L-Arginine
Research reviewed: To review
L-Arginine is a dietary supplement with 17 published peer-reviewed studies involving 410 participants, researched for General.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
General
StrongResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
General
To evaluate the safety, tolerability, and effects of L-arginine-ketoglutarate on exercise performance in trained adult men
Study Type
Randomised, double-blind, placebo-controlled design
Purpose
To evaluate the safety, tolerability, and effects of L-arginine-ketoglutarate on exercise performance in trained adult men
Dose
12 g/day of L-arginine alpha-ketoglutarate (3 x 4 g caplets) or placebo
Participants
Study 1: 10 healthy male subjects with an average age of 37 years old Study 2: 35 experienced, resistance-trained males with an average age of 39 years
Duration
8 weeks
Results
The analysis of the 1RM bench press over 8 weeks showed a significant difference between groups (Arginine: 8.82 kg versus Placebo: 2.67 kg). However, no significant differences were observed between the arginine and placebo groups in isokinetic right quadriceps muscle endurance variables: peak torque, time to peak torque, total work, and work fatigue. In addition, no significant changes were observed in body composition or aerobic capacity between the arginine and placebo groups.
To evaluate the safety, tolerability, and effects of L-arginine-ketoglutarate on exercise performance in trained adult men
Study Type
Randomised, double-blind, placebo-controlled design
Purpose
To evaluate the safety, tolerability, and effects of L-arginine-ketoglutarate on exercise performance in trained adult men
Dose
12 g/day of L-arginine alpha-ketoglutarate (3 x 4 g caplets) or placebo
Participants
Study 1: 10 healthy male subjects with an average age of 37 years old Study 2: 35 experienced, resistance-trained males with an average age of 39 years
Duration
8 weeks
Results
Over 8 weeks, the researchers observed that the group taking arginine significantly increased their 1RM bench press by 8.82 kg, compared to just 2.67 kg in the placebo group. However, there were no significant differences between the arginine and placebo groups in muscle endurance of the right quadriceps, body composition, or aerobic capacity.
To investigate the effects of L-arginine supplementation on sport performance and body composition in male soccer players.
Study Type
Randomised controlled trial
Purpose
To investigate the effects of L-arginine supplementation on sport performance and body composition in male soccer players.
Dose
2 g/day L-arginine or placebo
Participants
56 male soccer players with an average age of 21 years
Duration
45 days
Results
The researchers observed that L-arginine supplementation at 2 g per day for 45 days significantly increased sport performance (VO2 max) in male athletes compared to placebo. VO2 max, or maximal oxygen uptake, is a measure of the maximum amount of oxygen an athlete can use during intense exercise. It is a common indicator of cardiovascular fitness and aerobic endurance. An increase in VO2 max suggests that the athletes' bodies were better able to utilise oxygen during physical activity, which likely contributed to improved athletic performance. On the other hand, L-arginine supplementation did not have a significant effect on anthropometric measurements like BMI, BFM, and LBM in male soccer players.
To investigate the effects of L-arginine supplementation on sport performance and body composition in male soccer players.
Study Type
Randomised controlled trial
Purpose
To investigate the effects of L-arginine supplementation on sport performance and body composition in male soccer players.
Dose
2 g/day L-arginine or placebo
Participants
56 male soccer players with an average age of 21 years
Duration
45 days
Results
The researchers observed that L-arginine supplementation at 2 g per day for 45 days significantly increased maximal oxygen uptake (VO2 max) in male athletes compared to placebo. VO2 max, or maximal oxygen uptake, is a common indicator of cardiovascular fitness and aerobic endurance. An increase in VO2 max suggests that the athletes' bodies were better able to utilise oxygen during physical activity, which likely contributed to improved athletic performance.
To investigate the effects of acute L-arginine ingestion on nitric oxide synthesis and the physiological responses to low- and high-intensity exercise in healthy men
Study Type
Randomised, placebo-controlled, clinical trial
Purpose
To investigate the effects of acute L-arginine ingestion on nitric oxide synthesis and the physiological responses to low- and high-intensity exercise in healthy men
Dose
6 g/day of l-arginine in a 500 ml beverage or placebo
Participants
9 healthy men aged 19-38 years.
