nutritics , Dublin, Ireland. All results are expressed as total grams and calories per kilogram of bodyweight. The ratio of citrulline to malate within the dietary supplement used in the trial was assessed using nuclear magnetic resonance NMR spectroscopy. The analysis was performed individually on each of the five supplement powders in a blinded protocol and each powder was analysed in triplicate. The integration values for the triplicate runs of all five supplements are available as supplemental additional files Additional file 1.
All possible comparisons of integral values between chemical environments in citrulline and those in malate were then performed. These results are summarised in as additional files Additional file 2. The mean nuclear ratios for each individual replicate were then compiled into overall mean and standard deviation values which represent the citrulline:malate molar ratio calculated from 8 individual data comparisons and three total experimental repeats. We analysed differences in means between lactate and total number of reps performed using a paired samples t-test.
Post Hoc test were performed using pairwise comparisons with Bonferroni adjustment. No side effects were reported and the supplement and placebo were well tolerated. The dietary intake from the h recall is presented in Table 2 , there was no significant difference for macronutrient or energy intake between treatment conditions. Mean alcohol intake over the two treatment conditions was negligible 0.
The mean number of repetitions performed by the placebo and CM group declined to 8. The mean number of total repetitions performed across the treatment conditions was For more detail on pairwise comparisons, see additional files Additional file 3. Error bars indicate standard error of the mean. Maximal isometric, concentric and eccentric force at baseline and following each treatment condition is presented in Table 3.
A total of 10 subjects completed the F max follow-up tests due to technical issues. Following the GVT protocol blood lactate increased to 4. The difference between pre and post GVT blood lactate concentrations was calculated. The effect of the GVT protocol on the sum of total muscle soreness is displayed in Fig. Muscle soreness increased immediately following the GVT protocol and peaked at 24 h post exercise before declining by 72 h period in both treatment groups.
Analysis of specific muscle site soreness indicated that the Vastus Medialis and the Vastus Lateralis sites had consistently higher soreness ratings throughout the trial compared with the Tensor Fasciae and Rectus Femoris. Site specific VAS scores are available as an additional file Additional file 5. A Post Hoc was performed using a pairwise comparison and Bonferroni adjustment. Error bars indicate standard error of the mean, h, hours. The ratio of citrulline to malate measured in formulas from different supplement companies with purported ratios is displayed in Table 4.
The acute dose of CM was administered one hour before resistance training and did not significantly affect the number of repetitions performed. This finding is contrary to similar studies, which found significant effects from CM of the same dose [ 18 , 19 , 22 ]. In the present investigation not only did the CM not attenuate the marker of muscle soreness, but was associated with greater soreness over the 72 h following exercise.
Moreover, CM supplementation had no effect on blood lactate concentrations following exercise. More recently, a trial using a lower dose 6 g versus 8 g in the present investigation did not find any significant difference in any dependent variables including number of repetitions, soreness, creatinine kinase levels and rating of perceived exertion [ 25 ].
The present investigation also included chemical analysis of the supplement used, which concluded that the ratio of citrulline to malate was not equivalent to the ratio stated by the manufacturer. Analysis suggests that the supplement contained just over half the manufacturers stated dose of citrulline.
Subsequent analysis of four additional commercially available CM products, with a purported ratio of citrulline to malate , shows that only one of these products had a value close to the ratio stated by the manufacturers. This is the first study, to our knowledge, to report the citrulline to malate ratio of a number of these supplements. Although no difference was found for the main outcome measure of repetitions, this design utilised an acute dose of CM and our data supports the findings of recent investigations of resistance training performance [ 25 , 26 , 27 ].
In each instance, a 6 to 8 g acute dose CM had no effect on the number of repetitions achieved when performing either upper or lower-body resistance exercises compared to a placebo. By way of comparison, our results are in contrast to other trials, which investigated the effects of 8 g of acutely administered CM on the number of repetitions achieved during both upper and lower body exercise challenges [ 17 , 18 , 22 ].
It is however worth pointing out that there are differences in the study design, subject populations and mode of delivery between the present investigation and previous trials. The present study and utilised a single-leg leg extension exercise, and although the subjects had some experience with weight training the lack of familiarisation with the isokinetic chair protocol may have influenced performance. We did accommodate for this however with our counterbalanced design to negate any potential training effect.
It is plausible that CM may be more effective in highly trained resistance trained populations. Differences between fixed range of motion single joint exercises and multi joint exercises employed in the different modalities may have also resulted in the differences between this study and previous trials findings.
Although most athletes will likely utilise free weight exercises in their training, the use of an isokinetic chair should be considered a strength for its ability to deliver a consistent resistance and standardisation across subjects.
Citrulline malate supplementation also had no effect on the loss of force production and similar results were noted by Martinez-Sanchez et al. The addition of pomegranate juice containing ellagitannins however did improve efficacy of the supplement [ 29 ]. In contrast, CM was effective in retaining muscle power measured by counter measure jump in runners following a marathon Martinez-Sanchez et al. The protocol effectively reduces the number of repetitions achieved across set and was effective at increasing lactate concentrations in both the placebo and CM group.
Citrulline malate however had no effect on lactate buffering when compared to a placebo which might explain the lack of difference in repetition performance between the placebo and CM group. We did not measure citrulline, arginine or NOS, following supplementation. However, previous investigations have demonstrated there is a dose response relationship between ingestion of CM and plasma citrulline, ornithine, arginine and glutamine 1 h after consumption [ 10 , 20 , 29 ].
L-arginine is the key substrate in NO synthesis and it has been suggested that CM may increase NO synthesis indirectly: and subsequently muscle waste-product clearance e. Previous trials have produced mixed results in response to CM on lactate acid.
