Muscle Injury Return To Play Design in Football; Effects of Backward Design Versus Forward Design . A Randomized Controlled Trial
Phase: NA
Conditions: Muscle Injuries, Football Players
Sponsor: Universitat de les Illes Balears

Research Protocol: Clinical Trial
Project title:
`` Muscle injury RTP design in football; effects of backward design vs forward design . A 
randomized controlled trial.´´
Version NO 1, date 25/05/2025
Project promoter: Oscar Vicente Rodríguez
Main researcher: Oscar Vicente Rodríguez
Collaborating researchers: José María Villalón Alonso, Olga Velasco Roldán,  Carles Pedret 
Carballido
1

Index
1-Project Background and Justification
2-Study hypothesis
3-Objectives
4-Type of study
5-Material and methods
	

	
5.1-Scope of study
	
5.2-Definition of Study Subjects
	
5.3-Selection and removal of subject
	
5.4-Recruitment of participants
	
5.5-Allocation/randomization procedure
	
5.6-Justification of sample size
	
5.7-Primary and secondary variables
	
5.8-Description of the intervention
	
5.9-Timeline and expected completion date. Distribution of tasks among the members of the 	
	 	
research team.		

	
5.10-Statistical analysis plan
2

6-Ethical and legal aspects
	

	
6.1-Compliance with the following standards is required: Good Clinical Practice, the 	
	
	 	
Declaration of Helsinki, the Oviedo Convention, and Law 3/2018 of December 5, 2018, on 	
	 	
the protection of personal data and the guarantee of digital rights. Regulations on the 	
	
	 	
management of medical records must also be followed.	
	

	
6.2-Informed Consent Form (Annex 1 and 2)
	
6.3-Confidentiality of the information collected in the context of the study.
	
6.4-Handling of biological samples in accordance with Law 14/2007 and Royal Decree 		
	 	
1716/2011
	
6.5-Insurance policy or justification of absence for experimental studies
	
6.6-Commitment to publish results
7-Financial Report and Sources of Financing
8-Data Collection Notebook (Annex 3)
	
	
Annex 4: GAD-7 Scale
	
	
Annex 5: Protocol for measuring cortisol Elisa test
	
	
Annex 6: Oura Ring Sleep Quality Measurement Scale
	
	
Annex 7: BAMIC classification of muscle injuries
9-Bibliography
3

1-Project Background and Justification
"Return-to-play" (RTP) is an English term that corresponds to "return to competition" (1). It is 
important to understand that this return is a constant, dynamic, and personalized decision-making 
process (2). The main objective of RTP is not to predict the exact moment of an athlete's return; 
rather, it is to prevent new injuries. For this, adequate decision-making is necessary (3). There are 
several important steps in the process, including correct diagnosis, strict control of workloads, and 
intelligent management of modifiers intrinsic to the sport that can lead to anxiety and stress (4).
Muscle tissue is tremendously dynamic and vulnerable to injury, especially in sports (5), where it 
accounts for 31% of all injuries and 30% of re-injuries (6). Due to the wide range of muscle groups 
and the numerous factors that influence injury, recovery time for these injuries varies greatly, even 
for injuries that occur in the same muscle or muscle group (7).
Muscle injuries are inherently associated with sports exposure (8), representing a very high 
percentage (6). According to the latest scientific publications, little progress has been made in the 
study of RTP, and it may have even gone in the wrong direction (9-11). Currently, only a few 
studies (12, 13) adequately address RTP and focus on monitoring the process. Due to the lack of 
consensus on RTP design, several questions arise.
How are the pieces of the RTP puzzle organized and managed?(1)
 How are RTP processes evaluated today?
How should RTP be understood? Should it be understood statically, as a checklist, or as a constant 
decision-making process involving the player?(3)
As previously mentioned, the RTP process should not become a guessing game because it could 
cause anxiety (4) and stress for the player and their environment. The design and structure of the 
RTP process could significantly impact the success or failure of an athlete's recovery decision-
making process.
4

2-Study hypothesis
H0=The regression design (14, 15) of the RTP is the most appropriate since it positively influences 
the variables.
HA=The regressive RTP design is not the most appropriate, as it significantly influences the 
variables in a detrimental way. The progressive RTP design (16,17) is more appropriate because it 
significantly influences the variables in a beneficial way.
3-Objectives
	
	
Main objective: To evaluate the design of the RTP process for muscle injuries in sport.
	
Specific objectives:
	
 -Compare two RTP designs and evaluate how their design influences the player's anxiety 	
	 	
(4).
	
-Identify variables that may be altered, sleep quality and cortisol level (18), when choosing a 
	 	
regressive or progressive RTP design.	
	

	
-Establish direction in the design of the RTP process.
	
-Complete clinical guidelines (5) on muscle injuries in sports with a focus on return-to-play 	
	 	
(RTP) design.
4-Type of study
	This is a randomized, double-blind, single-center controlled clinical trial. There will be two 	 	
	 groups: a control group and an intervention group.
5

5-Material and methods
	
5.1-Scope of study
The study will be carried out in the work environment of the principal investigator and doctoral 
student at the University of the Balearic Islands (UIB) and Club Atlético de Madrid. The study will 
focus on the first and B teams, which are both based at the Ciudad Deportiva del Cerro del Espino 
in Majadahonda, Madrid. The study will be included in the principal investigator's doctoral thesis.
	
