The Effect of Beetroot Juice Supplementation Dose on Neuromuscular Performance During Resistance Exercise

Dietary nitrate supplementation, administered in the form of nitrate-rich beetroot juice, has been shown to improve exercise performance and may have more pronounced effects on exercise that requires high-power and high-velocity muscle contraction such as weightlifting and body-mass resisted exercise (i.e, resistance exercise). However, limited data are available that have examined the potential performance enhancing effect of beetroot juice in resistance exercise. Moreover, there is no information on the dose of nitrate required for performance enhancing effects during resistance exercise which limits its widespread use to enhance performance. Therefore, the investigators will assess if supplementing the diet with nitrate-rich beetroot juice impacts resistance exercise performance (e.g., power, velocity), when compared to supplementing the diet with nitrate-depleted beetroot juice (i.e. placebo). The investigators will also investigate the dose-response effect of beetroot juice on resistance exercise performance by providing a low, moderate, and high nitrate dose of concentrated beetroot juice. The results of this study will improve understanding of whether beetroot juice influences resistance exercise performance and will provide insight on whether different doses of beetroot juice influence the efficacy of nitrate supplementation on resistance exercise performance. Together, these data will guide supplementation strategies for enhancing resistance exercise performance.

Study Overview

• Status: Recruiting
• Conditions: High Nitrate Dose; Moderate Nitrate Dose; Low Nitrate Dose; Nitrate-depleted Dose
• Intervention / Treatment: Dietary supplement: BR-HIGH; Dietary supplement: BR-MOD; Dietary supplement: BR-LOW; Dietary supplement: PL

Detailed Description

Supplementation with inorganic nitrate, which is most commonly administered in the form of concentrated nitrate-rich beetroot juice shots, has emerged as an ergogenic nutritional strategy. Beetroot juice ingestion has been reported to enhance endurance and high-intensity intermittent exercise performance in running and cycling. These improvements are attributed to augmented muscle contractility, force production and blood flow distribution, specifically in muscle groups comprised predominantly of type II muscle fibers. Together, such changes provide a strong physiological rationale supporting the potential for dietary nitrate to enhance high-power and high-velocity muscle contractions since type II muscle fibers are heavily activated during these tasks. However, the influence of dietary nitrate on resistance exercise performance is substantially underdeveloped with most previous studies having assessed the effect of nitrate supplementation on running and cycling endurance and high-intensity intermittent exercise. Moreover, there is no information on the dose of nitrate required to evoke ergogenic effects during resistance exercise, which greatly hinders the potential implementation of beetroot juice as a research-informed performance enhancing supplement for resistance exercise. Thus, the proposed project will investigate if acute dietary nitrate ingestion, provided as nitrate-rich beetroot juice, elicits improvements in various neuromuscular performance parameters (e.g., power, velocity) during resistance exercise performance when compared to supplementing the diet with a nitrate-depleted beetroot juice placebo. The investigators will also investigate the dose-response effect of beetroot juice on resistance exercise performance by providing low (70 ml i.e., ~6.5 mmol or ~400 mg of nitrate), moderate (140 ml i.e., ~13 mmol or ~800 mg of nitrate) and a high nitrate dose (280 ml i.e., ~26 mmol or ~1600 mg of nitrate) of concentrated beetroot juice. This project will provide insight to practitioners (coaches/athletes) aiming to enhance performance in settings where muscular power and speed are key determinants for success, as well as to scientists exploring the efficacy of beetroot juice as a form of dietary nitrate supplementation to improve muscle contractile function.

• Study Type: Interventional
• Enrollment (Estimated): 18
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Rachel Tan, PhD; Phone Number: 3105067041; Email: rachel.tan@pepperdine.edu
• Study Contact Backup: Name: Adam Pennell, PhD; Phone Number: 3105064162; Email: adam.pennell@pepperdine.edu

Study Locations

• United States
  • California
    • Malibu, California, United States, 90263
      • Recruiting
      • Pepperdine University
      • Contact: Rachel Tan, PhD; Phone Number: 310-506-7041; Email: rachel.tan@pepperdine.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Recreationally active males who performed resistance exercise at least twice weekly for the last two years

Exclusion Criteria:

