So, you want to make gains? Well, when we are strolling the aisles of any supplement shop, the whole point is to find a magic powder or pill that will give us an extra leg up on our performance right?Let me introduce you to L-arginine!
What is L-arginine? L-arginine is a conditionally non-essential amino acid — meaning the body can produce it endogenously through metabolic processes. However, in instances such as sickness, pregnancy, and severe trauma this amino acid becomes essential. An essential amino acid must be consumed via diet or supplement because the body cannot produce it on its own.
See Chapter 13 of the NASM Nutrition Certification Course for more on supplements.
What is L-ARginine?
L-arginine is specifically involved in the synthesis and bioavailability of nitric oxide (NO), a very potent vasodilator. Vasodilators expand the diameter of blood vessels to allow for greater blood flow. L-citruline, which can be found in some pre-workout mixes, is a precursor for l-arginine.
Does L-Arginine Work?
In clinical studies, L-arginine was specifically looked at to treat cardiovascular complications. In several studies, individuals with hypertension experienced lowered blood pressure and type 2 diabetics had decreased blood sugars after L-arginine administration.
So, if clinical settings produced promising results for L-arginine supplementation, what benefits could it produce for a healthy, active population?
Vasodilators in sports are of specific interest due to their ability to increase blood flow, gas exchange, oxygen kinetics, and muscle contractions. In certain studies, arginine specifically has been seen to enhance resting growth hormone levels which help stimulate muscle growth; reduce post-exercise lactate and ammonia levels which contribute to faster recovery and improve performance on strength and anaerobic based activities since arginine is a major amino acid involved in creatine synthesis.
L-Argine for Endurance Sports
When putting L-arginine to the test in long-endurance, high-intensity/anaerobic, and strength-based events, what did the results show?
In aerobic-based events, acute supplementation of 6-10g/day for 7 days or less seemed to improve time to exhaustion and exercise capacity. In male wrestlers, an improvement in time to exhaustion was seen, but no difference was seen in mean lactate levels.
L-Arginine for Strength Gains
In more anaerobic and strength-based events, chronic ingestion of L-arginine for 45-56 days of either 2g/day and upwards of 12g/day seemed to show improvements in 1-RM tests and Vo2max intensity tests, but no improvements were seen in the maximum number of repetitions or sprint power.
What does this tell us? The results are extremely varied, and many factors seem to influence someone’s ability to reap benefits from this supplement. Due to this fact, much more research is still needed to fully understand the effects and benefits of dosing on L-arginine.
But here’s what we can safely extract from the studies that have been conducted thus far. Chronic ingestion of lower doses (~1.5-3g/day) seems to offer greater adaptation and benefits compared to acute ingestion. If consuming acute doses, it seems apparent that extremely high doses of 10-12g offer performance benefits. However, the effects seem to greatly vary based on how “trained” an individual is. In several studies, acute ingestion of 6g/day for 2 weeks or less did not show any significant improvement in sprint capacity or strength tests. Additionally, while nutrient timing studies are limited for L-arginine, it has been suggested that ingestion 30-90 minutes before exercise will be the most beneficial in improving exercise performance.
the Benefits of L-Arginine SUpplements
Does L-arginine offer additional benefits? If it’s an amino acid, does it contribute to muscle growth?
In traumatic instances such as severe burns, increased arginine supplementation is implemented to preserve lean body mass. However, in healthy individuals, the research does not show any promising results of L-arginine increasing muscle mass. Under normal conditions, the body can produce enough arginine to support muscle growth.
One study that compared muscle protein synthesis using a mixture of both non-essential and essential amino acids vs only essential amino acids (completely excluding arginine), found no differences in muscle protein synthesis. This tells us that arginine alone isn’t sufficient to create a true anabolic response. Due to its role in nitric oxide and creatine synthesis, it is safer to say L-arginine has a greater role in increasing performance capacity compared to skeletal muscle growth.
Are Their Side Effects to Taking L-ARginine?
Again, the results seem extremely varied and are dependent on the individual. One study showed that healthy, active individuals seemed to tolerate larger doses (spread over the day and/or consumed in a single bolus) better than individuals suffering from metabolic diseases. The most reported side effects when consuming a large bolus of L-arginine are gastrointestinal discomfort, diarrhea, vomiting, and severe bloating. Most reports show no adverse effects in doses of 3-6g/day.
When ingestion exceeded 9g/day in a single bolus, more reports of adverse side effects were observed. However, those effects seemed to be mitigated when the dosage was decreased and spread over the day.
Currently, the observed safe level for L-arginine administration is ~20g/day, but higher levels have also been tested with no reports of serious, adverse effects. L-arginine has also been studied in various populations ranging from athletes to infants and has been deemed safe and well-tolerated.
Can You Get L-Arginine Naturally, Or Should You Supplement?
So, if you want to experiment with L-arginine, can you get it naturally from foods or is it only available in a supplement?
Well as previously discussed, L-arginine is amino acid! Where do amino acids exist naturally? Yup, you guessed it… Protein! You can get plenty of L-arginine in your diet by consuming dairy products, fish, poultry, and eggs. and other meats. Vegetarian and vegan friends have no fear. L-arginine exists in many seeds, nuts, and soybeans as well!
If you’re still on the fence about including this supplement in your diet, let’s recap what we just discussed.
1. L-arginine is completely safe in doses of 2-20g/day. It seems that dosing in lower doses of 1.5-3g/day for greater than 4 weeks can potentially offer some increased performance benefits. If dosing shorter-term (7 days or less), doses greater than 9g/day are needed.
2. L-arginine plays an essential role in nitric oxide synthesis. It seems to increase exercise capacity by increasing the capacity of anaerobic and aerobic pathways. Results for L-arginine’s ability to increase skeletal muscle and strength are very limited.
3. There is limited evidence to support the use of this supplement in sports. Dosing and timing studies show extremely varied results, and more research is needed to strongly support the efficacy of l-arginine.
Overall, L-arginine is safe, exists naturally in our food supply, and the body can produce plenty on its own. For the most part, it may just add to your credit card statements instead of adding to actual progress in the gym. However, if you want to experiment, it won’t hurt!