Efeitos da suplementação aguda e crônica de nitrato no desempenho físico de mulheres praticantes de exercícios resistidos

Abstract

Introduction: Nitrate (NO3-), a dietary anion abundant in vegetables, is metabolized into nitrite (NO2-) and subsequently into nitric oxide (NO), increasing its plasma bioavailability. The growing interest in improving performance in resistance training has led people to seek nutritional supplements. This makes NO3-, with its potential physiological effects, improved mitochondrial efficiency, decreased oxygen cost, and enhanced vasodilation, a viable option. Justification: Although NO3- has shown positive results, especially in aerobic exercise, the literature lacks studies that consistently evaluate its effect in resistance training (RT). Furthermore, there is a lack of studies in female populations and in complete training sessions of longer duration. Objective: To evaluate the effect of acute and chronic NO3- supplementation on physical, hemodynamic, and psychophysiological factors in women practicing resistance training. Methodology: A randomized, double-blind clinical trial, approved by the Ethics and Research Committee (CAAE: 67603023.0.0000.5148), included 21 participants (age: 22.30 ± 2.87; body mass = 60.80 ± 8.01) divided into two groups: nitrate group (NG) (n = 11) and placebo group (PG) (n = 10) – all with experience in RT. Four in-person visits were conducted. In the first phase, familiarization was carried out, including physical and nutritional assessments, as well as measuring the loads to be used in the following days and signing the Informed Consent Form (ICF) and the Image Release Form (IR). In the second phase, the first experimental test was conducted without supplementation. The data collected were heart rate (HR), mean arterial pressure (MAP), and double product (DP) at rest and after the end of each exercise and 5 minutes after the end of the test session. Lactate levels at rest and at the end of the test, the number of repetitions on the leg extension machine, the pre-test and 5 minutes after the end of the last exercise isometric voluntary contraction (IVC) test, and the rating of perceived exertion (RPE). On the 3rd and 4th visits, the same protocol was followed with the intervention of acute and chronic supplementation, respectively. For statistical analysis, a two-way ANOVA test was performed to compare the conditions, with a significance level of p < 0.05. Results: An increase in repetitions was observed in both groups throughout the tests (p < 0.003). Despite the intra-group improvement over time, there were no differences between nitrate and placebo in any variable analyzed. Conclusion: Nitrate supplementation did not promote ergogenic effects on physical performance, lactate, RPE, and hemodynamic factors in women practicing resistance exercise. This suggests that the effects may depend on the type of exercise and the individual's physiological characteristics. Further research with greater control over the menstrual cycle and plasma concentrations of NO2- and NO is recommended for a better understanding of the results.