THE OVRL QUALITY STANDARD
A Performance Ingredient Should Be Judged by Its Dose — Not Simply by Its Presence
At OVRL, we believe that seeing an ingredient on a pre-workout label is not enough to determine whether a formula meaningfully reflects the scientific research behind that ingredient.
For citrulline malate, dose matters, the citrulline-to-malate ratio matters, supplement quality matters, and the type of exercise being performed matters.
Citrulline malate is frequently included in pre-workout formulas because of its proposed relationship with nitric oxide production, blood flow, energy metabolism and resistance to fatigue. However, the available research does not show that every dose produces the same effect, nor that positive outcomes are universal across exercises or populations.
The 2026 study by Lewis A. Gough and colleagues is especially relevant because it directly compared two different acute doses of citrulline malate — 8 g and 12 g — against placebo in trained individuals.
The results reinforce an important principle of the OVRL Quality Standard:
the presence of citrulline malate creates a scientific rationale, but the dose and composition determine how closely a finished formula corresponds to the protocols actually studied.
WHAT THE RESEARCH SHOWS
“Citrulline malate (CM) is an inorganic salt synthesised from the non-essential amino acid L-citrulline and the tricarboxylic cycle intermediate malate. As a precursor for L-arginine, L-citrulline ingestion can augment the synthesis of nitric oxide, a key signalling molecule that facilitates vasodilation [1]. Combined L-citrulline and malate consumption has also been shown to increase blood flow to skeletal muscle, which has been largely evidenced by a reduction in post-exercise systolic and diastolic blood pressure [2]. Malate may also have additional mechanisms including increasing the rate of oxidative ATP production and phosphocreatine re-synthesis [3]. Furthermore, the addition of malate may increase the elimination of ammonia produced during high-intensity exercise, as inferred by high post-exercise lactate, and increase tricarboxylic cycle efficiency via enhancement of the malate aspartate shuttle (MAS) [4]. Based on these mechanisms, CM ingestion is potentially well suited to resistance exercise performance on the premise that these mechanisms would lead to increased training output, and this could increase the potential strength and/or power improvements from training. Positive findings have been reported following acute CM ingestion with the commonly employed dose of 8 g when consumed 30–60 min prior to exercise [5,6,7]. These collection of studies have reported improvements in the number of repetitions performed to failure, a reduced rate of perceived exertion and/or delayed-onset muscle soreness. For example, Pérez-Guisado and Jakeman (2010) [5] reported total reps during four sets to failure (at 80% 1RM) were improved significantly following ingestion of 8 g CM. Unfortunately, out of the studies reporting benefits only Wax et al. (2015) [6] reported post-exercise lactate and this was unchanged, which makes it difficult to draw conclusions on the acting mechanism. They also reported no significant difference in post-exercise blood pressure, which would allude to a non-blood flow mechanism. Moreover, these effects are not universal across studies, with many reporting no effects of CM ingestion on resistance exercise protocols [8,9,10]. Reasons for these discrepancies could have been the known issues with supplement quality, where the citrulline:malate ratio in the CM administered to participants via independent testing was much lower than purported by the manufacturer (manufacturers claims: 2:1 vs. independent testing: 1.1:1) [8,9]. Equally, there is variation in the methodologies across studies, including the percentage RM used in the studies, exercise selection, and participant training status.”
“The linear mixed-effect model found no significant differences in the completed repetitions between exercise type but did reveal a significant main effect of CM-HIGH on repetitions completed (p = 0.032), which was not found for CM-MOD. However, post hoc testing was unable to find a significant difference in repetitions between CM-HIGH and CM-MOD or placebo (20, 18, and 17 repetitions respectively). However, exploratory analyses indicate a possible interaction between CM dosage and exercise type. Although not significant, estimated marginal means show an increase in leg press repetitions from 17 at placebo to 19 at CM-MOD and 20 at CM-HIGH, whereas repetitions in the row exercise remain consistent across dosages (EMMs were within 0.4 repetitions). Mean pre- and post-exercise blood lactate responses for leg press and bent-over row are displayed in Figure 4 and Figure 5, respectively. Lactate significantly increased at the Middle and Post RT (p = 0.003 and p < 0.001, respectively). There were no significant effects of citrulline malate for lactate or heart rate. Time had no significant effect on diastolic blood pressure. CM-MOD reduced diastolic blood pressure (p = 0.049), though significance was not achieved with CM-HIGH (p = 0.099). The results of this study show that CM-HIGH may improve total leg press repetitions, whereas CM-MOD and placebo revealed no significant effects. For barbell bent-over rows, no significant effects were reported following ingestion of either CM dose. The findings of this study may therefore support the use of CM-HIGH for improving total repetitions during resistance exercise performance, specifically during leg press activity. CM-HIGH improved the total number of repetitions of leg press and CM-MOD was not ergogenic for either exercise, and these findings with the latter dose of CM agree with other studies that found no effects of CM ingestion on resistance exercise performance.”