It seems exercise modality may have a bearing on CMs ability to influence blood lactate concentrations. Martinez-Sanchez et al. While, Kiyici et al. In contrast Cunniffe et al. Likewise, a 6 g per day, 15 supplementation protocol of CM had no effect on muscle pH in patients suffering from fatigue following aerobic finger flexion exercise [ 2 ].
Furthermore, in trials similar to this one, Wax et al. While Martinez-Sanchez et al. Interestingly however Martinez-Sanchez et al. The eccentric component of exercise is thought to be a prominent factor in causing DOMS [ 31 ], despite employing a concentric only protocol, the GVT was effective in increasing muscle soreness following the intervention. The CM did not attenuate the muscle soreness and actually appeared to increase soreness. This lack of effect on muscle soreness is in agreement with other investigations [ 25 ], and in contrast to other investigations [ 17 , 29 ].
Muscle soreness was also significantly reduced following administration with citrulline infused watermelon drinks following both a half marathon [ 29 ] and repeated sprints on a cycloergonometer The fact that soreness was reduced following both aerobic and anaerobic exercise trials may make a case for CM being more effective in reducing soreness across modalities. The lack of soreness seen in this study is consistent with the fact we also found no difference in repetition performance, force loss, or lactate between the placebo and CM group.
Presumably greater muscle soreness would likely have been observed had more repetitions been achieved from either group, although CM is proposed to offset this soreness by increased ammonium and lactate clearance.
We however did not measure ammonium concentrations but did note a failure in CM to resist fatigue. Chemical analysis of the CM product used in the study suggested that the citrulline:malate composition ratio was lower than that claimed by the manufacturer. The present investigation therefore used a lower dose of citrulline than we had intended administering around 4.
The lack of significant findings may therefore reflect a lower dosing of CM by comparison to other investigations. Interestingly citrulline has been infused into watermelon in other trials [ 29 , 32 ] and appears to be more readily absorbed from a matrix of watermelon compared to a functional drink. Many manufacturers state the use of formulas and it is unclear how much citrulline was administered in other investigations as the CM ratios and chemical analysis is often unreported.
Further investigations should therefore explore the composition of the product being tested, as this may influence measurements and outcomes.
Citrulline has been purported for its performance enhancing effect, while malate has been cited to improve performance via being an intermediate in the citric acid cycle. It seems more likely that citrulline is the active ingredient as malic acid is utilised to allow the supplement to form a stable salt for storage and neutralise the basicity of the supplement.
This stability issue may be overcome by infusion into a watermelon matrix. Performance-enhancing effects have been found from using citrulline in isolation [ 14 ] and researchers may wish to concentrate on using pure citrulline, to avoid under dosed products. Finally, given a number of trials suggesting a positive effect of CM on anaerobic performance for e.
There were a number of limitations of the present investigation include no measure of CK or ammonia to accompany the data gathered on lactate and muscle soreness. The subjects who participated in the study were not a homogenous group, and subjects varied in their training experience and included both men and women not controlling for the impact of menstrual cycling; however all participants had at least six months regular resistance training experience and are likely customers for the supplement in question.
We also did not perform the experiment fasted, but subjects were instructed to consume the same breakfast on both occasions, however we did note no difference in 24 h dietary intake between laboratory visits and point out that exercisers are unlikely to perform in the fasted state.
We also did not control or audit dietary supplements other than asking subjects to not stop or begin supplement regimes throughout the trial the rationale for this is that stopping or starting a new supplement could either positively or negatively affect performance. Furthermore, the isokinetic chair induces an eccentric and concentric force which is not the same, for example, as a standard leg extension exercise performed in a commercial fitness facility; field studies with commonly used equipment and exercises are needed to help answer questions over the efficacy of CM.
Athletes and coaches should remain sceptical as to the efficacy of CM. Well, most pre-workout products are designed to ingest minutes before training, or during the warm-up. Citrulline malate takes about an hour to convert to arginine and then nitric oxide ; so taking it right before training may not deliver significant ergogenic assistance.
To get the full benefit of citrulline, you need to take it an hour before you start training. This means you will probably have to ingest the fully effective dose of citrulline malate about half an hour before you normally consume your pre-workout supplement. For this reason, citrulline is an awesome stand-alone product, and not something that you will get the most benefit from if it is pre-combined with other pre-workout ingredients. If you are looking to increase your training volume by delaying fatigue, reducing muscle soreness, increasing growth hormone production, boosting immune function, and improving aerobic and anaerobic endurance, then taking the time to schedule your citrulline malate ingestion before your other pre-workout ingredients is well worth the effort and planning.
Citrulline malate can be a very useful tool in your arsenal of performance and recovery enhancing instruments, but only if you are willing to use it the way science has shown it to be effective. There are quite a few ingredients out there that can be very helpful at increasing training volume or improving recovery, but that may not be convenient when it comes to the traditional timing of pre-workout nutrition.
There are plenty of pre-workout products that contain citrulline, though rarely at an effective dose. Even if the dosage is effective, the recommended timing of ingestion is rarely long enough before training to deliver maximal benefit. Outside of the correct dosing and timing, though, citrulline is very much a waste of time and money.
For more information about citrulline, check out this page at examine. View more nutrition articles for athletes. Kevin Kuhn , M. There are limiting factors and key differences in every athlete. Whether fibre type, ability to use the stretch-shortening cycle effectively or even anthropometry. Having the knowledge to use these differences to the benefit of the athlete is a skill that Joel highlights brilliantly in this book.
0コメント