What’s the word on nitric oxide supplements?
These pre-workout products claim to improve exercise performance and muscle growth.
Nitric oxide is a gas, and in the body it acts as a signaling molecule telling the smooth muscle around blood vessels to relax. This allows blood vessels to dilate and move more blood, increasing blood flow to muscles being worked in training.
Nitric oxide is synthesized from arginine, an amino acid found in basically all protein-containing foods and some supplements as well. The problem with taking arginine is that it does not raise plasma arginine levels as much as taking citrulline, another amino acid. Citrulline converts to arginine in the kidneys.
Studies have found citrulline to be a generally effective supplement to improve your workout through increased strength endurance and power endurance. It doesn’t have HUGE effects, but taking consistently over time in conjunction with proper training and nutrition can lead to modest improvements. It can be found in different forms such as citrulline malate and L-citrulline, and it isn’t clear if one is significantly better than the other.
If you want to reap the benefits from citrulline, keep an eye on the dosage in your preworkout. General recommendations are for 8-9g citrulline malate or 4-5g L-citrulline. I personally take @pescience High Volume which has L-citrulline in the adequate dose.It’s best to take citrulline an hour or two before you start your workout.
-Katy Hair, RD, LDN, CNSC
Trexler ET, Persky AM, Ryan ED, Schwartz TA, Stoner L, Smith-Ryan AE. Acute Effects of Citrulline Supplementation on High-Intensity Strength and Power Performance: A Systematic Review and Meta-Analysis. Sports Med. 2019 May;49(5):707-718.
Schwedhelm E, Maas R, Freese R, Jung D, Lukacs Z, Jambrecina A, Spickler W, Schulze F, Böger RH. Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. Br J Clin Pharmacol. 2008 Jan;65(1):51-9.
Nuckols, G. Citrulline Supplementation Increases Strength Endurance. Monthly Applications in Strength Sport. 2019, May;3(5):63-73.