Nitric oxide (NO) is a naturally occurring free radical in your body that supplement companies are claiming can actually boost your workout performance. Those looking to increase muscle mass are drawn to the claims that NO can enhance workout performance, increase stamina and promote muscle repair. Sounds like a magic little pill, but is it too good to be true?
As a vasodialator, NO expands the veins to lessen the force the heart must exert to pump the same amount of blood through the body. Since oxygen is carried in the blood, elevated levels of nitric oxide are said to enhance oxygen delivery to your muscles. NO boosters are being marketed as great way to improve your workout performance. The primary ingredient in NO boosters is arginine, and these supplements, typically sold in pill form, usually contain additional active and inactive ingredients.
The effects of nitric oxide on muscle growth and development are under investigation in the scientific community, but there are many studies that have given us a bit of insight. In a study performed by the International Journal of Sports Medicine 30 endurance athletes were given L-arginine, aspartate or a placebo. At the end of the study, evidence showed zero increase in endurance and blood vessel dilation in participants, and that nitric oxide does not promote muscle growth.
Another study from the Baylor University (Texas) examined the effects of arginine supplements during training on body composition in experienced exercisers. At the end of the trial, no significant differences were observed in participants’ body mass, fat mass or body fat percentage.
NO supplements haven’t been shown to increase muscle size or improve body composition, but there is some promising news when it comes to strength output. The same Baylor study showed a positive increase in the maximum amount of weight they can bench press for one rep. This tells us that NO supplements can help increase muscle strength through improved blood flow, but whether nitric oxide caused the increase in strength or whether it occurred as a natural effect of training is unknown.
While it’s not a miracle muscle builder, NO does have its proven health benefits. NO can prevent or treat heart disease and circulatory diseases, combat fatigue, stimulate the immune system, treat impotence, and fight cancer. Some studies have also suggested that the supplements can improve the function of blood vessels and lower blood pressure.
Long-term safety of arginine supplements is unknown and there is no recommended dosage, so speak with your doctor first. Side effects include diarrhea, weakness and nausea and increased nitric oxide levels might be dangerous for people with certain medical conditions, like kidney failure or cancer and those on other medications.
Dietary supplements are not regulated by the FDA, so there is no guarantee that any supplement is safe or effective. If you want to up your nitric oxide levels but don’t want to risk popping pills, you can obtain arginine through a healthy diet rich in brown rice, almonds, walnuts, pecans, sunflower seeds, raisins, chicken, and several plenty of plant-based foods. You may also be surprised to find out that while NO hasn’t been proven to enhance weight training performance, the act of weight training itself can increase the availability of nitric oxide stores in the body.