The Effect of Nitric-Oxide-Related Supplements on Human Performance

Abstract

Nitric oxide (NO) has led a revolution in physiology and pharmacology research during the last two decades. This labile molecule plays an important role in many functions in the body regulating vasodilatation, blood flow, mitochondrial respiration and platelet function. Currently, it is known that NO synthesis occurs via at least two physiological pathways: NO synthase (NOS) dependent and NOS independent. In the former, L-arginine is the main precursor. It is widely recognized that this amino acid is oxidized to NO by the action of the NOS enzymes. Additionally, L-citrulline has been indicated to be a secondary NO donor in the NOS-dependent pathway, since it can be converted to L-arginine. Nitrate and nitrite are the main substrates to produce NO via the NOS-independent pathway. These anions can be reduced in vivo to NO and other bioactive nitrogen oxides. Other molecules, such as the dietary supplement glycine propionyl-L-carnitine (GPLC), have also been suggested to increase levels of NO, although the physiological mechanisms remain to be elucidated. The interest in all these molecules has increased in many fields of research. In relation with exercise physiology, it has been suggested that an increase in NO production may enhance oxygen and nutrient delivery to active muscles, thus improving tolerance to physical exercise and recovery mechanisms. Several studies using NO donors have assessed this hypothesis in a healthy, trained population. However, the conclusions from these studies showed several discrepancies. While some reported that dietary supplementation with NO donors induced benefits in exercise performance, others did not find any positive effect. In this regard, training status of the subjects seems to be an important factor linked to the ergogenic effect of NO supplementation. Studies involving untrained or moderately trained healthy subjects showed that NO donors could improve tolerance to aerobic and anaerobic exercise. However, when highly trained subjects were supplemented, no positive effect on performance was indicated. In addition, all this evidence is mainly based on a young male population. Further research in elderly and female subjects is needed to determine whether NO supplements can induce benefit in exercise capacity when the NO metabolism is impaired by age and/or estrogen status.

Effects of Pre-Workout Supplements on Power Maintenance in Lower Body and Upper Body Tasks

“…In past research examining the use of beta-alanine supplementation on improving jump performance, one of the individual ingredients within the SUP, resulted in an improvement in maximal and mean power during countermovement jumps [28]. The results from the countermovement vertical jump test from this study did not show the same response, likely due to the lack of chronic supplementation or the much lower dosage.…”

Endothelial nitric oxide synthase g894t (rs1799983) gene polymorphism in polish athletes

“…It has been suggested that an increase in NO production may facilitate oxygen and nutrients delivery to working muscles, thereby improving exercise tolerance and recovery [29]. Hence, the NOS3 gene, due to its central role in the production of NO in the vascular endothelium [6], became a candidate gene for association with athlete status or athletic performance.…”

Effects of Natural Nutritional Beverages on Anaerobic Exercise Performance

“…The AEC was then determined using the Weir equation, with an adjustment to the O2 caloric equivalent when the resting energy requirement (RER) became > 1. With the reduced AEC, the authors concur with previous work (Bescós et al, 2012) that NO3-supplementation is able to decrease the O2 cost during exercise via an improvement in energy production efficiency. A further finding of Pinna et al's (2014) study was an increased workload achieved at AT (6.7 ± 1.1 vs. 6.35 ± 1.0 kg·min -1 ) in the setting of no difference in V̇O2 at AT for the NO3-relative to the control group.…”

“…A number of studies have provided evidence to support the use of dietary NO3-supplementation during endurance exercise (Affourtit, Bailey, Jones, Smallwood & Winyard, 2016;Bescós, Sureda, Tur & Pons, 2012;Hoon, Johnson, Chapman & Burke, 2013;McMahon, Leveritt & Pavey, 2017;Pawlak-Chaouch et al, 2016) but the effects of NO3-supplementation during high anaerobic power exercise warrant deeper investigation (McMahon et al, 2017). Tests of anaerobic power involve evaluating the effectiveness of the anaerobic energy pathways: ATP-PC system and anaerobic glycolysis (Powers & Howley, 2015).…”