Effects of acute beta-alanine supplementation on post-exertion rating of per-ceived exertion, heart rate, blood lactate, and physical performance on the 6-minute race test in middle-distance runners.

Introduction: Background: the use of beta-alanine (BA) to increase physical performance in the heavy-intensity domain zone (HIDZ) is widely documented. However, the effect of this amino acid on the post-exertion rating of perceived exertion (RPE), heart rate (HR), and blood lactate (BL) is still uncertain. Objectives: a) to determine the effect of acute BA supplementation on post-exertion RPE, HR, and BL in middle-distance athletes; and b) to determine the effect of acute BA supplementation on physical performance on the 6-minute race test (6-MRT). Material and methods: the study included 12 male middle-distance athletes. The de-sign was quasi-experimental, intrasubject, double-blind & crossover. It had two treat-ments (low-dose BA [30 mg·kg-1] and high-dose BA [45 mg·kg-1]) and a placebo, 72 hours apart. The effect of BA was evaluated at the end of the 6-MRT and post-exertion. The variables were RPE, HR and BL, and 6-MRT (m) distance. The statistical analysis included a repeated-measures ANOVA (p < 0.05). Results: the analysis evidenced no significant differences at the end of 6-MRT for all variables (p ˃ 0.05). However, both doses of BA generated a lower post-exertion RPE. The high dose of BA caused significant increases in post-exertion BL (p ˂ 0.05). Conclusion: acute supplementation with BA generated a lower post-exertion RPE. This decrease in RPE and the post-exertion BL increase could be related to an increase in physical performance in HIDZ.

Introducción: Introducción: el uso de beta-alanina (BA) para aumentar el rendimiento físico en zo-nas con dominio de alta intensidad (HIDZ) está ampliamente documentado. Sin em-bargo, el efecto de este aminoácido sobre el índice de esfuerzo percibido (RPE), la frecuencia cardíaca (HR) y el lactato sanguíneo (BL) aún es incierto. Objetivos: a) determinar el efecto de la suplementación aguda de BA sobre el RPE, la HR y el BL posesfuerzo; y b) además del rendimiento en la prueba de carrera de 6 mi-nutos (6-MRT), en atletas de media distancia. Material y métodos: el estudio incluyó a 12 atletas masculinos de media distancia. El diseño fue cuasiexperimental, intrasujeto, doble ciego y cruzado. Incluyó dos trata-mientos (BA en dosis baja [30 mg·kg-1] y BA en dosis alta [45 mg·kg-1]) y placebo, con 72 horas de diferencia. El efecto de BA se evaluó al final de los 6-MRT y posesfuerzo. Las variables fueron RPE, HR y BL, y distancia en 6-MRT (m). El análisis estadístico in-cluyó un ANOVA de medidas repetidas (p < 0,05). Resultados: el análisis no evidenció diferencias significativas al final de los 6-MRT pa-ra todas las variables (p ˃ 0,05). Sin embargo, ambas dosis de BA generaron un menor RPE posesfuerzo. La dosis alta de BA generó incrementos significativos en el BL poses-fuerzo (p ˂ 0,05). Conclusión: la suplementación aguda con BA generó un menor RPE posesfuerzo. Esta disminución del RPE y el aumento en el BL posesfuerzo podrían estar relacionados con un aumento del rendimiento físico en HIDZ.

Acute Supplementation with Beta-Alanine Improves Performance in Aerobic-Anaerobic Transition Zones in Endurance Athletes.

To determine the acute effect of low and high-dose BA trials on maximal aerobic speed (MAS) in endurance athletes. We hypothesized that high doses of BA have a greater effect than low doses, both compared to baseline.Twelve male endurance athletes volunteered for the study (age = 21.8 ± 2.37 years, weight = 69.8 ± 4.36 kg, height = 174 ± 5.45 cm, maximal oxygen uptake = 59.6 ± 3.77 mLO2·kg-1·min-1). The experimental design applied was randomized cross-over, double-blind. Treatment included three 6-minute run tests (6-MRT), the first as a baseline, then randomized 6-MRT with low (30 mg·kg-1) and high (45 mg·kg-1) dose BA trials. The 6-MRTs were separated by 72 hours. The main variable of the study was the distance (m) performed in the 6-MRT. Differences between tests were established through ANOVA and Tukey's multiple comparison tests (p < 0.05).The analysis showed significant differences between baseline and both doses (p < 0.001). No significant differences were observed between low and high-dose BA trials (p > 0.05).Both 30 and 45 mg·kg-1 of BA increased physical performance at maximal aerobic speed in endurance athletes. The acute intake formats described in the present investigation may be helpful for endurance athletes training and competing in aerobic-anaerobic transition zones.