Duration
3 days
Results
The researchers observed that L-arginine supplementation significantly enhanced exercise efficiency and tolerance. This was evidenced by a reduction in the oxygen cost of moderate-intensity exercise, meaning that the muscles required less oxygen to perform the same amount of work, making the exercise feel easier and more sustainable. Additionally, The researchers also observed that L-arginine significantly blunted the oxygen consumption during severe-intensity exercise. Typically, during high-intensity exercise, oxygen consumption gradually increases, leading to rapid fatigue. However, L-arginine helped mitigate this rise, allowing individuals to maintain higher performance levels for longer periods without tiring quickly. Furthermore, the study found a significant association between L-arginine supplementation and extended the time to exhaustion, enabling individuals to exercise for longer durations before reaching the point of complete fatigue. These benefits are primarily attributed to L-arginine’s role in increasing nitric oxide production, which enhances blood flow, reduces overall oxygen consumption, and improves muscle function, making it a valuable supplement for boosting exercise performance and endurance.
To investigate the effects of short-term L-arginine ingestion on nitric oxide synthesis and the physiological responses to low- and high-intensity exercise in healthy men
Study Type
Randomised, placebo-controlled, clinical trial
Purpose
To investigate the effects of short-term L-arginine ingestion on nitric oxide synthesis and the physiological responses to low- and high-intensity exercise in healthy men
Dose
6 g/day of l-arginine in a 500 ml beverage or placebo
Participants
9 healthy men aged 19-38 years.
Duration
3 days
Results
The study found an association between L-arginine supplementation and significantly improved exercise efficiency and tolerance. This was shown by a significant reduction in the oxygen needed for moderate-intensity exercise, making it feel easier and more sustainable. Additionally, the participants in the l-arginine group demonstrated reduced oxygen consumption during intense exercise, allowing individuals to maintain higher performance levels for longer without getting tired quickly. The researchers also observed a significant increase in the time to exhaustion, meaning individuals could exercise longer before becoming completely fatigued. These benefits are mainly due to L-arginine increasing nitric oxide production, which improves blood flow, reduces overall oxygen use, and enhances muscle function, making it a valuable supplement for boosting exercise performance and endurance.
To investigate the acute effects of an arginine-based supplement on delaying neuromuscular fatigue in untrained individuals.
Study Type
Randomised, placebo-controlled, clinical trial
Purpose
To investigate the acute effects of an arginine-based supplement on delaying neuromuscular fatigue in untrained individuals.
Dose
A single dose of a supplement containing 3.0 g of arginine, 300 mg of grape seed extract, and 300 mg of polyethylene glycol or placebo
Participants
19 untrained men with an average age of 22 years
Duration
Single dose
Results
The researchers observed significant improvements in the ventilatory threshold and delayed neuromuscular fatigue in untrained individuals taking the arginine supplement. However, the supplement did not significantly affect lactate threshold, peak oxygen uptake, or time to exhaustion.
To investigate the effects of a single-dose arginine-based supplement on delaying neuromuscular fatigue in untrained individuals.
Study Type
Randomised, placebo-controlled, clinical trial
Purpose
To investigate the effects of a single-dose arginine-based supplement on delaying neuromuscular fatigue in untrained individuals.
Dose
A single dose of a supplement containing 3.0 g of arginine, 300 mg of grape seed extract, and 300 mg of polyethylene glycol or placebo
Participants
19 untrained men with an average age of 22 years
Duration
Single dose
Results
The researchers observed that untrained individuals taking the arginine supplementation showed significant improvements in breathing efficiency and delayed muscle fatigue. However, the supplement did not significantly improve their lactate threshold, peak oxygen uptake, or the amount of time they could exercise before getting exhausted.
To investigate the effects of L-arginine supplementation on muscle performance during resistance exercise in healthy individuals
Study Type
Randomised controlled trial
Purpose
To investigate the effects of L-arginine supplementation on muscle performance during resistance exercise in healthy individuals
Dose
6 g of L-arginine orally in encapsulated form with 400 mL of water or placebo
Participants
15 healthy male participants with an average age of 26 years
Duration
Single-dose
Results
The researchers observed that oral supplementation with a single dose of L-arginine significantly increased blood flow to muscles during the recovery period between sets of resistance exercise, without significantly changing muscle oxygen levels, as measured by Near-Infrared Spectroscopy (NIRS). This means that taking L-arginine helped to improve the circulation of blood to the muscles after exercise, which could potentially aid in muscle recovery and nutrient delivery. However, the lack of significant change in muscle oxygenation suggests that L-arginine did not affect how much oxygen the muscles were using or receiving during recovery. Despite these changes in blood flow, the study found no significant differences in nitric oxide levels (NOx) or in elbow flexion strength performance between the groups. Nitric oxide is a molecule that helps to relax blood vessels and improve blood flow, but in this study, L-arginine did not significantly alter its levels. Additionally, key measures of muscle strength performance—such as peak torque (the maximum rotational force produced by the elbow flexors), total work (the total amount of work done during the exercise), and set total work (the work done per set)—were not significantly different between those who took L-arginine and those who did not. Overall, the results suggest that L-arginine supplementation increased muscle blood volume during recovery from resistance exercise but did not improve muscle oxygenation or strength performance.
