Nearly 30 years ago, scientists identified a natural gas produced in the body that relaxes smooth muscles in the blood vessels, increasing oxygen and blood flow. Since then, more than 30.000 scientific papers have been published acknowledging Nitric Oxide’s crucial role in vasodilation and cell communication (*1).
Nitric oxide (NO) is a natural gas produced in the body through the work of specific enzymes called nitric oxide synthases that break down the amino acid arginine. NO acts as an important signalling molecule in the vascular system, dilating blood vessels and increasing blood flow and nutrients delivery to muscle cells.
Nitric oxide’s vasodilation effect is extremely important for athletes – especially for bodybuilders – as an increase in nutrient and oxygen delivery means you’ll be able to exercise for longer, no matter what your sport is.
During physical activity, there’s an increase in cardiac output and blood flow redistribution to muscle fibres. As you exercise, muscles become oxygen-depleted. In the absence of oxygen, the body begins to produce lactic acid which will eventually lead to muscle fatigue – to the extent that you can exercise no more.
Nitric oxide reduces the amount of lactic acid produced during exercise and extends the amount of time until exhaustion. By speeding up the delivery of oxygen and nutrients to the muscles under stress, nitric oxide improves their response to exercise and so increases sports performance.
It is also known to speed up the removal of the exercise-generated ammonia and increase glucose uptake by cells (*3).
The main ingredients of nitric oxide supplements are arginine and citrulline. These two amino acids are known to be nitric oxide precursors and so supplementing with arginine and citrulline can improve nitric oxide serum levels.
Research highlights arginine’s role in reducing exercise-induced increase in plasma lactate and ammonia (*4), therefore extending time until muscle failure. Taken together with BCAAs and glutamine, arginine can improve training efficiency by increasing blood oxygen-carrying capacity (*5).
But perhaps one of the most important effects of arginine supplementation for bodybuilders is its ability to stimulate growth hormone production. Scientific research shows that resting growth hormone levels increase with oral ingestion of L-arginine combined with exercise (*6), (*7).
This is mainly due to arginine’s ability to suppress somatostatin secretion, a hormone that inhibits growth hormone (*8). As we all know, growth hormone are responsible for cell and tissue growth, making it absolutely essential for muscle growth.
As you can see, arginine’s usefulness goes way beyond its ability to stimulate NO synthesis. As demonstrated by scientific studies, arginine can have a direct impact on muscle growth.
Citrulline is another amino acid that can efficiently restore nitric oxide production, due to having a higher absorption rate compared to arginine. It can be of particular interest when the body’s arginine availability is limited (*9).
We now understand why nitric oxide supplements are very popular among athletes and bodybuilders – they promote vasodilation and help the body to deliver precious nutrients to the muscles cells and so improve sports performance. Gym goers love to feel the pumping effect given by NO supplements.
Arginine and citrulline are two effective ingredients in increasing nitric oxide productions and can, at times, deliver other benefits that directly impact muscle growth. You can choose from high bioavailability forms such as Citrulline Malate and Arginine Alpha Ketoglutarate.