L-citrulline
Amino acid used pre-training to support blood flow and training volume.
We recommend this on the evidence alone — we have no retailer partnership for it. Buy it wherever you like, and stick to the dose and form above.
What the evidence says
Pooled resistance-training trials show a modest increase in repetitions to failure and lower perceived soreness; effects on strength itself are small.
How it works
L-citrulline is a non-essential amino acid that acts as a potent precursor to L-arginine within the body. Unlike direct arginine supplementation, which is often degraded in the liver, L-citrulline bypasses first-pass metabolism, leading to a more efficient increase in systemic arginine levels. This process facilitates the production of nitric oxide, a signaling molecule that relaxes vascular smooth muscle.
What you may get out of it
Muscular Endurance
Enhances the ability to perform additional repetitions during high-volume resistance training sessions by improving ammonia clearance and nutrient delivery.
Post-Exercise Recovery
Assists in reducing the sensation of muscle soreness in the days following intense physical activity, likely through improved metabolic waste removal.
Vascular Support
Promotes vasodilation and improved blood flow, which may support better oxygen delivery to working muscle tissues during exercise.
What the research consistently shows
Resistance Training Performance
Systematic reviews of randomized controlled trials indicate that L-citrulline supplementation leads to a modest but consistent increase in the number of repetitions performed to failure. These effects are most pronounced in protocols involving high-volume resistance training rather than single-effort power tasks.
Muscle Soreness and Recovery
Meta-analyses have observed a reduction in delayed-onset muscle soreness (DOMS) when taken prior to exercise. While the mechanism is not fully understood, qualitative data suggests users experience less perceived discomfort 24 to 48 hours after training.
Aerobic and Anaerobic Power
Evidence regarding maximal strength and sprint performance is less consistent than endurance data. While some trials show slight improvements in power output, the overall impact on one-repetition maximum (1RM) strength is generally considered minor.
How to take it
For optimal results, L-citrulline is typically consumed in a dose of 6 to 8 grams approximately 30 to 60 minutes before physical activity. It is available as pure L-citrulline or L-citrulline malate; when using the malate form, a higher total weight is often required to reach the effective citrulline threshold. It can be taken on an empty stomach or with a light snack, as it is generally well-tolerated by the digestive system.
Realistic expectations
Unlike supplements that require a loading phase, the ergogenic effects on muscular endurance are often noticeable during the first training session. Individuals engaging in high-repetition weightlifting or high-intensity interval training tend to see the most benefit, whereas the effects may be negligible for those performing low-volume or light-intensity exercise.
What it doesn't do
L-citrulline is not a potent stimulant and will not provide a 'caffeine-like' energy boost. Evidence for its use in improving long-duration steady-state cardio or peak explosive power is weaker than its evidence for hypertrophy-style training. Individuals taking blood pressure medications or nitrates should consult a professional, as the supplement may have additive effects on blood pressure lowering.
This information is provided for educational purposes only and is not intended as medical advice or a substitute for professional health consultation. Synthesized by AI from established research on this category, with no fabricated citations or statistics.
⚠ Safety
Talk to your doctor or pharmacist before starting if you take any of the following:
- bp meds
⚕ This is general wellness information, not medical advice. It does not replace consultation with a healthcare professional. If you take prescription medication, are pregnant, or have a medical condition, talk to your doctor before starting new supplements.