THE STUDY
8 g vs. 12 g vs. Placebo in Trained Individuals
This was a double-blind randomized controlled pilot trial designed to compare a moderate and higher acute dose of citrulline malate.
The study involved:
12 trained adults
Three experimental conditions were compared:
CM-MOD — 8 g citrulline malate
CM-HIGH — 12 g citrulline malate
Placebo
The resistance exercise protocol included:
Leg press
and:
Barbell bent-over row
Participants completed resistance exercise at approximately:
70% of 1RM
with the final set performed to exhaustion.
The researchers evaluated outcomes including:
- number of repetitions completed;
- exercise-specific performance;
- blood lactate;
- heart rate;
- systolic and diastolic blood pressure.
This design allowed the researchers to ask not only whether citrulline malate influenced performance, but also whether a higher dose behaved differently from a commonly used moderate dose.
KEY FINDINGS
1. The Higher Dose Produced a Significant Main Effect
The statistical model found a significant main effect for:
CM-HIGH — 12 g
on repetitions completed.
p = 0.032
The same main effect was not observed with the 8 g dose.
This suggests a potential dose-dependent performance response.
However, an important statistical qualification follows.
2. Post Hoc Comparisons Were Not Significant
Despite the significant main effect for the high-dose condition, direct post hoc comparisons did not identify a statistically significant difference between:
12 g
8 g
and:
placebo
The reported repetition values were approximately:
12 g CM — 20 repetitions
8 g CM — 18 repetitions
Placebo — 17 repetitions
This distinction is important.
It would therefore be too strong to say that the study definitively proved that 12 g significantly outperformed placebo in all pairwise analyses.
The authors themselves use cautious language, stating that the higher dose “may improve” performance.
EXERCISE-SPECIFIC RESPONSE
The Performance Signal Appeared in Leg Press — Not Bent-Over Row
Exploratory analysis suggested a possible interaction between:
citrulline malate dose
and:
exercise type.
For the leg press, estimated repetitions increased progressively:
Placebo — approximately 17
8 g — approximately 19
12 g — approximately 20
By contrast, repetitions during the barbell bent-over row remained almost unchanged across conditions.
The estimated marginal means differed by only approximately:
0.4 repetitions
between doses.
This is one of the most important findings of the paper because it suggests that any ergogenic effect of citrulline malate may not be equally expressed across all forms of resistance exercise.
THE 8 g DOSE
The Commonly Used “Moderate” Dose Was Not Ergogenic in This Protocol
The 8 g dose is particularly relevant because it has been frequently used in previous citrulline malate research.
Earlier studies cited by the authors had reported improvements in outcomes such as:
- repetitions to failure;
- perceived exertion;
- delayed-onset muscle soreness.
However, in this particular experiment:
8 g did not significantly improve resistance exercise performance.
The authors state that the moderate dose was:
“not ergogenic for either exercise.”
This does not prove that 8 g is ineffective in every training context.
Rather, it reinforces the variability already present in the wider literature.
The effect may depend on:
- exercise selection;
- training status;
- total volume;
- intensity;
- supplement quality;
- dose;
- and actual citrulline concentration.
THE 12 g DOSE
A Higher Dose May Be Required Under Certain Resistance-Exercise Conditions
The study's high-dose condition used:
12 g citrulline malate
The authors report that this dose may improve total repetitions, particularly for leg press performance.
The finding raises the possibility that a larger acute dose may be required to produce an observable effect under certain resistance-training conditions.
However, this should not be generalized into:
“12 g is the optimal dose for everyone.”
The study was a pilot trial involving only 12 trained adults, the effect was exercise-specific, and post hoc comparisons did not produce a statistically significant difference between the individual conditions.
The result is therefore best understood as a performance signal requiring confirmation, rather than a universal dosing rule.
BLOOD LACTATE
Performance Changes Were Not Explained by a Citrulline-Induced Change in Lactate
Blood lactate increased significantly during and after resistance exercise, as expected.
The paper reports:
Middle of resistance training — p = 0.003
Post resistance training — p < 0.001
However:
citrulline malate had no significant effect on blood lactate.
This is relevant because one proposed mechanism for citrulline malate is improved handling of metabolites associated with high-intensity exercise.
In this protocol, the performance signal seen with the higher dose could not be clearly explained through a change in lactate response.
HEART RATE
No Significant Citrulline Malate Effect on Heart Rate
The researchers found:
no significant effect of citrulline malate on heart rate.
This further suggests that the potential performance effect observed with the higher dose was not accompanied by a measurable change in this cardiovascular variable.
BLOOD PRESSURE
The Moderate Dose Reduced Diastolic Blood Pressure — the Higher Dose Did Not Reach Significance
Interestingly, the 8 g condition produced a statistically significant reduction in:
diastolic blood pressure
with:
p = 0.049
The 12 g condition showed a trend but did not reach statistical significance:
p = 0.099
This is noteworthy because citrulline is often discussed in relation to nitric oxide and vasodilation.
However, the overall pattern does not provide a simple dose-dependent blood-pressure explanation for the performance findings.
The higher-performing dose was not the dose showing the statistically significant diastolic blood-pressure response.
