Efeitos da suplementação de curto prazo de nitrato sobre a força e resistência muscular de indivíduos saudáveis: revisão sistemática e meta-análise

Abstract

Short-term nitrate supplementation has shown improvements in the performance of aerobic activities, but its effectiveness in activities of short duration, such as in muscular strength and endurance exercises, is still uncertain. Its ergogenic effects are attributed to nitric oxide, traditionally known for its vasodilator role, but which also seems to positively modulate intramuscular calcium handling and skeletal muscle contractility. Therefore, the aim of the present systematic review and meta-analysis was to determine the effects of short-term NO3- supplementation on muscular strength and endurance in healthy male individuals. PubMed, EMBASE, Web of Science, CENTRAL and LILACS databases were searched up to February 2021. Meta-analyses of standardized mean differences (SMD) were performed using a random-effects model to determine the effects of nitrate supplementation on muscular endurance and strength. Of the 1294 studies found, twenty-two were included in qualitative and quantitative analyses. From these, ten studies explored the effects of nitrate supplementation on muscular strength only; five, on muscular endurance only; and seven on both outcomes. Nitrate supplementation showed positive effects for muscular endurance (SMD = 0.37; 95% confidence interval (CI): 0.13, 0.62; P = 0.003) and for muscular strength post-fatiguing exercise (SMD = 0.39; 95% CI: 0.09, 0.70; P = 0.01). However, nitrate ingestion was not found to enhance muscular strength (SMD = -0.02; 95% CI: -0.25, 0.21; P = 0.84). Subgroup analyses showed that the training level, muscle group, type of contraction, supplemented dose and frequency do not influence the results found. Overall, nitrate supplementation appears to be a good strategy for healthy male individuals who want to improve muscle endurance and muscle strength post-fatiguing exercise.