Effects of Beetroot-Based Supplements on Muscular Endurance and Strength in Healthy Male Individuals: A Systematic Review and Meta-Analysis

Abstract

The aim of this study was to systematically review the current literature and analyze the effects of beetroot-based supplements (BRS) on muscular performance. Randomized controlled trials that assessed the acute or short-term effects of BRS administration on muscular endurance and/or strength in healthy male individuals were retrieved from PubMed, EMBASE, CENTRAL, and Web of Science databases from inception to February 20^th, 2023. In addition, we also searched preprint papers in medRxiv.org, bibRxiv.org; thesis and dissertations included in oatd.org; and clinical trials published in ClinicalTrials.gov. Data extraction, risk of bias, and study quality were assessed by 2 authors. Meta-analyses and subgroup analyses of standardized mean differences (SMD) were performed using a random-effects model. A total of 1486 records were identified in the databases and 2 were obtained by manual search in the reference list. Of those, 27 studies attended eligibility criteria and composed this systematic review. BRS administration resulted in a positive effect on muscular endurance (SMD: 0.31; 95% confidence interval (CI): 0.10 to 0.51; p < 0.01; n = 16 studies). There was an overall significative effect for muscular strength (SMD: 0.26; 95% CI: 0.03 to 0.48; p < 0.05; n = 18 studies), but a subgroup analysis showed that significant effects were found when strength was measured in a fatigued (SMD: 0.64; 95% CI: 0.25 to 1.03; p < 0.01), but not resting state. BRS administration have a small ergogenic effect on muscular endurance and attenuate the decline in muscular strength in a fatigued state in healthy male individuals.

KEY TEACHING POINTS

• Beetroot-based supplements can improve muscular endurance and attenuates the decline in muscular strength. These effects are attributed to the inorganic nitrate contained in these products, which ranged from 316–985 mg/day, ingested 2–3 hours before exercise.

• Beetroot-based supplements administration can generate a modest increase in the number of repetitions performed to failure or in exercise time to exhaustion, which may contribute to the performance and optimization of the results of people involved in isotonic exercises (e.g., resistance training).

• Beetroot-based supplements ingestion can improve muscular strength, particularly it aids in the recovery of muscular strength after a fatiguing task.

Keywords:

• Supplements
• functional foods
• muscle performance
• ergogenic aid

Author contributions

CM and JFE conceived the idea for the systematic review. JFE, CM, and RA conducted the study selection and data extraction. JFE and CMM conducted the methodological quality assessment. RA and GSA conducted the risk of bias assessment. JFE and CM conducted the statistical analyses. JFE drafted the initial manuscript. CM, CMM, RA, and GSA contributed to writing the manuscript. All authors approved the final version of the manuscript.

Compliance with ethical standards

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data extracted sheet that support the findings of this study are available from the corresponding author on request.

Additional information

Funding

JFE and GSA received a fellowship from the Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (Brazil). RA received a fellowship from Coordenação de Aperfeiçoamento de Pessoal de Ensino Superior (CAPES, Brazil).