5.2-Definition of Study Subjects
The study subjects will be all players from the first team or team B who suffer a muscle injury 
diagnosed by MRI. At the time of injury, they will be randomly assigned to either the control group 
(following a regressive RTP design) or the intervention group (following a progressive RTP design). 
Masking will be double-blind.
	
5.3-Selection and removal of subject
Male soccer players diagnosed with a muscle injury via magnetic resonance imaging (MRI) during 
the three-year study period will be included in the trial. They will all belong to the same club and be 
between 18 and 40 years old.
The study will exclude muscle injuries that do not cause players to miss training or competitions. 
Also excluded are cases in which patients voluntarily decide not to participate in the study or 
abandon the return-to-play (RTP) process due to transfers or other exceptional causes.
5.4-Recruitment of participants
Since they are all players from the same club and suffer muscle injuries, they will be included in 
the control and intervention groups throughout the three-year trial period. The following section 
will explain that the sampling technique is consecutive and that subjects can participate in the study 
several times as long as they have a muscle injury diagnosed by resonance. Relapses of the same 
injury or injuries in the same or different muscle groups will also be included in the sample. Dr. 
6

José María Villalón Alonso, the head of the club's medical service and collaborating researcher, will 
be in charge of recruiting the participants. After the diagnostic test (MRI) is performed and the 
diagnosis and prognosis are established, the participants will be handed over to the recovery 
specialists, who will design the RTP. The specialists and the participants (players) will be blinded in 
the same way.
5.5-Allocation/randomization procedure
Assignment to the control and intervention groups will be done in a simple, randomized manner. 
Subjects with muscle injuries have the same 50% probability of being assigned to the control group 
or the intervention group, regardless of previous assignments.
5.6-Justification of sample size
We will carry out a type of consecutive sampling based on the average probability that a soccer 
player will suffer a muscular injury. This means that each player will suffer an average of 0.6 
muscular injuries per season (7). In a team of 25 players, this averages to 15 muscular injuries per 
season. By contrasting this data with the club's database, we can verify the accuracy of this 
estimate. According to this statistical data, the population from which we will extract the sample 
will be the total number of muscle injuries suffered by the two teams of Club Atlético Madrid over 
three years, that is.
0.6 (injuries) x 50 (players) x 3 years = 90 muscle injuries. Using the Grammo sample calculator 
with a relative error of 5% and a 95% confidence interval, we will calculate the necessary sample 
size for the sample to be representative, which will be N = 74.
7

5.7-Primary and secondary variables
5.8-Description of the intervention
Subjects with muscle injuries assigned to the control group will follow a regressive return-to-play 
(RTP) design, while those assigned to the intervention group will follow a progressive RTP 
program. The independent (secondary) variables will be recorded in the database after diagnosis 
with an MRI. Subsequently, the dependent (main) variables will be measured and recorded at the 
beginning, middle, and end of the RTP period. The following scheme illustrates the dynamics of the 
clinical trial.
8
Primary Variables
TYPE
MEASUREMENT TOOL
Player anxiety (4)
(Qualitative ordinal) 4 categories 
Mn/Mi/Mo/S, codificada en 
1/2/3/4
GAD-7 Scale (19) Protocol
Sleep quality (20)
(Qualitative ordinal) 4 categories 
P/A/B/O, codify in 1/2/3/4
Oura Ring, (21) Protocol
Stress/Cortisol (18) 
(Quantitative continue)  in ng/mL
Kit Cortisol Elisa (22) Protocol
Secondary Variables
TYPE
TYPE
Age
(Quantitative discrete)
Date of birth
Tissue involved(5)
(Qualitative nominal) 3 categories 
MFJ/MTJ/T, codify 1/2/3
MRI
Previous injuries to the same 
muscle.  (23)
(Qualitative nominal) 
dichotomous: Yes/Not, codify 0/1
Clinical History
Estimated Sports Absence 
Forecast (24)
(Quantitative discrete) in weeks
MRI Inform(24)

5.9-Timeline and expected completion date. Distribution of tasks among the members of the 
	 research team.	

 
-05/2025 to 08/2025 Task 1 Literature review, design (sample size calculation, protocols, 	
	
intervention/control group and randomization) following CONSORT statement (25), 	
	
	
approval by the Ethics Committee and registration of the clinical trial.
	
-08/2025 to 09/2025 Task 2 Collection and preparation of the material; questionnaires, 	 	
	
cortisol salivary kit, Oura Ring, creation of the database by categorizing and coding the 	 	
	
variables for optimal operation and registration.
	
-09/2025 Task 3 Start the trial, recruitment with consecutive sampling (muscle injury 	
	
	
episode), MRI, randomization, registration and measurement of variables.
9

	
-03/2027 Task 4 It is estimated that half of the necessary sample size has been reached: 	 	
	
approximately 37 subjects with muscle injury. The first statistical analysis will be carried out 
	
to observe preliminary results.
	