To investigate the effects of L-arginine supplementation on muscle performance during resistance exercise in healthy individuals.
Study Type
Randomised controlled trial
Purpose
To investigate the effects of L-arginine supplementation on muscle performance during resistance exercise in healthy individuals.
Dose
6 g of L-arginine orally in encapsulated form with 400 mL of water or placebo
Participants
15 healthy male participants with an average age of 26 years
Duration
Single-dose
Results
The researchers observed that taking a single dose of L-arginine significantly increased blood flow to muscles during recovery after resistance exercise, potentially helping with muscle recovery and nutrient delivery. However, it did not change muscle oxygen levels, meaning it didn't affect how much oxygen the muscles were using or getting during recovery. Despite the improved blood flow, there were no significant changes in nitric oxide levels or muscle strength performance between those who took L-arginine and those who didn't. Measures like peak torque, total work, and set total work remained the same. Overall, the results suggest that L-arginine may help increase blood flow to muscles after exercise but may not improve muscle oxygenation or strength.
To investigate the impact of L-arginine supplementation on small blood vessels, which play an important role in overall cardiovascular health and athletic performance, in young trained individuals.
Study Type
Clinical trial (uncontrolled)
Purpose
To investigate the impact of L-arginine supplementation on small blood vessels, which play an important role in overall cardiovascular health and athletic performance, in young trained individuals.
Dose
0.9 g of L-arginine (single dose)
Participants
51 healthy male volunteers aged 20-74 years
Duration
Single dose
Results
The researchers observed that a single-dose of L-arginine supplementation significantly improved endothelium-dependent vasodilation predominantly in young, trained individuals, however it did not have a significant effect on medium-aged subjects. Vasodilation is crucial for proper blood flow and overall cardiovascular health. The inner lining of the blood vessels, called the endothelium, plays a key role in this process. When the endothelium functions well, it helps the blood vessels to relax and widen, allowing more blood to flow through. The nonsignificant effect observed in middle-aged men may be due to age-related changes in the cardiovascular system, where the blood vessels and endothelium might not respond as effectively to the supplement.
To investigate the impact of L-arginine supplementation on small blood vessels, which are crucial for heart health and athletic performance, in young, trained individuals.
Study Type
Clinical trial (uncontrolled)
Purpose
To investigate the impact of L-arginine supplementation on small blood vessels, which are crucial for heart health and athletic performance, in young, trained individuals.
Dose
0.9 g of L-arginine (single dose)
Participants
51 healthy male volunteers aged 20-74 years
Duration
Single dose
Results
The researchers observed that a single dose of L-arginine significantly improved blood vessel function in young, trained individuals by enhancing vasodilation, which is important for good blood flow and heart health. However, it did not have a significant effect on middle-aged subjects. This may be because ageing causes changes in the cardiovascular system, making the blood vessels and endothelium less responsive to the supplement.
To investigate effects of chronic supplementation of L-Arginine on physical fitness in water polo players.
Study Type
Randomised, placebo-controlled, clinical trial
Purpose
To investigate effects of chronic supplementation of L-Arginine on physical fitness in water polo players.
Dose
5 g/day of L-Arginine or placebo
Participants
17 male professional water polo players with an average age of 30 years
Duration
4 weeks
Results
The study observed an association between L-Arginine supplementation and improved oxygen use in the body during exercise, shown by a lower lactate-to-speed ratio. This means that with L-Arginine, muscles produce less lactic acid for the same running speed, reducing fatigue and allowing for better performance compared to those who didn't take the supplement.
