Investigating the effect of caffeine, beetroot juice, and their combination on judo-specific performance in simulated conditions of the competition day in judo athletes
Design
A crossover, placebo-controlled, double-blind, randomized, phase 3 clinical trial on 35 judo athletes. The RAND function of Excel software will be used for randomization.
Settings and conduct
Each participant will participate in 4 experimental sessions (following BR, caffeine, caffeine plus BR, placebo), completing 7 trials in each session (4 min of randori plus Sargent test plus back strength test plus grip strength test plus SJFT plus cognitive function). The study will be double-blinded and will be conducted in Ankara, Türkiye.
Participants/Inclusion and exclusion criteria
Inclusion criteria: Must have at least a brown belt in judo; must not smoke; must not drink alcohol; must have a daily caffeine intake of less than 100 mg.
Exclusion criteria: Must have any injury or illness; must be taking any supplements or medications.
Intervention groups
1) Beetroot juice consumption (from 2 days before the test: 2 times a day, 70 ml each time)
2) Caffeine consumption (on the day of the test: 3 times, 1 hour before the test and after the completion of the second and fourth attempts, each time 2 mg/kg of body weight)
3) Beetroot juice + caffeine consumption (beetroot juice: from 2 days before the test: 2 times a day, 70 ml each time; caffeine: on the day of the test: 3 times, 1 hour before the test and after the completion of the second and fourth attempts, each time 2 mg/kg of body weight)
4) Placebo consumption (consumption of 140 ml of water with red food coloring instead of beetroot juice and a capsule containing cellulose instead of caffeine)
Main outcome variables
SJFT index، Cognitive function
General information
Reason for update
Acronym
IRCT registration information
IRCT registration number:IRCT20231004059615N5
Registration date:2025-07-18, 1404/04/27
Registration timing:prospective
Last update:2025-07-18, 1404/04/27
Update count:1
Registration date
2025-07-18, 1404/04/27
Registrant information
Name
Davar Khodadadi
Name of organization / entity
Country
Iran (Islamic Republic of)
Phone
+98 21 2263 3583
Email address
davar.khodadadi@yahoo.com
Recruitment status
Recruitment complete
Funding source
Expected recruitment start date
2025-07-23, 1404/05/01
Expected recruitment end date
2025-07-27, 1404/05/05
Actual recruitment start date
empty
Actual recruitment end date
empty
Trial completion date
empty
Scientific title
The effect of caffeine and beetroot juice supplementation on specific judo performance during simulated competition-day conditions in judo athletes
Public title
Effect of caffeine and beetroot juice supplementation on specific judo performance
Purpose
Other
Inclusion/Exclusion criteria
Inclusion criteria:
All male judokas between the ages of 18 and 25.
Have a training history of more than 5 years.
Have at least a brown belt in judo.
Do not smoke.
Do not drink alcohol.
Have a daily caffeine intake of less than 100 mg.
Exclusion criteria:
Have any illness or injury in the past 3 months
Take any medication or nutritional supplement in the past 3 months
Age
From 18 years old to 30 years old
Gender
Male
Phase
3
Groups that have been masked
Participant
Investigator
Data analyser
Sample size
Target sample size:
24
Randomization (investigator's opinion)
Randomized
Randomization description
The names of the subjects will be entered in one column of Excel; in another column, each subject will be randomly assigned a number using the RAND function (=RAND()); then, the numbers will be sorted from smallest to largest; 25% of the subjects will receive Intervention 1 (caffeine supplement), 25% of the subjects will receive Intervention 2 (beetroot juice supplement), 25% of the subjects will receive Intervention 3 (caffeine + beetroot juice), and the remaining 25% will receive placebo. In the second to fourth sessions of the experiment, the subjects will be switched (for example, subjects who received Intervention 1 in the first session will be randomly assigned to Intervention 2, 3, or placebo in the second session).
Blinding (investigator's opinion)
Double blinded
Blinding description
The order in which the beetroot juice supplement or placebo was administered will be determined by one outside the study and will not be disclosed to participants or researchers until after the data analysis. Participants will also receive the supplements and placebo in a capsule (caffeine) and a bottle (beetroot juice) that are opaque and look similar. In addition, the color and taste of the placebo will be simulated by adding food coloring and flavoring to the supplement.
Placebo
Used
Assignment
Crossover
Other design features
Secondary Ids
empty
Ethics committees
1
Ethics committee
Name of ethics committee
Ethics Committee of the International Science and Technology University
Street address
Tunahan Mah. Dumlupinar 30 Agustos Cad. No:2, Metromal Business F Blok Office
City
Ankara
Postal code
21,06824
Approval date
2025-07-03, 1404/04/12
Ethics committee reference number
202507-01
Health conditions studied
1
Description of health condition studied
Improve exercise performance
ICD-10 code
ICD-10 code description
Primary outcomes
1
Description
SJFT index
Timepoint
In the 7 stages after judo randori
Method of measurement
Using the following formula: SJFT index = HR0 + HR1 / total number of throws
2
Description
Cognitive function
Timepoint
In the 7 stages after judo randori
Method of measurement
Using the Stroop and Flanker tests
Secondary outcomes
1
Description
Number of throws
Timepoint
In the 7 stages after judo randori
Method of measurement
Counting the number
2
Description
Heart rate
Timepoint
In the 7 stages after judo randori, immediately at the end of SJFT and 1 minute after SJFT
Method of measurement
Using a Polar heart rate monitor
3
Description
Rate of perceived exertion
Timepoint
In the 7 stages after judo randori
Method of measurement
Using the Borg scale
4
Description
Lower body explosive power
Timepoint
In the 7 stages after judo randori
Method of measurement
Sargent Jump Test
5
Description
Muscular strength
Timepoint
In the 7 stages after judo randori
Method of measurement
Isometric strength testing device for back and hand muscles
6
Description
Blood lactate
Timepoint
In the 7 stages after judo randori
Method of measurement
Lactometer
Intervention groups
1
Description
Intervention group1: Beetroot juice supplement (BEET It Sport®; James White Drinks Ltd., Ipswich, UK); 2 days before the test: 2 servings, 70 ml each, containing approximately 6.4 mmol nitrate;1 day before the test: 2 servings, 70 ml each, containing approximately 6.4 mmol nitrate;Test day: 2 servings, 2 hours before the test and after the second randori, 70 ml, containing approximately 6.4 mmol nitrate.
