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Get in the Flow

Five strength and blood-flow boosters that can jump-start your training.

We’re well aware that most people take preworkout supplements for the stimulant rush they provide. But there are a lot of ingredients in these powders that have benefits beyond jazzing you up. In the last issue, we looked at compounds that promote focus. This month, we examine ingredients that improve blood flow and nutrient delivery. We’ve grouped them together because increases in strength are commonly associated with increases in the blood flow needed to support the augmented metabolic and muscular demands. Most of these supplements can be found in today’s most potent preworkout formulas, but several of them produce results on their own, too. Here’s how they work and how to take them for best results.


What is it? Beta-alanine is a non-proteinogenic amino acid, which means it’s not involved in synthesizing proteins.In muscle, beta-alanine joins with the amino histidine to form the dipeptide carnosine. But that process is limited by how much beta-alanine is available in the body. So when beta-alanine is available in excess (i.e., because you’re supplementing with it), it leads to elevated muscle carnosine levels.

What does it do? Beta-alanine buffers muscle acidity during prolonged high-intensity exercise. Because one of the primary causes of fatigue during heavy exercise is metabolically mediated increases in acidity, it follows that increased carnosine levels would be beneficial to bodybuilders and strength athletes. Beyond its buffering effects, carnosine also acts as a potent antioxidant, which helps to maintain muscle performance during high-intensity training.

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 levels of fatigue compared to those who took a placebo. Such benefits also have been shown in resistance-trained men — four weeks of beta-alanine supplementation led to a 22 percent spike in the number of reps completed during workouts. 

Dosing:Take 2 to 3 grams 30 minutes before training. 


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

What does it do? NAC augments glutathione production and cysteine levels in muscle. Glutathione is a powerful antioxidant and free-radical scavenger that keeps oxidative stress in check under severe metabolic stress (like during intense exercise). Keeping free radicals under control during exercise has been shown to delay fatigue and increase training volume. Research also suggests that NAC works by preventing the breakdown of the 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 to 1,200 milligrams 30 minutes before training. Because 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 also can synthesize its own betaine through the oxidation of choline-containing compounds to assist in several important physiological functions, including increased cellular hydration, reduced inflammation, maintenance of intestinal function, DNA protection and buffering of homocysteine levels (from meat digestion). Most of betaine’s benefits occur because it’s a methyl donor, which means it sheds molecules called methyl groups to be used by other compounds in the body. One such compound is homocysteine, which bonds with methyl groups to form methionine, which in turn 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-blind, placebo-controlled study, researchers from the College of New Jersey concluded that two weeks of betaine supplementation significantly improved muscular endurance during squats and increased the total number of reps performed at 90 percent 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 six-week strength-training program experienced increases in bench-press strength, arm circumference and muscle mass while decreasing body fat by 7 percent. This was in contrast to the placebo group, which saw no gains in muscle mass or arm size and no loss of body fat.

Dosing: Studies show that as little as 2.5 grams per day can be effective, but some people work up to a maximum of 6 grams per day. Split the daily dose and take one 30 to 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 ofbeets (Beta vulgaris) that provides a rich source of dietary nitrates. 

What does it do? Nitrates increase nitric-oxide levels in the body, and NO is used by the lining of blood vessels to trigger relaxation. As a result, blood vessels dilate and blood flow increases. Research studies have noted the benefit beetroot extract can have on exercise and performance, because athletes who consume it before training experience increased endurance and time to exhaustion. Most recent research shows that taking beetroot extract (even for less than a week) significantly enhances muscle contractile efficiency, meaning you can push more weight using less energy.

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


What is it? Citrulline was first isolated from watermelon (its name was derived from the Latin word citrullus, meaning watermelon) and is produced in the body by the conversion or combination of other amino acids. One common pathway for citrulline production is in the conversion of arginine to nitric oxide, 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 resulting from heightened metabolism (like during exercise).

Malate, or malic acid, gives many sour fruits (e.g., green apples, sour grapes) their tartness. Malate is also an important intermediate in the Krebs cycle, which is basically how our bodies create energy. 

What does it do?Citrulline malate taken before workouts helps prevent muscle fatigue. It boosts ATP (energy) production during exercise and the rate of recovery after 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 preworkout dose of citrulline blunted exercise-induced fatigue, increased time to exhaustion and substantially decreased muscle soreness. 

Dosing:Take 6 to 10 grams of citrulline malate 30 minutes before training. Be sure to find a product that contains citrulline malate at a 2:1 ratio of citrulline to malate. <