L-Arginine

What it is

L-arginine is an amino acid that serves as the substrate for nitric oxide synthesis, which helps regulate blood vessel dilation and blood flow to working muscle. Supplement marketing positions it as a "pump" and endurance aid, though much of the orally ingested dose is metabolized in the gut and liver before reaching circulation.

Benefits

May modestly improve aerobic capacity (VO2max) and, less reliably, anaerobic output; evidence does not support it for acute strength gains. Effects in trials cluster around acute doses of about 0.15 g per kg body weight 60-90 minutes before exercise, or roughly 1.5-2 g/day over several weeks for aerobic outcomes.

When to take it

For acute use, take 60-90 minutes before exercise to allow plasma levels to rise. Chronic aerobic protocols dose daily over 4 or more weeks.

Side effects

Generally well tolerated; higher doses can cause gastrointestinal upset such as nausea, bloating, and diarrhea. May lower blood pressure, which can matter for people on blood-pressure or nitrate medications.

Sources

• Effects of Arginine Supplementation on Athletic Performance Based on Energy Metabolism: A Systematic Review and Meta-Analysis (PMC)
• The effect of L-arginine supplementation on maximal oxygen uptake: A systematic review and meta-analysis
• Acute supplementation of L-arginine affects neither strength performance nor nitric oxide production (PubMed)

Products containing L-Arginine

No products in our database contain this ingredient yet.