Protocol summary
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Study aim
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This study aims to evaluate the effect of training status on the Special Judo Fitness Test (SJFT) performance following beetroot juice ingestion.
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Design
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A crossover, placebo-controlled, double-blind, randomized, phase 3 clinical trial on 34 judo athletes. The RAND function of Excel software will be used for randomization.
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Settings and conduct
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Participants will perform two sessions of SJFT after beetroot or placebo supplementation. The number of throws (TT), heart rate (HR) immediately at the end of SJFT (HR0) and 1 minute after SJFT (HR1), SJFT index, rate of perceived exertion (RPE), muscle oxygenation, and plasma nitrate, nitrite and lactate levels will be measured. This study will use a double-blind method (participants and researchers). The study will take place in Ankara, Turkey.
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Participants/Inclusion and exclusion criteria
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Inclusion criteria:
Having at least a Purple Belt in Judo
Free from neuromuscular and musculoskeletal disorders
Non-smokers
Non-alcoholic
Not consumers of medicine
Exclusion criteria:
Having any injuries or pain
Inability to perform tests
Non-adherence to recommendations
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Intervention groups
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Consuming beetroot juice supplement (140 ml) or placebo (140 ml of nitrate-depleted beetroot juice) 120 minutes before exercise sessions
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Main outcome variables
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Number of throws; Heart rate immediately after SJFT; Heart rate one minute after SJFT; SJFT index; Rate of perceived exertion
General information
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Reason for update
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Adding some secondary variables to evaluate possible mechanisms; Adding subjects number to enhance statistical analysis power; Using nitrate-depleted beetroot juice as a placebo to enhancing blinding effect.
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Acronym
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IRCT registration information
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IRCT registration number:
IRCT20231004059615N3
Registration date:
2025-05-22, 1404/03/01
Registration timing:
registered_while_recruiting
Last update:
2026-04-07, 1405/01/18
Update count:
1
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Registration date
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2025-05-22, 1404/03/01
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Registrant information
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Recruitment status
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Recruitment complete
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Funding source
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Expected recruitment start date
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2025-05-22, 1404/03/01
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Expected recruitment end date
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2025-05-31, 1404/03/10
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Actual recruitment start date
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empty
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Actual recruitment end date
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empty
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Trial completion date
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empty
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Scientific title
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Acute effects of beetroot juice supplementation on the Special Judo Fitness Test performance in judokas: a randomized double-blinded crossover trial
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Public title
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Acute effects of beetroot juice supplementation on judo performance
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Purpose
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Other
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Inclusion/Exclusion criteria
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Inclusion criteria:
Having at least a Purple Belt in Judo
Free from neuromuscular and musculoskeletal disorders
Non-smokers
Non-alcoholic
Not consumers of medicine
Exclusion criteria:
Having any injuries or pain
Inability to perform tests
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Age
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From 20 years old to 30 years old
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Gender
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Both
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Phase
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3
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Groups that have been masked
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- Participant
- Investigator
- Outcome assessor
- Data analyser
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Sample size
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Target sample size:
34
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Randomization (investigator's opinion)
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Randomized
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Randomization description
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The names of the subjects will be entered in one column of Excel; in another column, a number will be randomly assigned to each subject using the RAND function (=RAND()); then, the numbers will be sorted from smallest to largest; 50% of the subjects (from rows 1 to 8) will receive the supplement and the other 50% (from rows 9 to 16) will receive the placebo. In the second experimental session, the subjects will be switched (subjects who received the supplement in the first session will receive the placebo in the second session and vice versa).
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Blinding (investigator's opinion)
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Double blinded
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Blinding description
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The order of beetroot juice supplement or placebo intake will be determined randomly by a person outside the study, and participants and researchers will not be informed of it until after data analysis. Also, subjects will receive the supplement and placebo in an opaque container with a similar appearance. In addition, the color and taste of the placebo will be similar to the beetroot juice through the addition of food coloring and flavoring.