• individuals with contraindications to exercise, cardiometabolic disease, currently consuming dietary supplements containing caffeine, sodium bicarbonate, creatine, beta-alanine, and/or NO precursor supplements (i.e., NO3-, arginine, citrulline, antioxidants), females, and smokers

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: BR-HIGH; Participants will ingest an elevated dose of nitrate 2.5 hours prior to exercise.	Dietary supplement: BR-HIGH; 4 x nitrate-rich beetroot juice shots (26 mmol of nitrate)
Experimental: BR-MOD; Participants will ingest a moderate dose of nitrate 2.5 hours prior to exercise.	Dietary supplement: BR-MOD; 2 x nitrate-rich beetroot juice shots + 2 x nitrate-depleted beetroot juice shot (12 mmol of nitrate)
Experimental: BR-LOW; Participants will ingest a low dose of nitrate 2.5 hours prior to exercise.	Dietary supplement: BR-LOW; 1 x nitrate-rich beetroot juice shot + 3 x nitrate-depleted beetroot juice shots (6 mmol of nitrate)
Placebo Comparator: PL; Participants will ingest a negligible amount of nitrate 2.5 hours prior to exercise.	Dietary supplement: PL; 4 x nitrate-depleted beetroot juice shots (0 mmol of nitrate)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Plasma nitrate	Plasma nitrate concentrations in each condition from blood samples draw at rest prior to exercise, and analyzed using gas phase chemiluminescence	Through study completion, at least 1 year
Plasma nitrite	Plasma nitrite concentrations in each condition from blood samples draw at rest prior to exercise, and analyzed using gas phase chemiluminescence	Through study completion, at least 1 year
Neuromuscular performance during countermovement jumps	Peak force will be measured using a force place.	Through study completion, at least 1 year
Neuromuscular performance during countermovement jumps	average propulsion force will be measured using a force place.	Through study completion, at least 1 year
Neuromuscular performance during countermovement jumps	rate of power development will be measured using a force place.	Through study completion, at least 1 year
Neuromuscular performance during countermovement jumps	peak positive power will be measured using a force place.	Through study completion, at least 1 year
Neuromuscular performance during countermovement jumps	concentric mean power will be measured using a force place.	Through study completion, at least 1 year
Neuromuscular performance during countermovement jumps	jump height will be measured using a force place.	Through study completion, at least 1 year
Neuromuscular performance during countermovement jumps	takeoff velocity will be measured using a force place.	Through study completion, at least 1 year
Neuromuscular performance during countermovement jumps	flight time will be measured using a force place.	Through study completion, at least 1 year
Neuromuscular performance during countermovement jumps	Peak force, average propulsion force, rate of power development, peak positive power, concentric mean power, jump height, takeoff velocity, flight time will be measured using a force place.	Through study completion, at least 1 year
Peak power	Power will be measured using a linear transducer with the highest value will be recorded for peak power	Through study completion, at least 1 year
Mean power	Power will be measured using a linear transducer and will be averaged across sets for the determination of mean power	Through study completion, at least 1 year
Mean velocity	Velocity will be measured using a linear transducer and will be averaged across sets for the determination of mean velocity	Through study completion, at least 1 year
Peak velocity	Velocity will be measured using a linear transducer the highest value will be retained for peak velocity	Through study completion, at least 1 year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mood	24 items representing six subscales (i.e., anger, confusion, depression, fatigue, tension, vigour; four-items per subscale) will be captured using a five-point Likert scale (i.e., 0 = not at all, 1 = a little, 2 = moderately, 3 = quite a bit, 4 = extremely)	Through study completion, at least 1 year

Collaborators and Investigators

• Sponsor: Pepperdine University
• Investigators: Principal Investigator: Rachel Tan, PhD, Pepperdine University

Study record dates

Study Major Dates

• Study Start (Actual): May 23, 2023
• Primary Completion (Estimated): April 28, 2024
• Study Completion (Estimated): June 30, 2024

Study Registration Dates

• First Submitted: June 28, 2023
• First Submitted That Met QC Criteria: July 16, 2023
• First Posted (Estimated): July 24, 2023

Study Record Updates

• Last Update Posted (Estimated): July 24, 2023
• Last Update Submitted That Met QC Criteria: July 16, 2023
• Last Verified: June 1, 2023

More Information

Terms related to this study

• Other Study ID Numbers: RT12

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation, upon request.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No