HealthyReachSciNCT06938126
Effects of L-Arginine and Citrulline Malate Supplementation on Sport Performance in Physically Active Men
A study testing L-Arginine and Citrulline-Malate Supplementation in people with Healthy, run by Hungarian University of Sports Science at 1 site in Hungary.
Trial summary
In this randomized, double-blind, placebo-controlled trial we investigated the effects of combined L-arginine (Arg) and citrulline-malate (CM) supplementation on aerobic, anaerobic, and high-intensity interval training in healthy, physically active men. Read more about this study
- Who is it for?
- Ages 18 to 30 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Healthy
- What is being tested?
- L-Arginine and Citrulline-Malate Supplementation
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 46 participants
- Where
- 1 siteHungary
- Study dates
- 1 Oct 2023to 30 Sep 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 30 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- being healthy, physically active with no history of injuries or illnesses at the time of measurement or within the preceding six months
Who cannot join
- consumption of any dietary supplements in the last six months to avoid confounding effects
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Acute Effects of Combined Supplementation of L-Arginine and Citrulline Malate on Aerobic, Anaerobic, and CrossFit® Exercise Performance
In this randomized, double-blind, placebo-controlled trial we investigated the effects of combined L-arginine (Arg) and citrulline-malate (CM) supplementation on aerobic, anaerobic, and high-intensity interval training in healthy, physically active men. 46 healthy, physically active men were divided into three distinct exercise protocol groups: CrossFit group, the Wingate Anaerobic Test group, and the Harvard Step Test group. The CrossFit performance assessment involved the "Cindy" workout, a high-intensity protocol composed of bodyweight exercises organized in a set sequence: 5 pull-ups, 10 push-ups, and 15 squats. Participants were instructed to perform as many rounds as possible within 20 minutes. The Wingate Anaerobic test involved a 30-second all-out cycling test on a bike ergometer, while the Harvard Step Test The Harvard Step Test was conducted using a 51 cm high platform, with participants stepping at a rate of 30 steps per minute (one second up, one second down) for five minutes or until exhaustion. Each participant attended three separate laboratory sessions. The initial session served for familiarization with the test protocol to minimize learning effects. In the second and the third sessions, participants attended two measurement sessions, conducted in randomized order and under double-blind conditions, where they received either the dietary supplementation or a placebo. Each participant acted as their control, allowing for within-subject comparisons.
Read the detailed description
Consumption of dietary supplements is a common strategy among athletes aiming to optimize recovery after training or competitions and enhance athletic performance. Amino acids L-arginine (Arg) and L-citrulline (Cit) are two of the most widely used supplements in recent times. Their use as nutritional supplements or dietary supplements to improve health and athletic performance has increased dramatically, as both Arg and Cit are essential for the body's synthesis of nitric oxide (NO) and elimination of waste products such as lactate during physical activity. Because it functions as an endogenous precursor to Arg, the primary substrate of nitric oxide, Cit, a non-protein, non-essential amino acid, has attracted a lot of attention lately for its potential to improve exercise performance. Commonly, citrulline is consumed as citrulline malate (CM), which is a mixture of Cit and malic acid in ratios ranging from 1:1 to 2:1. The combined intake of Arg and CM could potentially enhance athletic performance more effectively than using either supplement alone. This synergistic benefit is attributed to Cit's role in synthesizing additional Arg, which in turn elevates NO production, enhancing blood flow and possibly reducing muscle fatigue. Supporting this hypothesis, mixed supplementation of Arg and CM was examined in a previous study and significant increases in both force exertion and fatigue resistance during a 10-minute high-intensity cycling test was found. However, while initial evidence suggests potential ergogenic benefits of combined Arg and CM supplementation, further research is needed to confirm these effects across various exercise modalities. The aim of this study was to investigate the acute effects of combined Arg and CM supplementation on anaerobic performance, aerobic performance, or both through high-intensity interval training (i.e. CrossFit) outcomes in healthy, physically active men. Based on existing research, it was hypothesized that the supplementation would enhance performance by achieving higher peak power in the anaerobic protocol and CrossFit in the CrossFit training protocol, where rapid energy production and resistance to fatigue are critical.
