Say No to NO Products!!

You’ve seen them in every fitness magazine on the market. You’ve seen them in GNC and in the supplement shop at your local gym. You may have even seen them on TV. What am I talking about? Those ads…you know the ones, touting the nitric oxide (NO) products as the next big thing in sports nutrition. To be honest, the mechanism seems plausible enough.

1. Take a supplement that is a precursor to nitric oxide.
2. The subsequent increase in nitric oxide causes vasodilation of the blood vessels.
3. This vasodilation increases nutrient delivery to the muscles.
4. The resulting effect is increased protein synthesis, hypertrophy, decreased catabolism and improved body composition.

So the theory makes sense, but is there any research to back-up the hefty claims? Unfortunately for the marketers of these products, there’s only been one decent study on arginine alpha ketoglutarate, the active ingredient in most nitric oxide products (arginine being the precursor to NO). It was completed down at Baylor, one of the foremost research facilities in the field of sports nutrition, and the results were less than stellar. Let’s take a closer look at this study…

Campbell et al actually completed two studies in one, a pharmacokinetic study, which is of little interest to us here, and a study measuring the effects of supplementation on training adaptations in resistance-trained men (1). In this second study, 35 adult, trained men ingested either 4 gms of arginine alpha ketoglutarate (AAKG) three times daily or placebo in a random, double-blinded protocol. The men performed periodized resistance training 4 days per week, two upper body days and two lower body days. At 0, 4 and 8 weeks, the following tests were completed: blood tests, one rep max bench press, isokinetic quadriceps muscle endurance, anaerobic power, aerobic capacity, total body water, body composition and psychometric parameter tests.

Results indicate there was a significant difference in one rep bench press (19# with AAKG vs. 6# with placebo) and anaerobic power, measured with the Wingate test. That said, there were no significant changes in fat-free mass, muscular endurance, aerobic capacity or catabolic markers. In other words, strength and power improved without ANY change in muscle hypertrophy or body composition. These results seem puzzling, but it is possible that the significant change in bench press strength was due to the placebo effect. The fact that the subjects were trained may have had an effect as well, but the 13# difference in bench press max is still somewhat difficult to explain. In addition, the only other study that addressed arginine and body composition found similar results…no significant differences in fat or lean tissue loss, muscle function or growth hormone levels (2).

The irony here is that most people take NO products because they want increased muscle size and improved body composition. The products are marketed in this light, but the research doesn’t seem to support these claims. I would pass on NO products for now, until we have more definitive studies showing consistently positive results.

References

1. Campbell B, Roberts M, Kerksick C, et al. Pharmacokinetics, safety and effects on exercise performance of L-arginine alpha ketoglutarate in trained adult men. Nutr 2006;22:872-881.
2. Walberg-Rankin J, Hawkins C, Fild D, Sebolt D. The effect of oral arginine during energy restriction in male weight trainers. J Strength Cond Res 1994;8:170-7.