To explore the effects of arginine in combination with other antioxidants on performance in elderly male cyclists
Study Type
Randomised, double-blind, placebo-controlled, clinical trial
Purpose
To explore the effects of arginine in combination with other antioxidants on performance in elderly male cyclists
Dose
5.2 g L-arginine in a proprietary blend with L-citrulline, 500 mg ascorbic acid, 400IU vitamin E, 400 μg folic acid, 300 mg L-taurine, and 10 mg alpha lipoic acid in a lemon-flavoured powder form or placebo
Participants
16 male cyclists
Duration
3 weeks
Results
The study observed an association between L-Arginine supplementation and improved performance in terms of anaerobic threshold and power output. The anaerobic threshold, the point where muscles start to tire from lactic acid, increased by 16.7% in the first week and 14.2% in the third week for the supplement group, with no change in the control group. Improving your anaerobic threshold means you can exercise harder and longer before reaching this point of fatigue. Additionally, the power output at this threshold, indicating muscle strength and efficiency, increased by 22.51 watts in the first week and 20.66 watts in the third week for the supplement group, while the control group showed no significant change.
To investigate the effects of short-term oral supplementation of L-arginine on blood pressure and exercise capacity in patients with precapillary pulmonary hypertension
Study Type
Randomised, double-blind, placebo-controlled, clinical trial
Purpose
To investigate the effects of short-term oral supplementation of L-arginine on blood pressure and exercise capacity in patients with precapillary pulmonary hypertension
Dose
1.5-g capsule/10 kg body weight (3 x 0.5 g/10 kg body weight capsules) or placebo
Participants
19 male and female patients with precapillary pulmonary hypertension with an average age of 49 years
Duration
1 week treatment
Results
The study found an association between oral L-Arginine supplement and significant increase in a marker that improves blood flow. The researchers observed a 9% decrease in lung artery pressure and a 16% decrease in lung blood vessel resistance. It also slightly lowered overall blood pressure and increased the maximum oxygen the body could use. These significant improvements suggest that L-Arginine may help heart and lung function and exercise ability in patients with high blood pressure in the lungs. No changes were seen with the placebo.
To investigate the short-term effects of L-arginine on hormonal and metabolic responses during in trained cyclists
Study Type
Randomised, double-blind, placebo-controlled, clinical trial
Purpose
To investigate the short-term effects of L-arginine on hormonal and metabolic responses during in trained cyclists
Dose
Approximately 5.8 grams of L-arginine or placebo
Participants
15 aerobically trained men with an average age of 28 years
Duration
Single dose
Results
The researchers observed that taking L-Arginine significantly increased its levels in the blood by about 146%, compared to no change with a placebo. This suggests that the body is absorbing and utilising the supplement effectively. Additionally, the researchers observed that those who took L-Arginine demonstrated reduced fat burning at the start of exercise and slightly increased glycerol (a marker of fat breakdown) at 45 minutes.
To examine the effects of taking an arginine-based supplement daily for 4 weeks on gas exchange threshold (the point where breathing increases during exercise) and peak oxygen uptake ( the highest amount of oxygen used during intense exercise).
Study Type
Randomised, double-blind, placebo-controlled, clinical trial
Purpose
To examine the effects of taking an arginine-based supplement daily for 4 weeks on gas exchange threshold (the point where breathing increases during exercise) and peak oxygen uptake ( the highest amount of oxygen used during intense exercise).
Dose
3.0 g of arginine (in combination with 300 mg of grape seed extract, and 300 mg of polyethylene glycol) or placebo
Participants
41 males with an average age of 22 years
Duration
4 weeks
Results
The researchers observed that participants who took L-Arginine showed significant improvements: a 4.1% increase in the gas exchange threshold ((the point where breathing increases during exercise), a 4.3% increase in carbon dioxide output (a measure of how well your body is processing energy), and a 5.4% increase in power output (how strong you are). The placebo group did not show significant improvements in these areas. Overall, the results suggest that L-Arginine may help improve exercise performance and efficiency.
Frequently Asked Questions
Common questions about L-Arginine research
There are currently 17 peer-reviewed studies on L-Arginine, involving 410 total participants. Research covers General. The overall evidence strength is rated as Strong.
The evidence is currently rated as "Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (17 human studies), and reported outcomes.
L-Arginine has been researched for: General. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 17 out of 17 studies are human trials. Human trials carry more weight in our evidence scoring system.
