Nitrate, Placebo - Control
Conditions
Keywords
nitrate, beetroot, team sports, female athletes
Brief summary
A randomized, double-blind, placebo-controlled study investigates the effects of 5 days of nitrate-rich beetroot juice supplementation (70 mL·day-¹; 6.4 mmol NO₃-·day-¹) on physical performance in female basketball players. Performance will be evaluated using jump, 30-m sprint, agility, and isometric mid-thigh pull (IMTP) tests, while RPE and potential side effects will be assessed through questionnaires. The study aims to address the limited evidence regarding the ergogenic effects of beetroot juice supplementation in female team-sport athletes.
Detailed description
Although beetroot juice supplementation, primarily due to its high inorganic nitrate (NO₃-) content, has been associated with improvements in endurance and high-intensity intermittent exercise performance, its potential ergogenic effects in team sports remain unclear, particularly in female athletes. This knowledge gap is especially relevant in basketball, a sport characterized by repeated bouts of sprinting, jumping, accelerating, decelerating, and changing direction. Therefore, this randomized, double-blind, placebo-controlled study aimed to investigate the effects of 5 consecutive days of nitrate-rich beetroot juice supplementation (70 mL·day-¹, providing 6.4 mmol NO₃-·day-¹) on physical performance in female basketball players. Following the supplementation period, performance was assessed through jumping performance, 30-m sprint, agility, and isometric mid-thigh pull (IMTP) tests. Additionally, rating of perceived exertion (RPE) and potential side effects associated with beetroot juice supplementation were assessed using questionnaires.
Interventions
OTHERPlacebo
Participants consumed one 70-mL serving of nitrate-depleted beetroot juice placebo (0.04 mmol of NO₃-; Beet-It-Pro Elite Shot, James White Drinks Ltd., Ipswich, UK) daily for 5 consecutive days.
DIETARY_SUPPLEMENTBeetroot juice supplementation
Participants consumed one 70-mL serving of nitrate-rich BJ (6.4 mmol of NO₃-; Beet-It-Pro Elite Shot, James White Drinks Ltd., Ipswich, UK) daily for 5 consecutive days. On the final supplementation day, BJ was consumed 3 h before the testing session.
Sponsors
Universidad Pontificia Comillas
Universidad Francisco de Vitoria
Central Queensland University
Universidad Complutense de Madrid
Universidad de Cadiz
University of Tehran
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Masking description
In addition to the participants, the investigators responsible for performance testing and data analysis will remain blinded to group allocation until completion of data collection and statistical analyses.
Intervention model description
This study will use a randomized, double-blind, placebo-controlled, parallel-group design. Female basketball players will be randomly allocated to either a nitrate-rich beetroot juice supplementation group (70 mL·day-¹, providing 6.4 mmol NO₃-·day-¹) or a placebo group for 5 consecutive days. Following the supplementation period, physical performance will be assessed using jump, 30-m sprint, agility, and isometric mid-thigh pull (IMTP) tests. Rating of perceived exertion (RPE) and potential supplementation-related side effects will also be assessed.
Eligibility
Sex/Gender
FEMALE
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Female basketball players aged 18-35 years. * Currently participating in natitional competitive basketball. * Able to complete all supplementation and testing procedures.
Exclusion criteria
* Presence of any chronic disease or medical condition that could affect physical performance or interfere with the study procedures. * Presence of any injury during the month prior to the study that could limit participation in the physical performance tests. * Known intolerance or allergy to beetroot or other nitrate-rich vegetables (e.g., beetroot, lettuce). * Use of medications or dietary supplements that could potentially influence nitrate metabolism or physical performance during the study period.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Changes in maximal isometric handgrip strength (N) | 1-week | Isometric Mid-Thigh Pull (IMTP): Lower-body maximal isometric strength will be assessed using the isometric mid-thigh pull (IMTP) performed on VALD ForceDecks force platforms (VALD Performance, Brisbane, Australia). Participants will adopt a standardized mid-thigh pull position with the knees and hips slightly flexed and will be instructed to pull against an immovable bar as hard and as fast as possible. Ground reaction force will be recorded by the force platforms throughout each maximal effort. Peak force will be expressed both as absolute force (N) and relative to body mass (N·kg-¹). Participants will perform maximal trials separated by an appropriate recovery period, and the best trial will be retained for analysis. |
| Changes in maximal jump height (cm) | 1-week | Maximal Jump Height: Lower-body explosive performance will be assessed using the squat jump (SJ), countermovement jump (CMJ), and countermovement jump with arm swing (CMJ-AS). Jump performance will be measured using an OptoJump Next system (Microgate, Bolzano, Italy). Participants will perform maximal-effort trials for each jump condition following standardized instructions. Maximal jump height (cm) will be recorded for each jump type, and the best performance will be retained for analysis. Changes in maximal jump height following 5 days of supplementation will be compared between the nitrate-rich beetroot juice and placebo conditions. |
| Changes in sprint time (s) | 1-week | Sprint performance will be assessed by measuring the time required to complete 10-m, 20-m, and 30-m sprints using Microgate photocell timing gates (Microgate, Bolzano, Italy). Participants will be instructed to sprint as fast as possible over the 30-m distance, with split times recorded at 10 m, 20 m, and 30 m. Sprint time will be recorded in seconds (s). Participants will perform maximal trials separated by an appropriate recovery period, and the best performance will be retained for analysis. |
| Changes in agility test (s) | 1-week | Modified T-Test Performance: Change-of-direction performance will be assessed using the modified T-test, with completion time measured using Microgate photocell timing gates (Microgate, Bolzano, Italy). Participants will be instructed to complete the standardized course as quickly as possible, incorporating forward sprinting, lateral shuffling, and backward running. Completion time will be recorded in seconds (s). Participants will perform maximal trials separated by an appropriate recovery period, and the best performance will be retained for analysis. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Saliva NO3- and NO2- Measurements | 1-week | Saliva samples were collected 150 min after BJ or the placebo ingestion and were stored at -20°C for four months until subsequent analysis. To confirm the effectiveness of BJ supplementation on nitrate (NO3-) and nitrite (NO2-) levels, saliva concentrations were measured using a nitric oxide assay kit (EMSNO K195325, Thermo Fisher Scientific, Roskilde, Denmark) according to the manufacturer's instructions and as reported in previous literature (Richard et al., 2018). All samples and standards were measured in duplicate and averaged. |
| Rating of percevied exertion (RPE) (measured using scale 6-20 points) | 1-week | Immediately after each physical performance battery, participants were asked for providing her RPE using a Borg scale from 6 to 20 points |
| Side Effects Associated With Beetroot Juice Supplementation | 1-week | The morning after the supplementation and testing session, participants will complete a questionnaire assessing potential side effects associated with beetroot juice or placebo ingestion. The questionnaire includes gastrointestinal upset, red urine, gastric reflux, mild nausea, muscle pain, headache, increased urine excretion, increased fatigue, and nervousness. Each side effect will be assessed using a dichotomous Yes/No response scale (No = 0; Yes = 1). The incidence of each side effect will be reported as the number and percentage of participants reporting the symptom. |
Countries
Spain
Contacts
STUDY_CHAIRAlvaro Lopez Samanes, PhD
Universidad Pontificia Comillas
Outcome results
None listed