- Conditions
- Healthy
- Being tested
- L-Arginine and Citrulline-Malate Supplementation, Placebo consumption
- Keywords
- L-arginine, Citrulline-malate, Sport-performance, CrossFit
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
L-Arginine and Citrulline-Malate SupplementationDietary supplement
L-Arginine and Citrulline Malate supplementation was consumed as a liquid one single time to examine the acute effects on sport performance
Placebo consumptionDietary supplement
Consumption of placebo as a liquid
| Study group | Role | What they receive |
|---|---|---|
| Supplementation | Experimental | Supplementation of L-Arginine and Citrulline-malate as a liquid Receives: Dietary Supplement: L-Arginine and Citrulline-Malate Supplementation |
| Placebo | Placebo comparator | Consumption of a placebo liquid Receives: Dietary Supplement: Placebo consumption |
What is being measured
The primary outcome is the main question the study is designed to answer.
Mechanical Power
Maximal and mean mechanical power was assessed during the Wingate Anaerobic Test under both conditions (supplementation and placebo).
Measured: Day 1 and Day 2
Fitness Score
During the CrossFit exercise and the Harvard Step Test the primare measure of performance was a Fitness Score, which was calculated from the rounds completed for the CrossFit exercise and from the time duration and heart rate for the Harvard Step Test.
Measured: Day 1 and Day 2
Secondary outcomes (1)
Heart Rate
Maximal and mean heart rate was measured for all three exercise protolcols: The Wingate Anaerobic Test, The CrossFit Test, and the Harvard Step Test.
Measured: Day 1 and Day 2
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Apr 2025
- Study start1 Oct 2023
- Primary completion15 May 2024
- Study completion30 Sep 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for HealthyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Each participant acted as their control, allowing for within-subject comparisons. Each participant attended three separate laboratory sessions. Measurement sessions were conducted in randomized order and under double-blind conditions, where participants received either the dietary supplementation or a placebo.
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 46 participants (actual)
Sponsor and investigators
- Lead sponsor
- Hungarian University of Sports Science
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Leonidas Petridis, Hungarian University of Sports Science
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06938126
- Sponsor's protocol ID
- TE-KEB/22/2023
- Other IDs
- HungarianUSportsScience
- Acronym
- ReachSci
- Status last verified
- Apr 2025
- First submitted
- 7 Apr 2025
- Last updated
- 22 Apr 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: All individual data the are included in the study and support the statistical analysis
Study at a glance
From the registry record, last updated by the sponsor on 22 Apr 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Acute Effects of Combined Supplementation of L-Arginine and Citrulline Malate on Aerobic, Anaerobic, and CrossFit® Exercise Performance
- ClinicalTrials.gov ID
- NCT06938126
- Acronym / sponsor ID
- ReachSci / TE-KEB/22/2023
- Conditions
- Healthy
- Keywords
- L-arginine, Citrulline-malate, Sport-performance, CrossFit
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 46 participants (actual)
- Lead sponsor
- Hungarian University of Sports ScienceUniversity, hospital or other
- Study start
- 1 Oct 2023 (actual)
- Primary completion
- 15 May 2024 (actual)
- Study completion
- 30 Sep 2024 (actual)
- First posted
- 22 Apr 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
In this randomized, double-blind, placebo-controlled trial we investigated the effects of combined L-arginine (Arg) and citrulline-malate (CM) supplementation on aerobic, anaerobic, and high-intensity interval training in healthy, physically active men. 46 healthy, physically active men were divided into three distinct exercise protocol groups: CrossFit group, the Wingate Anaerobic Test group, and the Harvard Step Test group. The CrossFit performance assessment involved the "Cindy" workout, a high-intensity protocol composed of bodyweight exercises organized in a set sequence: 5 pull-ups, 10 push-ups, and 15 squats. Participants were instructed to perform as many rounds as possible within 20 minutes. The Wingate Anaerobic test involved a 30-second all-out cycling test on a bike ergometer, while the Harvard Step Test The Harvard Step Test was conducted using a 51 cm high platform, with participants stepping at a rate of 30 steps per minute (one second up, one second down) for five minutes or until exhaustion. Each participant attended three separate laboratory sessions. The initial session served for familiarization with the test protocol to minimize learning effects. In the second and the third sessions, participants attended two measurement sessions, conducted in randomized order and under double-blind conditions, where they received either the dietary supplementation or a placebo. Each participant acted as their control, allowing for within-subject comparisons.