Effects of Beta-Alanine Supplementation on Physical Performance in Aerobic-Anaerobic Transition Zones: A Systematic Review and Meta-Analysis.

Beta-alanine supplementation (BA) has a positive impact on physical performance. However, evidence showing a benefit of this amino acid in aerobic-anaerobic transition zones is scarce and the results controversial. The aim of this systematic review and meta-analysis is to analyze the effects of BA supplementation on physical performance in aerobic-anaerobic transition zones. At the same time, the effect of different dosages and durations of BA supplementation were identified. The search was designed in accordance with the PRISMA® guidelines for systematic reviews and meta-analyses and performed in Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2010 and 2020. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the Time Trial Test (TTT) and Time to Exhaustion (TTE) tests, the latter separated into the Limited Time Test (LTT) and Limited Distance Test (LDT). The analysis was carried out with a pooled standardized mean difference (SMD) through Hedges' g test (95% CI). Nineteen studies were included in the systematic review and meta-analysis, revealing a small effect for time in the TTT (SMD, -0.36; 95% CI, -0.87-0.16; I2 = 59%; p = 0.010), a small effect for LTT (SMD, 0.25; 95% CI, -0.01-0.51; I2 = 0%; p = 0.53), and a large effect for LDT (SMD, 4.27; 95% CI, -0.25-8.79; I2 = 94%; p = 0.00001). BA supplementation showed small effects on physical performance in aerobic-anaerobic transition zones. Evidence on acute supplementation is scarce (one study); therefore, exploration of acute supplementation with different dosages and formats on physical performance in aerobic-anaerobic transition zones is needed.

[The effect of supplementation with L-arginine and L-citrulline on physical performance: a systematic review]. / Efecto de la suplementación de L-arginina y L-citrulina sobre el rendimiento físico: una revisión sistemática.

INTRODUCTION: Introduction: the amino acids L-arginine (L-arg) and L-citrulline (L-citr) have been used in sports nutrition, and it is believed that they have an effect on physical performance. However, current information is varied and inconclusive. Objective: to review and analyze the scientific evidence in the last ten years, which reflects a connection between the effect of L-arg and L-citr supplementation and physical performance. Material and method: this study is a systematic review of articles previously published, following the PRISMA model. Those articles published between 2008 and 2018 that connected the effect of L-arg and L-citr supplementation with physical performance were analyzed. The electronic search was performed on Web of Science, Scopus, Sport Discus, PubMed, and Medline. All articles using a supplementation protocol with these amino acids, separately or in groups, were selected. Results: a total of 38 articles were found, which were stratified according to the established protocol: a) supplementation with L-arg (n = 19); b) supplementation with L-arg and L-citr (n = 1); and c) supplementation with L-citr (n = 18), whether of short or prolonged duration. Conclusion: there is evidence that L-citr works better as ergogenic than L-arg does on physical performance, since L-citr showed a positive effect on the rate of perceived exertion and muscular pain, in addition to a decrease in lactate concentrations and time in maximum tests. However, there is not enough evidence to establish a beneficial L-citr dosage for physical performance.

INTRODUCCIÓN: Introducción: los aminoácidos L-arginina (L-arg) y L-citrulina (L-citr) se han utilizado dentro de la nutrición deportiva y se cree que ejercen un efecto sobre el rendimiento físico. Sin embargo, la información existente es variada y poco concluyente. Objetivo: revisar y analizar la evidencia científica existente dentro de los últimos diez años que relacionó los efectos de la suplementación con L-arg y L-citr sobre el rendimiento físico. Material y método: el estudio corresponde a una revisión sistemática de estudios previamente publicados, siguiendo el modelo PRISMA. Se evaluaron artículos publicados entre los años 2008 y 2018 que relacionaron la suplementación de L-arg y L-citr sobre el rendimiento físico. La búsqueda electrónica se realizó a través de Web of Science, Scopus, Sport Discus, PubMed, Medline. Se incluyeron todos los artículos que utilizaron un protocolo de suplementación de estos aminoácidos por separado o en conjunto. Resultados: se encontraron 38 artículos, los que se estratificaron según el protocolo utilizado: a) suplementación con L-arg (n = 19); b) suplementación con L-arg y L-citr (n = 1); y c) suplementación con L-citr (n = 18), tanto de corta duración como prolongada. Conclusión: existe evidencia de que la L-citr puede funcionar mejor como ayuda ergogénica que la L-arg sobre el rendimiento físico, ya que la L-citr mostró un efecto positivo sobre la percepción subjetiva del esfuerzo y el dolor muscular, además de una disminución en las concentraciones de lactato y una disminución del tiempo en pruebas máximas. Sin embargo, aún falta evidencia para establecer la dosis de L-citr beneficiosa para el rendimiento físico.