So what is nitric oxide? NO is a simple, unstable, free form gas consisting of one atom of nitrogen and one atom of oxygen. It can be produced by bacteria, or any situation where nitrogen burns, such as lightning, or car exhaust. It is also produced naturally in the body by various types of cells. It wasn’t thought to be that important in the metabolic functioning of higher organisms until ground-breaking research by pharmacologists Furchgott, Murad, and Ignarro showed just how important NO was for the proper and healthy functioning of the cardiovascular system. The researchers discovered that NO produced by one cell, could rapidly penetrate adjacent membranes and tissues and regulate the function of surrounding cells. That a gas could act as a cellular signalling system represented an entirely new concept in biology, and for this, the three men were awarded the 1998 Nobel Prize in medicine.

The walls of blood vessels are smooth muscle tissue, lined with endothelium cells. These cells produce nitric oxide to signal the surrounding muscle tissue to relax. The resulting expansion in the diameter of the blood vessels (known as vasodilation) reduces pressure inside the vessels, and allows blood to circulate more easily. This increases blood flow to the heart, liver, kidney and other vital organs. In addition, NO was shown to improve circulation by inhibiting both platelet aggregation (ie: clotting), and the build up of plaque on the inside of blood vessel walls.

Research indicates other functions performed by NO. Nerve cells were found to use it to activate other cells in the region, thereby regulating certain nervous system functions. White blood cells such as macrophages, produce NO to help kill invading bacteria or other parasites. Perhaps because it has a beneficial effect on blood flow, NO helps decrease the risk of transplant or implant rejections, and has been used to treat erectile dysfunction. Enhanced ciculation through organs like the liver and kidney help support improved detoxification of the body.

Okay, so now we know some of the things NO does for the metabolism. The question is, "How is this important for the performance athlete?" Well, increased blood flow to the vital organs, also means increased blood flow to muscle tissue. This, in turn, means enhanced nutrient delivery to, and absorption by muscle cells, and faster recovery.....things that are vital for building serious muscle as quickly as possible. Improved circulation also enhances oxygen delivery to cells, which helps support greater energy and stamina in the gym.

There is another big benefit for the hardcore bodybuilder. Blood rushes to muscle tissue that is placed under stress, causing the muscle to fill with blood, and get larger and harder. Anybody who has done several sets of dumbell or barbell curls to failure....to the point where the muscle is burning so much, it feels like it’s on fire......knows exactly what I’m talking about. The bicep gets hard as a rock, and expands to the point where it feels like it is going to explode. As bodybuilders, we live for the feeling of this "pump". If your blood vessels are dilated through enhanced nitric oxide production, blood flow to the muscle during stress is increased, resulting in an even greater pump, and a larger and harder appearance to the muscle. This expansion of the muscle fiber is known as myodilation. Aside from myodilation, the greater pump also makes veins and arteries more noticeable, enhancing the vascular appearance that so many bodybuilders strive to achieve. And, as long as we are on the subject of larger and harder, one of the side effects of increased nitric oxide production in the body, may be better sexual performance.

So, for bodybuilders and other performance athletes, the benefits of enhanced metabolic NO production appear to be real, and well supported by scientific evidence. In my opinion, this is no fad. For people training only occasionally...the dilletantes and the "weekend warriors"....taking an NO stimulator is not going to make a huge difference in results. But for the serious athlete, who trains hard, and on a regular, systematic basis, and is focused on results, an NO stimulator should be an indispensable part of their daily nutrition. I sure wouldn’t want to go up against a guy who was taking one on a regular basis, if I wasn’t. Why would I want to give up that competitive advantage? Why would I not want to look as big and hard as I possibly can?

The amino acid L-Arginine is an important intermediary in the production of NO. As such, while there may be many NO products out there, virtually all of the formulas rely on a few key derivatives of L-Arginine to enhance metabolic NO production. The most effective of these compounds are Arginine Alpha Ketoglutarate (AAKG) and Arginine Ketoisocaproate (AKIC). There are pure NO stimulators such as API’s Nitric X, and then, sometimes, NO stimulators are combined with other performance enhancers such as creatine, citrulline, vitamins and antioxidants, for a pre-workout specialty product. API’s Muscle Assault is an example of this pre-workout performance booster.

References

Ignarro LJ, Role of Nitric Oxide as a Signalling Molecule in the Cardiovascular System, Proceedings of the Conference of the Japan Society of Medical Electronics and Biological Engineering, 4552A, Vol 42, Page 5, 2003

Grange RW, Isotani E, Lau KS, Kamm KE, Huang PL, Stull JT. Nitric oxide contributes to vascular smooth muscle relaxation in contracting fast-twitch muscles. Physiological Genomics Vol 5, page 44, 2001.

Boger RH, Bode-Boger SM, Thiele W et al., Restoring vascular nitric oxide formation by L-arginine improves the symptoms of intermittent claudication in patients with peripheral arterial occlusive disease. Journal of the American College of Cardiology. Vol. 32:13, pages 36-44, 1998.

Hambrecht R, Hilbrich L, Erbs S. Et al., Correction of endothelial dysfunction in chronic heart failure: additional effects of exercise training and oral L-arginine supplementation. Journal of the American College of Cardiology. Vol. 35:7, pages 6-13, 2000.

Maxwell AJ, Zapien MP, Pearce GL et al. Randomized trial of a medical food for the dietary management of chronic, stable angina. Journal of the American College of Cardiology. Vol. 39, pages 37-45, 2002.

Jeevanandam M, Petersen SR. Substrate fuel kinetics in enterally fed trauma patients supplemented with arginine alpha ketoglutarate. Journal of Clinical Nutrition, Vol. 18(4):2, pages 9-17, August 1999.

Gonzalez-Cadavid NF, Rajfer J. Therapeutic stimulation of penile nitric oxide synthase (NOS) and related pathways. Drugs Today, Vol. 36, pages 163-174, 2000.

Moody JA, Vernet D, Laidlaw S, Rajfer J, Gonzalez-Cadavid NF. Effects of long-term oral administration of L-arginine on the rat erectile response. Journal of Urology, Vol. 158, pages 942-947, 1997.