Detailed description
Consumption of dietary supplements is a common strategy among athletes aiming to optimize recovery after training or competitions and enhance athletic performance. Amino acids L-arginine (Arg) and L-citrulline (Cit) are two of the most widely used supplements in recent times. Their use as nutritional supplements or dietary supplements to improve health and athletic performance has increased dramatically, as both Arg and Cit are essential for the body's synthesis of nitric oxide (NO) and elimination of waste products such as lactate during physical activity. Because it functions as an endogenous precursor to Arg, the primary substrate of nitric oxide, Cit, a non-protein, non-essential amino acid, has attracted a lot of attention lately for its potential to improve exercise performance. Commonly, citrulline is consumed as citrulline malate (CM), which is a mixture of Cit and malic acid in ratios ranging from 1:1 to 2:1. The combined intake of Arg and CM could potentially enhance athletic performance more effectively than using either supplement alone. This synergistic benefit is attributed to Cit's role in synthesizing additional Arg, which in turn elevates NO production, enhancing blood flow and possibly reducing muscle fatigue. Supporting this hypothesis, mixed supplementation of Arg and CM was examined in a previous study and significant increases in both force exertion and fatigue resistance during a 10-minute high-intensity cycling test was found. However, while initial evidence suggests potential ergogenic benefits of combined Arg and CM supplementation, further research is needed to confirm these effects across various exercise modalities. The aim of this study was to investigate the acute effects of combined Arg and CM supplementation on anaerobic performance, aerobic performance, or both through high-intensity interval training (i.e. CrossFit) outcomes in healthy, physically active men. Based on existing research, it was hypothesized that the supplementation would enhance performance by achieving higher peak power in the anaerobic protocol and CrossFit in the CrossFit training protocol, where rapid energy production and resistance to fatigue are critical.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
- Model description
- Each participant acted as their control, allowing for within-subject comparisons. Each participant attended three separate laboratory sessions. Measurement sessions were conducted in randomized order and under double-blind conditions, where participants received either the dietary supplementation or a placebo.
| Arm | Type | Receives |
|---|---|---|
| Supplementation | Experimental | Dietary Supplement: L-Arginine and Citrulline-Malate SupplementationSupplementation of L-Arginine and Citrulline-malate as a liquid |
| Placebo | Placebo comparator | Dietary Supplement: Placebo consumptionConsumption of a placebo liquid |
Who may qualify
- Ages
- 18 to 30 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (1 listed)
- being healthy, physically active with no history of injuries or illnesses at the time of measurement or within the preceding six months
Key exclusion criteria (1 listed)
- consumption of any dietary supplements in the last six months to avoid confounding effects
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| L-Arginine and Citrulline-Malate SupplementationL-Arginine and Citrulline Malate supplementation was consumed as a liquid one single time to examine the acute effects on sport performance | Dietary supplement | Supplementation |
| Placebo consumptionConsumption of placebo as a liquid | Dietary supplement | Placebo |
Primary outcome
Mechanical Power
Time frame: Day 1 and Day 2
Maximal and mean mechanical power was assessed during the Wingate Anaerobic Test under both conditions (supplementation and placebo).
Fitness Score
Time frame: Day 1 and Day 2
During the CrossFit exercise and the Harvard Step Test the primare measure of performance was a Fitness Score, which was calculated from the rounds completed for the CrossFit exercise and from the time duration and heart rate for the Harvard Step Test.
1 secondary outcome
Heart Rate
Time frame: Day 1 and Day 2
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Apr 2025.
- Home page of the University of Sports ScienceLink provided by the sponsor.
- Individual participant dataSharing planned: Yes. All individual data the are included in the study and support the statistical analysis
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing L-Arginine and Citrulline-Malate Supplementation in people with Healthy, run by Hungarian University of Sports Science at 1 site in Hungary.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 22 Apr 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Hungary. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Mechanical Power (time frame: Day 1 and Day 2). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Apr 2025.