You know it's coming — that familiar pre-workout tingle. It creeps up your neck, sweeps across your face, and dances down your arms. Some people love it, and some don't. But have you ever stopped to wonder what causes that curious sensation? Is it a rash? A negative side effect? Do you have an allergy to pre-workout supplements? Or is there something beneficial about that pre-workout tingle or itch you feel a few minutes after drinking it?



In this article, I'll explain what makes you feel flushed and itchy or what gives you the tingles. However, I won't get into whether you should regularly use pre-workout or energy drinks. I did cover whether teens should use pre-workout supplements in the past, but I'll get into the pros and cons of pre-workout supplements at another time.



Vasodilation and Nitric Oxide: The Cause of the Pre-Workout Tingle



Vasodilation, dilation of your blood vessels, causes the pre-workout tingle. As your blood vessels widen, they allow more blood, oxygen, and nutrients to reach your muscles. The relaxation of blood vessels is a normal and healthy response. You dilate and constrict your blood vessels to regulate blood flow, ensuring that every part of your body, from your brain to your muscles, gets the oxygen and nutrients it needs.



Vasodilation plays a significant role during physical activity. When you exercise, your muscles need more oxygen to produce energy.



At the heart of this process is a molecule called nitric oxide. Nitric oxide signals the smooth muscle in your blood vessels to relax, causing them to expand.Förstermann, U., & Sessa, W. C. (2012). Nitric oxide synthases: regulation and function. European heart journal, 33(7), 829-837. Nitric oxide also signals the blood vessels in your muscles to expand, increasing blood flow and allowing more oxygen to reach your working muscles.



Various factors can reduce nitric oxide production, including aging, poor diet, lack of physical activity, and certain health conditions like diabetes and heart disease.



When nitric oxide levels decrease, it can lead to a condition known as endothelial dysfunction.Toda, N., & Okamura, T. (2013). The pharmacology of nitric oxide in the peripheral nervous system of blood vessels. Pharmacological reviews, 55(2), 271-324. The endothelium is the inner lining of your blood vessels. It plays a critical role in maintaining vascular health.



Endothelial dysfunction leads to vasoconstriction — the narrowing of blood vessels. This reduces blood flow, leading to high blood pressure and other cardiovascular issues.Lundberg, J. O., Weitzberg, E., & Gladwin, M. T. (2008). The nitrate–nitrite–nitric oxide pathway in physiology and therapeutics. Nature Reviews Drug Discovery, 7(2), 156-167. So, even though vasodilators have become extremely popular in pre-workout supplements, they also play an essential role in maintaining cardiovascular health for those who've developed heart disease.



Compounds That Trigger the Pre-Workout Tingle



Today, beta-alanine is the most popular vasodilator for pre-workout supplements, but other vasodilators exist. I'll briefly explain each.



Beta-Alanine



Beta-alanine is a non-essential amino acid that, when ingested, combines with histidine to form carnosine. Carnosine acts as a buffer, delaying the onset of muscle fatigue and enhancing your performance. However, when beta-alanine binds to nerve receptors, it can cause a sensation known as paresthesia (par·es·the·si·a) — the infamous pre-workout tingle or a feeling like you're getting poked with pins and needles.



A systematic review published in the journal Amino Acids examined 15 studies on beta-alanine. The authors found that beta-alanine supplementation improved performance in high-intensity exercises lasting 1-4 minutes by 2.85%.Hobson, R. M., Saunders, B., Ball, G., Harris, R. C., & Sale, C. (2012). Effects of β-alanine supplementation on exercise performance: a meta-analysis. Amino acids, 43(1), 25-37.