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Placebo
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Used
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Assignment
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Crossover
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Other design features
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Ethics committees
1
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Ethics committee
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Approval date
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2025-05-14, 1404/02/24
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Ethics committee reference number
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202505-03
Health conditions studied
1
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Description of health condition studied
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Improve exercise performance
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ICD-10 code
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ICD-10 code description
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Primary outcomes
1
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Description
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SJFT index
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Timepoint
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َAfter SJFT
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Method of measurement
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Using the following formula: SJFT index = HR0 + HR1 / total number of throws
Secondary outcomes
1
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Description
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Rate of perceived exertion
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Timepoint
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Following SJFT
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Method of measurement
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Using the Borg scale
2
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Description
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Number of throws
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Timepoint
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During the SJFT
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Method of measurement
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Counting the number
3
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Description
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Heart rate
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Timepoint
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Immediately at the end of SJFT and 1 minute after SJFT
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Method of measurement
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Using a Polar heart rate monitor
4
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Description
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Plasma nitrate concentration
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Timepoint
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At baseline, pre-test, and post-test (5 minutes after exercise)
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Method of measurement
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By high‑performance liquid chromatography method (ENO‑20; EiCom, Kyoto, Japan)
5
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Description
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Plasma nitrite concentration
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Timepoint
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At baseline, pre-test, and post-test (5 minutes after exercise)
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Method of measurement
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By high‑performance liquid chromatography method (ENO‑20; EiCom, Kyoto, Japan)
6
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Description
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Plasmalactate
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Timepoint
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At baseline, pre-test, and post-test (5 minutes after exercise)
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Method of measurement
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Using a lactate ELISA kit
7
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Description
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Muscle oxygenation
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Timepoint
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During the SJFT
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Method of measurement
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Near-infrared spectroscopy
Intervention groups
1
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Description
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Intervention group: Beetroot juice supplement (140 ml, containing approximately 12.8 mmol nitrate) in opaque bottles will be consumed 2 hours before exercise. Commercial beetroot juice supplement (BEET It Sport®; James White Drinks Ltd., Ipswich, UK) will be used in this study.
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Category
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Rehabilitation
2
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Description
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Placebo (140 ml) will be consumed 2 hours before exercise in opaque bottles. Commercial nitrate-depleted beetroot juice supplement (NO₃⁻-depleted BJ, Beet It Sport®, James White Drinks Ltd., UK) will be used in this study.
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Category
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Rehabilitation
1
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Sponsor
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Grant name
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Grant code / Reference number
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Is the source of funding the same sponsor organization/entity?
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Yes
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Title of funding source
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INTERNATIONAL SCIENCE AND TECHNOLOGY UNIVERSITY
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Proportion provided by this source
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100
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Public or private sector
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Private
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Domestic or foreign origin
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Foreign
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Category of foreign source of funding
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Sponsor: country of origin
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Country of origin
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Ir
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Type of organization providing the funding
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Persons
Sharing plan
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Deidentified Individual Participant Data Set (IPD)
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Yes - There is a plan to make this available
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Study Protocol
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Yes - There is a plan to make this available
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Statistical Analysis Plan
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Undecided - It is not yet known if there will be a plan to make this available
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Informed Consent Form
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Undecided - It is not yet known if there will be a plan to make this available
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Clinical Study Report
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Not applicable
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Analytic Code
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Not applicable
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Data Dictionary
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Not applicable
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Title and more details about the data/document
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All data collected during the study will be shareable after de-identifying the subjects.
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When the data will become available and for how long
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The data will be published after the extracted articles are accepted.
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To whom data/document is available
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All people
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Under which criteria data/document could be used
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All data collected during the study will be shareable after de-identifying the subjects. The requester will only be permitted to use the data for meta-analysis reviews.
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From where data/document is obtainable
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Corresponding author:
Davar Khodadadi, Faculty of Physical Education and Sports Sciences, Islamic Azad University Central Tehran Branch, Tehran, Iran
Email: davar.khodadadi@yahoo.com
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What processes are involved for a request to access data/document
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Sending an email request to the corresponding author:
Davar Khodadadi
Email: davar.khodadadi@yahoo.com
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Comments
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