MECHANISTIC CONTEXT
Citrulline May Influence More Than One Physiological Pathway
The authors discuss several potential mechanisms through which citrulline malate could theoretically influence exercise performance.
Nitric Oxide
L-citrulline is a precursor to L-arginine.
L-arginine can contribute to the production of:
nitric oxide
which plays an important role in:
vasodilation and blood-flow regulation.
Blood Flow
Combined citrulline and malate consumption has previously been associated with increased skeletal-muscle blood flow, often inferred through changes in post-exercise blood pressure.
However, the present study did not provide a straightforward blood-flow explanation for the observed performance signal.
ATP Production
The authors discuss malate's potential role in increasing:
oxidative ATP production
and:
phosphocreatine resynthesis.
Both processes are relevant to repeated high-intensity muscular contractions.
Ammonia Handling
Malate has also been proposed to help increase the elimination of ammonia produced during high-intensity exercise.
However, because lactate responses were not significantly altered by citrulline malate in this experiment, the present data do not establish this mechanism as the explanation for the performance findings.
Malate-Aspartate Shuttle
The authors also describe a potential contribution to tricarboxylic acid cycle efficiency through enhancement of the:
malate-aspartate shuttle.
Again, these are proposed physiological mechanisms and should not be treated as mechanisms directly demonstrated by this specific pilot trial.
SUPPLEMENT QUALITY
The Number on the Label May Not Always Reflect the Citrulline Actually Delivered
One of the most commercially relevant aspects of the paper is the discussion of supplement quality.
The authors describe previous research in which a citrulline malate supplement was marketed as having a:
2:1 citrulline-to-malate ratio
but independent analysis reportedly found approximately:
1.1:1.
That difference can substantially alter the amount of actual L-citrulline delivered by a fixed gram dose of “citrulline malate.”
For example, comparing two products that each list:
8 g citrulline malate
does not necessarily establish that they deliver the same quantity of L-citrulline if their ratios differ.
This reinforces another OVRL Quality Standard principle:
the declared total blend weight is only useful when the actual composition of that blend is known.
WHY THIS MATTERS
“6 g Citrulline Malate” Is Not the Same Thing as “6 g L-Citrulline”
This distinction is essential for consumers evaluating pre-workout formulas.
Citrulline malate combines:
L-citrulline
and:
malate.
Therefore, the gram amount printed for citrulline malate does not automatically represent the amount of pure L-citrulline being consumed.
The exact amount depends on the:
citrulline-to-malate ratio.
A 2:1 material and a 1:1 material can both be labeled as citrulline malate while delivering different amounts of L-citrulline in the same total serving weight.
Gough and colleagues specifically identify this as a possible explanation for inconsistencies in the scientific literature.
For OVRL, that makes dose transparency and raw-material specification particularly important.
HOW OVRL APPLIES THIS STANDARD
Explosive Power Provides 6 g of Citrulline Malate Per Serving — Below the Doses Tested Here
Based on the formulation information supplied for this article, OVRL Explosive Power provides:
6 g L-citrulline DL-malate per serving
The study by Gough and colleagues evaluated:
8 g — moderate dose
and:
12 g — high dose.
This means that a single serving of Explosive Power provides a lower total citrulline malate dose than either experimental condition in this particular study.
RESEARCH AT A GLANCE
Lead author: Lewis A. Gough
Institution: Birmingham City University
Laboratory: Research for Human Performance and Health Laboratory
Centre: Centre for Life and Sport Science
Publication: Journal of Functional Morphology and Kinesiology
Year: 2026
Article type: Double-blind randomized controlled pilot trial
Participants: 12 trained adults
Ingredient: Citrulline malate
Experimental doses:
8 g — moderate dose
12 g — high dose
PlaceboExercise protocol:
Leg press and barbell bent-over row resistance exerciseExercise intensity: Approximately 70% 1RM
Main performance outcome: Repetitions completed
CM-HIGH main effect: p = 0.032
Post hoc comparisons: No statistically significant pairwise difference between 12 g, 8 g and placebo
Approximate repetition values reported:
12 g — 20
8 g — 18
Placebo — 17Exercise showing the clearest performance signal: Leg press
Bent-over row: No significant performance effect
Blood lactate: No significant effect of citrulline malate
Heart rate: No significant effect of citrulline malate
Diastolic blood pressure: Significant reduction with 8 g (p = 0.049); 12 g did not reach significance (p = 0.099)
Important methodological issue highlighted: Citrulline-to-malate ratio and supplement quality may contribute to inconsistent findings across studies.
READ THE ORIGINAL RESEARCH
The Comparative Effect of Acute Moderate- and High-Dose Citrulline Malate on Resistance Exercise Performance in Trained Individuals: A Double-Blind Randomised Controlled Pilot Trial
Gough, L. A., Tan, R., Bailey, S. J., Perrin, C., Roberts, C. J., & Gibbons, F.
Journal of Functional Morphology and Kinesiology
2026
DOI: 10.3390/jfmk11010115
Licence: CC BY 4.0 — Open Access