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

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

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

Conditions
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High Nitrate Dose, Moderate Nitrate Dose, Low Nitrate Dose, Nitrate-depleted Dose

Intervention / Treatment
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* Dietary Supplement: BR-HIGH
* Dietary Supplement: BR-MOD
* Dietary Supplement: BR-LOW
* Dietary Supplement: PL


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: In a double-blind, randomised, crossover design, participants were assigned to four experimental trials to consume a total of 4 beetroot juice shots during each condition: (a) 4 x 70 ml of nitrate-depleted beetroot juice for placebo (PL), (b) 1 x 70 ml of nitrate-rich beetroot juice 3 x 70 ml nitrate-depleted beetroot juice for a low dose of nitrate-rich beetroot juice (BR-LOW;  6.5 mmol of nitrate total), (c) 2 x 70 of nitrate-rich beetroot juice and 2 x 70ml of nitrate depleted beetroot juice for a moderate dose of nitrate-rich beetroot juice (BR-MOD;  13 mmol of nitrate total), and (d) 4 x 70 ml of nitrate-rich beetroot juice for an elevated dose of nitrate-rich beetroot juice (BR-HIGH;  26 mmol of nitrate total).
Masking: Double


Arms and Interventions

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

What is the study measuring?
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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 |