Category
Other
2
Description
Intervention group 2: Caffeine supplement (Caffeine®, Olimp Laboratories, Poland); Test day: 3 servings, 1 hour before the test and after the second and fourth attempts, 2 mg/kg body weight each.
Category
Other
3
Description
Intervention group 3: Beetroot juice supplement (BEET It Sport®; James White Drinks Ltd., Ipswich, UK); 2 days before the test: 2 servings, each 70 ml, containing approximately 6.4 mmol nitrate; 1 day before the test: 2 servings, each 70 ml, containing approximately 6.4 mmol nitrate; Test day: 2 servings, 2 hours before the test and after the second attempt, 70 ml, containing approximately 6.4 mmol nitrate. Caffeine supplement (Caffeine®, Olimp Laboratories, Poland); Test day: 3 servings, 1 hour before the test and after the second and fourth attempts, 2 mg/kg body weight each
Category
Other
4
Description
Control group: Similar to the intervention condition, they will receive placebo (colored water instead of beetroot juice and a capsule containing cellulose instead of caffeine).
Category
Other
Recruitment centers
1
Recruitment center
Name of recruitment center
INTERNATIONAL SCIENCE AND TECHNOLOGY UNIVERSITY
Full name of responsible person
Heidar Sajedi
Street address
Tunahan Mah. Dumlupinar 30 Agustos Cad. No:2, Metromal Business F Blok Office
City
Ankara
Postal code
21,06824
Phone
+90 312 475 76 15
Email
heidar.sajedi@istu.edu.pl
Sponsors / Funding sources
1
Sponsor
Name of organization / entity
INTERNATIONAL SCIENCE AND TECHNOLOGY UNIVERSITY
Full name of responsible person
Erdal Dursun
Street address
Tunahan Mah., Dumlupinar 30 Agustos Cad. No. 2, Metromal Business F Blok Office
City
Ankara
Postal code
21,06824
Phone
+90 312 475 76 15
Email
heidar.sajedi@istu.edu.pl
Grant name
Grant code / Reference number
Is the source of funding the same sponsor organization/entity?
Yes
Title of funding source
INTERNATIONAL SCIENCE AND TECHNOLOGY UNIVERSITY
Proportion provided by this source
100
Public or private sector
Private
Domestic or foreign origin
Foreign
Category of foreign source of funding
Sponsor: country of origin
Country of origin
IR
Type of organization providing the funding
Persons
Person responsible for general inquiries
Contact
Name of organization / entity
Islamic Azad University
Full name of responsible person
Davar Khodadadi
Position
Assistant professor
Latest degree
Ph.D.
Other areas of specialty/work
Physiology
Street address
Faculty of Physical Education and Sports Sciences, Velayat University Complex, Shahid Sohani St., Sohank
City
Tehran
Province
Tehran
Postal code
1955847781
Phone
+98 21 2263 3583
Fax
Email
davar.khodadadi@yahoo.com
Person responsible for scientific inquiries
Contact
Name of organization / entity
Islamic Azad University
Full name of responsible person
Davar Khodadadi
Position
Assistant professor
Latest degree
Ph.D.
Other areas of specialty/work
Physiology
Street address
Faculty of Physical Education and Sports Sciences, Velayat University Complex, Shahid Sohani St., Sohank
City
Tehran
Province
Tehran
Postal code
1955847781
Phone
+98 21 2263 3583
Fax
Email
davar.khodadadi@yahoo.com
Person responsible for updating data
Contact
Name of organization / entity
Islamic Azad University
Full name of responsible person
Davar Khodadadi
Position
Assistant professor
Latest degree
Ph.D.
Other areas of specialty/work
Physiology
Street address
Faculty of Physical Education and Sports Sciences, Velayat University Complex, Shahid Sohani St., Sohank
City
Tehran
Province
Tehran
Postal code
1955847781
Phone
+98 21 2263 3583
Fax
Email
davar.khodadadi@yahoo.com
Sharing plan
Deidentified Individual Participant Data Set (IPD)
Yes - There is a plan to make this available
Study Protocol
Yes - There is a plan to make this available
Statistical Analysis Plan
Undecided - It is not yet known if there will be a plan to make this available
Informed Consent Form
Undecided - It is not yet known if there will be a plan to make this available
Clinical Study Report
Not applicable
Analytic Code
Not applicable
Data Dictionary
Not applicable
Title and more details about the data/document
All data collected during the study will be shareable after de-identifying the subjects.
When the data will become available and for how long
The data will be published after the extracted articles are accepted.
To whom data/document is available
All people
Under which criteria data/document could be used
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.
From where data/document is obtainable
Corresponding author: Davar Khodadadi, Faculty of Physical Education and Sports Sciences, Islamic Azad University Central Tehran Branch, Tehran, Iran Email: davar.khodadadi@yahoo.com
What processes are involved for a request to access data/document
Sending an email request to the corresponding author: Davar Khodadadi Email: davar.khodadadi@yahoo.com