by Alan E. Shugarman, M.S., R.D.
If you’re like me, you love to get in the gym and feel your muscles swell to eye-popping proportions during your workout. You crave that intense shirt-ripping pump because you know you’re getting a great workout. That’s where the NO factor comes in! When I say NO, I actually mean nitric oxide (NO), one of the hottest sports nutrition supplements around today. Everyone wants to know if and how it works and if there are any studies backing up its effectiveness.
In the human body, NO is an important signaling molecule that acts in many tissues to regulate various physiological processes including vasodilation (blood vessel expansion), brain neuron function, inflammation, apoptosis (programmed cell death), cellular protection, immune function and erection. Viagra actually works on the NO pathway. For our purposes, we are most interested in the vasodilation effects for increasing blood flow to the muscles and for erectile function.
Pump blood into your muscles
As you train, blood flows into your muscles causing a pump. NO products are focused on increasing your natural muscle pump. Weight trainers love to feel their muscles pumped because they know they are working the muscle and can “feel” it. The theory behind NO products is if you can get more blood into the muscles, you will have a greater pump effect and possibly better nutrient delivery. Many people believe the better the pump, the better the workout. The purpose of NO products is to increase the pump, causing your muscles to look and feel larger. Some proponents have tried to stretch NO’s impact to include increased strength as well, but several studies have shown it does not affect strength or number of weight-lifting reps. These same studies did not evaluate such areas as muscle size, pump, feel or perceived quality of a workout—the very benefits that have made NO products so popular in the marketplace.
If you’re looking for that extra muscle pump in the gym, here are some of the most popular NO boosting ingredients, so you gain a better understanding of how they work.
Nitric oxide boosting ingredients
L-Arginine
L-arginine is a non-essential amino acid that is formed from glutamic acid, ornithine and citrulline. Two enzymes that use the majority of the available L-arginine are arginase and nitric oxide synthase (NOS). Arginine, which can be found in nuts, fruits, meats and dairy, directly creates nitric oxide and citrulline. Several studies have shown the ability of oral arginine to stimulate vasodilation and NO synthesis with doses as small as 1.5 grams and other studies have used more than 20 grams per day. For the purposes of increasing NO production, a dose in the range of 3-5 grams per day would appear to be adequate.
Common Dose: 3-5 grams
Arginine Alpha-ketoglutarate (AAKG) and Arginine KIC (AKIC)
These two compounds deliver arginine along with either the kreb’s cycle compound alpha- ketoglutaric acid or ketoisocaproic acid, which can oxidize to HMB in the body. HMB is a bodybuilding supplement that has been studied for its ability to increase lean muscle mass. When taking AAKG or AKIC, realize they have lower percentages of arginine than L-arginine itself, so it takes far greater amounts to deliver a lot of arginine. Studies have not shown greater benefits of AAKG and AKIC compared to plain L-arginine alone, although both do deliver arginine. AAKG is 45-66% arginine. AKIC is 66% arginine.
Common Dose: 2-4 grams
L-Citrulline
L-citrulline is a non-essential amino acid. Like L-arginine and L-ornithine, L-citrulline is a metabolite in the urea cycle and is involved in liver detoxification and vasodilation pathways. Formed from glutamic acid and ornithine in the body, it is added to many formulas in an attempt to reduce the utilization of arginine in the urea cycle and at the same time, enhance the production of NO in the NOS pathway. When endogenous supplies of ornithine carbamoyltransferase are insufficient, supplemental L-citrulline has been shown to support ammonia incorporation and liver detoxification of ammonia. In turn, this supports the production of NO by sparing L-arginine.
Common Dose: 100-500 mg
NADH
NADH is known as nicotinamide adenine dinucleotide hydrogen. This molecule is an energy source for reactions in the body. NADPH is the phosphate version of the molecule and is required to manufacture NO in the NOS pathway. Many formulas add NADH in an attempt to boost NO production. It is highly unlikely that the tiny amount of NADH in the NO formulas actually has an affect on NO production.
Common Dose: 5-10 mg
L-Norvaline
L-Norvaline is an analog of the amino acid L-valine. Research shows that L-norvaline is a strong inhibitor of arginase activity because of its structural similarity to ornithine, which causes a feedback regulation on the activity of arginase. When you inhibit arginase, NO is produced continuously at a higher rate in the presence of NOS and adequate L-arginine. L-arginine is the limiting factor for NO production from NOS, so inhibiting the arginase enzyme effectively increases the production of NO by as much as 60%.
Common Dose: 100-200 mg
Gynostemma Extract
Commonly known as jiaogulan, gynostemma pentaphyllum is a plant that grows wild in Asia and is similar to ginseng. Sometimes called “southern ginseng,” this adaptogenic herb contains various saponins known as gypenoside alkaloids. There are 82 different gypenosides in jiaogulan and research shows that they have some ability to induce the release of NO.
Common Dose: 100-200 mg
Combine with strength-boosters
Creatine is a very common addition to NO products on the market. Creatine is a proven strength and muscle-building product. When combined with the muscle pump effects of NO products, creatine brings the benefit of added water to the muscle for improved protein synthesis and even more muscle cell volumization. Plus by supplementing with creatine, you may be sparing more arginine for the NOS pathways since arginine is also used to form creatine in the body.
Summary
Research on NO products tells us that its benefits are not derived from increased strength or repetitions during workouts, but instead may come from the enhanced feel of the muscles engorged with blood for that incredible “pump.” Clearly, combination products would seem to be the most beneficial due to the multiple nutrients involved in the complex NOS pathway. If you decide to give NO products a try, stick with some of the ingredients and dosages mentioned in this article to have the best opportunity to see benefits from the products.
