INTRODUCTION: Inorganic nitrate (NO3-), which is abundant in some green leafy vegetables and beetroot, is sequentially reduced to nitrite (NO2-) and nitric oxide (NO) following ingestion. Dietary NO3- supplementation has been reported to have ergogenic effects on improving endurance (1), high intensity (2), and explosive efforts (3). However, the majority of the studies included only male athletes. The objective of this study was to analyse the influence of the acute supplementation with NO3rich beetroot juice (BJ) on the subsequent performance of professional female volleyball players agility ability. METHODS: 11 female professional (second Spanish national league) volleyball players with an experience higher than six years competed in the second Spanish national league (weight: height: 175.64 ± 6,7 cm; 72.25 ± 7,1 kg; age: 22.45 ± 3.1 years) articipated in this study. The study followed a randomised double-blind cross-over design. Before each testing session, the players ingested 140 mL of NO3rich BJ (~12.8 mmol NO3-) or a NO3depleted BJ (PLA), 150 minutes before. The players executed the 0-5-0 agility test and a modified T-test in each session. We assessed the differences between BJ and PLA using a Student t-test. The effect size (ES) was also calculated. We set the statistical significance as p<0.05. RESULTS: There were no significant differences between BJ and PLA for the 0-5-0 test (2.92 ± 0.16 vs 2.85 ± 0.17 s; p = 0.046; ES = 0.41 [-0.49 - 1.31]) nor the modified T-test (6.37 ± 0.28 vs 6.25 ± 0.35 s; p = 0.320; ES = 0.36 [-0.53 - 1.26]). CONCLUSION: Acute supplementation with NO3rich BJ was not effective in increasing performance in the agility ability of female volleyball players. The absence of significant differences could be attributed to a gender effect due to a reduction of NO2- to NO blunted, based on a greater oxidative skeletal muscle phenotype than males (4). Therefore, future studies are necessary to detect possible differences in response to NO3- in females compared to males.
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