Dr. Dwayne Jackson

The Vital Science Blog

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Stimulant-Free Preworkout Supplements 



In this second part of our “stimulant-free preworkout supplements” series we cover the 5 top strength and blood flow boosters. We have grouped them together because increases in strength are commonly associated with increases in blood flow needed to support the augmented metabolic and muscular demands. Most of these supplements can be found in today’s most potent pre-workout formulas, but many of them work great on their own too. Read on to find out how these top strength and blood flow boosters work and how to take them for best results.  



What is it? A non-proteinogenic amino acid, meaning that it is not involved in synthesizing proteins. In skeletal muscle, beta-alanine and histidine form the di-peptide carnosine—where the level of beta-alanine limits carnosine production. As such, when beta-alanine is available in excess (i.e., supplemented) it leads to elevated muscle carnosine levels.

What does it do? Elevated muscle carnosine levels increase muscle function and performance through its ability to buffer skeletal muscle pH (acidity) during prolonged high intensity exercise. Since one of the primary causes of fatigue during heavy exercise is metabolically mediated decreases in pH (or acidosis), then it follows why increased intramuscular carnosine levels would be beneficial to bodybuilders and strength athletes. Beyond its buffering effects, high muscle carnosine also acts as a potent antioxidant, which helps to maintain muscle performance during high intensity exercise.  

Several studies have shown that beta alanine supplementation increases strength and workout endurance. For example, in football players, 30-days of beta-alanine supplementation resulted in greater training volume and lower subjective indices of fatigue compared to those who took a placebo. Such benefits have been also shown in resistance trained men, where 4-weeks of beta alanine supplementation led to a 22% increase in the number reps completed during workouts. 

Dosing: Take 2-3 grams, 30 minutes prior to training. 



What is it? A water-soluble and highly bioavailable form of the amino acid cysteine. Unlike cysteine, NAC must be taken as a supplement, as it’s not available by any other dietary means.

What does it do? NAC augments glutathione production and cysteine levels in skeletal muscle. Glutathione is a powerful antioxidant and free radical scavenger, which keeps oxidative stress in check under severe metabolic stress (like during intense exercise). Keeping free radicals under control during exercise has ben shown to delay fatigue and increase training volume. Research also suggests that NAC works by preventing the breakdown of sodium-potassium pumps in muscle cells, which may serve to maintain muscle strength and prolong performance. 

Having high levels of cysteine in your muscles is good because cysteine can be converted to glucose when needed, thus sparing muscle mass in times of carb depletion. Finally, cysteine is a precursor to taurine production, which also has been shown to increase strength. 

Dosing: Take 600-1200 mg, 30 minutes prior to training. Since high doses may cause stomach upset, start with the lowest dose and work up. 



What is it? Also known as trimethylglycine or TMG, betaine is a derivative of the amino acid glycine and exists in foods like wheat, beets, spinach, and shellfish. The body can also synthesize its own betaine through the oxidation of choline-containing compounds to assist in several important physiological functions in our bodies. Some of the more important roles of betaine include, increased cellular hydration, reduced inflammation, maintenance of intestinal function, DNA protection, and buffering of homocysteine levels (from meat digestion). Most of betaine’s impotant roles occur because it is a methyl donor. As such, betaine promotes the methylation of homocysteine in the body to form methionine, which aids in creatine production and boosts protein synthesis for greater muscular gains. 

What does it do? Betaine has been scientifically shown to improve muscular endurance, especially under high power output. In a double blinded, placebo controlled study, researchers from the College of New Jersey concluded that 2 weeks of betaine supplementation significantly improved muscular endurance during squats and increased the total number of reps performed at 90% of peak power. Beyond improvements in muscular endurance, betaine supplementation has been shown to increase strength and muscularity. In a recent study published in The Journal of the International Society of Sports Nutrition, subjects who took betaine while completing a 6-week strength training program had increases in bench press strength, arm circumference, and muscle mass, while they decreased body fat by 7 percent. This was in contrast to the placebo group who saw no increase in muscle mass or arm size and no loss of body fat.

Dosing: Studies show that as little as 2.5g per day can be effective, but some people work up to a maximum of 6g per day. Split the daily dose and take one 30-90 minutes before training (or first thing in the morning on rest days) and another postworkout (or right before bed on rest days).



What is it? Beetroot extract is a reddish pink colored powder made from the roots of beets (Beta Vulgaris), which provides a very rich source of dietary nitrates. 

What does it do? Dietary nitrates increase nitric oxide (NO) levels in the body– NO is used by the endothelium to trigger relaxation in the smooth muscle. As a result, vasodilation is induced and blood flow increases. Research studies have noted the benefit beetroot extract can have on exercise and performance, as athletes who consume it before training experience increased endurance and time to exhaustion. Most recent research illustrates that taking beetroot extract (for less than even a week) significantly enhances muscle contractile efficiency, meaning you can push more weight with less energy cost.

Dosing: Take 500-750mg of high nitrate standardized beetroot extract, 30-60 minutes before training. 



What is it? A compound formed by chemical boding of the amino acid citrulline to malate. Citrulline was first isolated from watermelon, thus its name was derived from the Latin word citrullus, meaning watermelon. It is produced in the body by the conversion or combination of other amino acids. One very common pathway for citrulline production is in the conversion of L-arginine to nitric oxide (NO, a vasodilator), whereby NO synthase (an enzyme) oxidizes L-arginine to form NO and citrulline. In addition, citrulline is a key player in the urea cycle— a biological pathway by which we get rid of toxic ammonia from heightened metabolism (like during exercise). 

Malate or malic acid is found in many sour fruits (e.g., green apples, sour grapes) and it gives them their tartness. Malate is also an important intermediate in Kreb’s cycle (i.e., the citric acid cycle), giving it an important role in ATP (energy) production in the body. 

How does it work? Citrulline malate taken preworkout helps prevent muscle fatigue, as it increases energy (ATP) production during exercise and the rate of phosphocreatine recovery post-exercise. It also helps buffer ammonia and lactic acid produced during heavy training, thus extending exercise performance. Citrulline, converts to arginine (the precursor to NO) in the body and optimizes blood and nutrient delivery to working muscles. Recent research indicates that citrulline supplements can actually increase blood levels of arginine and nitric oxide more effectively than arginine ingestion. The overall effectiveness of this amino acid compound was recently highlighted in a study illustrating that a single pre-workout dose of citrulline blunted exercise-induced fatigue, increased time to exhaustion, and substantially decreased muscle soreness. 

Dosing: Take 6-10g of citrulline malate, 30 minutes prior to training. Be sure to find a product that contains citrulline:malate at 2:1.

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