What is Nitric Oxide? The Science Behind NO Boosters

Nitric oxide, like the laughing gas at the dentist’s office, or those tanks that people install in their cars to blast off at high speed? No. That would be nitrous oxide, a totally different substance.

So then, what is nitric oxide?

Nitric oxide (NO) is a molecule produced by our body that’s responsible for a variety of different features in helping the trillions cells in our body communicate with each other.

Over 60,000 studies have been completed on the subject. Three scientists have also been awarded the Nobel Prize of Medicine for discovering the signaling role of NO in 1998.

Here’s a list of functions it provides for our bodies:

  • transmits information between the brain and nerve cells throughout the body
  • helps immune system fight off bacteria and defends against tumors
  • improves sleep quality, memory strength, and the body’s senses
  • helps with gastric motility and reduced inflammation throughout your body
  • regulates blood pressure by dilating arteries
  • increases strength and endurance

As you can see, NO plays a massive importance in your body’s daily activities. However, when it comes to fitness, we’re only really concerned with the last two on the list: blood pressure and strength and endurance. But first, let’s see how this molecule was discovered.

The Origins of Nitric Oxide

viagraNitric oxide originally got its break thanks to its cardiovascular health benefits. Alfred Nobel, the founder of the Nobel Prize, was prescribed nitroglycerin by his doctor in order to help his heart problems. This happened over 100 years ago; the substance isn’t anything new.

At first he was skeptical since nitroglycerin was used in dynamite, but he soon realized the chemical also helped his heart condition subside. The nitroglycerin releases NO molecules which in turn widens blood vessels to increase the flow of oxygenated blood throughout the body.

Although your body produces NO naturally thanks to the interior lining of your arteries (endothelium), these can get clogged over time and reduce NO levels in your body. Nitroglycerin is prescribed to supplement your body’s lack of natural molecules, helping to prevent heart problems such as strokes.

Viagra, originally a medication for heart problems, soon became the popular choice for people with erectile dysfunction. The concept is the same, it widens blood vessels to increase blood flow. People soon realized that’s exactly how the penis works: more blood flow equals a better erect penis.1

How It Helps You Train Harder (and Longer)

NO boosters are the new secret weapon of bodybuilders and professional athletes alike. In simple terms, the increased blood flow that nitric acid provides allows your blood to deliver more nutrients like protein to your fatigued muscles, and quicker too. This can result in the appearance of larger muscles when they are subjected to stressful workouts. 2

Nitric oxide supplements include L-arginine and L-citrulline which support oxygenated blood flow to skeletal muscles and remove the lactic acid that build up in your muscles while working out. In turn, these result in faster recovery times and the ability to workout longer.3

Understanding the “Problem” NO Boosters Solve

sheer strengthWhen you exercise, your heart needs to pump more blood so your heart rate increases substantially to redistribute blood from inactive muscles to those that are being worked out. Your heart pumps out 2-3x more blood when you’re exercising.

At rest, only about 15-20% of your heart’s blood flow output is directed to skeletal muscles. However, when you’re active and working out, over 80% of the blood your heart is pumping is redirecting to muscles under stress.

This redistribution of blood flow is achieved by changes in systemic and localized vasomotor tone. The inner lining of your arteries contain a smooth layer of muscle that regulates this process automatically. By using the neurotransmitter noradrenaline, your body’s arteries and blood vessels are able to constrict in diameter if they’re inactive. This allows more blood to be redirected to the muscle groups that are being strained during exercise.4

NO Opens the Bloody Floodgates

blood cellsAs mentioned previously, when your body is under the stress of a heavy workout, blood flow can increase between 25 to 50 times more than when your body’s at rest.5

Arteries are considered the gatekeepers of blood flow to skeletal muscles. Arteries branch off into capillaries, which are able to transfer nutrients from the blood to muscle tissue. Precapillary sphincters control the flow of blood into capillaries, and if they’re constricted, the blood is redirected through metaarterioles, bypassing most capillaries. Essentially, your muscles miss out on vital nutrients carried in the blood.

Vasodilation, or the loosening of constriction, targets theses precapillary sphincters, letting blood flow through them freely. Although vasodilation occurs naturally by releasing nitric oxide with increased exercise, factors such as aging can reduce NO molecules in your body, thus causing quicker lactic-acid buildup and fewer nutrients from entering your muscles during training.

Debunking the Myths Behind NO Boosters

Up until this point, the purpose of NO boosters is clear: to increase workout longevity and heal muscles quicker. But, there’s a myth going around about these supplements that claims they’re able to increase your muscle mass. Although your muscles can appear larger while working out due to expanded blood vessels as stated before, Tod Cooperman M.D., President of ConsumerLab states:

“They won’t pump up your muscles — their main claim, but ‘nitric oxide’ supplements may help you exercise intensely a little longer.”

ConsumerLab also conducted clinical studies on NO boosters and found “[no] significant increase in muscle size or fullness with such supplements.”6 They have also noted that NO boosters don’t really provide you with NO molecules, which is a gas, but instead provide you with L-Arginine which increases your body’s production of the molecule.

Summing Up

In bodybuilding and other muscle strenuous exercises, your heart works harder to pump more blood to the muscle groups you’re working out. Naturally, your body produces nitric oxide which is responsible for opening the arteries and capillaries that direct oxygen and nutrients, such as protein, to the muscles being exercised. Due to aging and clogged arteries, NO can’t reach the muscles in need properly, making you tired quicker and your muscles more sore. Taking NO boosting supplements or eating these NO rich foods provides your body with the molecules it needs to help your muscles heals faster and allow you to work out longer. Hopefully you now know the answer to the question, “What is nitric oxide?”


  1. Clark, Jason. “What Is NO and How Does It Work?” Nutrition Express.
  2. South, Clayton. “Clayton’s Health Facts: NO Boosters” Bodybuilding.com.
  3. Clark, Jason. “What Is NO and How Does It Work?” Nutrition Express.
  4. Jacobs, Patrick. “Efficacy Of Dietary Supplementation For NO Synthesis” Bodybuilding.com.
  5. Segal S, Bearden SE. Organization and control of circulation to skeletal Muscle. In: Tipton, CM. editor. ACSM’S Advanced Exercise Physiology. place: Lippincott, Williams and Wilkins; 2006. p. 343-356.
  6. “Do NO Supplements Really Work for Bodybuilding and Athletics?” ConsumerLab.com. 2011.
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