Do G894T Polymorphisms of Endothelial Nitric Oxide Synthase 3 (NOS3) Influence Endurance Phenotypes?

Endothelial nitric oxide (NO) synthase gene (NOS3) is taken into account as one of the main regulators of blood pressure and basal vascular dilation - two main factors found to be limiting for endurance performance. We compared genotypic and allelic frequencies of the NOS3 G894T polymorphism in two groups of men of the same Caucasian descent: elite endurance athletes (rowers; n=63) and sedentary controls (n=160). We have not found any statistical difference in G894T genotype and allele frequencies in endurance orientated athletes compared to sedentary controls. The difference in G allele frequency between the rowers and controls did not reach statistical significance (73.5% vs. 67.2%, P = 0.307), similar to genotype distribution amongst the rowers (58.7% GG; 39.4% GT; 6.4% TT) compared to controls (43.7% GG; 46.9% GT; 9.4% TT) (P=0.129). In summary, our results are in contradiction to the hypothesis that NOS3 G894T polymorphism is associated with the physical performance status in rowing. Of course, our findings do not mean that other polymorphisms in NOS3 gene do not have any beneficial effect on performance parameters, but to confirm that hypothesis, we need further studies.