-09/2028 Task 5 After three years it is expected to have reached the N=74 size necessary for 
	
the sample to be representative.
	
-09/2028-12/2028 Task 6 Complete statistical analysis.
	
-12/2028-02/2029 Task 7 Writing the manuscript with the results obtained.
	
-02/2029-05/2029 Task 8 Submission to journal, corrections by reviewers and publication.
	
-05/2029-06/2029 Task 9 Presentation of results at an international congress.
	

10
Quarterly schedule
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Task 1
Task 2
Task 3
Task 4
Task 5
Task 6
Task 7
Task 8
Task 9
Color code researcher
Only main researcher
Principal +Collaborating 
researchers

5.10- Statistical analysis plan
-Phase 1: Levene's test to test the equality of variances between control and intervention groups.
-Phase 2: Student's t-test to determine whether there is a significant difference between the means 
of the control and intervention groups and to establish the H0 or HA as true.
-Phase 3: Perform a bivariate study between the dependent variable anxiety and the independent 
variable estimated prognosis, through Pearson's correlation coefficient.
-Phase 4: Conduct a multivariate study through multiple regression between the dependent 
variable sleep quality and the independent variables age, type of affected tissue and the variable 
cortisol level.
-Phase 5: To perform a multivariate study through a simple linear regression between the 
dependent variable anxiety and the independent variable previous injuries in the same musculature.
6-Ethical and legal aspects
6.1-The investigator must comply with the Good Clinical Practice Standards, the 
Declaration of Helsinki, the Oviedo Convention, and the December 5, 2018, Law 3/2018 on the 
protection of personal data and the guarantee of digital rights, as well as the regulations for 
managing clinical histories.
The investigator undertakes to comply with the aforementioned rules throughout the development 
of the research protocol, as well as in the presentation to this ethics committee, for which the 
investigator has obtained a Good Clinical Practice (GCP) certificate. The collaborating investigators 
also have this GCP certificate.
11

6.2-Informed Consent Form (Annex 1 and 2)
Both the patient information sheet and the informed consent form are attached in Annexes 1 and 	
	 2.	
	

6.3-Confidentiality of the information collected in the context of the study. 
Data Controller: Óscar Vicente Rodríguez
TLF: 699 874 059
Email: oscarvicente90@gmail.com
Purpose of data collection: Clinical and epidemiological research.
Maximum period of data retention: The data will be kept for four years (three years for the duration 
of the study and one extra year for future research).
Processing, communicating, and transferring the personal data of all participating subjects will 
comply with the provisions of Organic Law 3/2018 of December 5 on the protection of personal 
data and the guarantee of digital rights.
In accordance with the aforementioned legislation, you may exercise your rights of access, 
rectification, deletion, opposition, and limitation of data processing. You may also transfer your data 
to an authorized third party (data portability). For more information, please contact the principal 
investigator responsible for processing at oscarvicente90@gmail.com or at C/Moreno Torroba 10, 
1o B, CP. 28220 Majadahonda, Madrid.
Your data will be computerized and incorporated into an automated personal data system that 
complies with all security measures for restricted access, as described in this document.
To guarantee the confidentiality of the obtained information:
Your data and the sample will be identified by a code, and only the study physician and their 
collaborators will be able to relate this data to you and your medical history. Therefore, your 
identity will not be disclosed to anyone except in case of medical emergency or legal or 
administrative requirement.
12

Only the essential data necessary for the study will be transmitted to third parties and other 
countries. In no case will the data contain information that can directly identify you, such as your 
name, initials, address, or social security number. If this transfer occurs, it will be for the 
aforementioned study purposes and will guarantee confidentiality with at least the level of 
protection guaranteed by the legislation in force in our country.
Access to your personal information will be restricted to the study physiotherapist, collaborators, 
health authorities, the Balearic Islands Research Ethics Committee, and authorized personnel when 
required to verify the study's data and procedures, always maintaining confidentiality in accordance 
with current legislation.
You may contact the Spanish Data Protection Agency with any claims related to the processing of 
your personal data. 
6.4-Handling of biological samples in accordance with Law 14/2007 and Royal Decree 	 	
	 	
1716/2011
Saliva samples to determine cortisol levels will be collected at the Ciudad Deportiva Atlético de 
Madrid clinic on three occasions: at the beginning of the RTP, after the magnetic resonance 
diagnosis, in the middle of the established prognosis, and the day before the end of the RTP. The 
analysis will be performed at the same clinic, where, at the end of the cortisol measurement, the 
saliva will be discarded and only the recorded cortisol value will be kept.
Any risks associated with the procedure used to collect these samples are covered by the study 
insurance.
The samples will be coded and treated confidentially throughout this study. A code will be used to 
link the samples to you, and only the investigator and his staff will be able to decipher it to preserve 
your anonymity.
If additional data or samples are needed, your physiotherapist will contact you again to request your 
cooperation.
You will be informed of the reasons, and your consent will be requested again if necessary.
13

You will not receive any financial benefits from donating samples or transferring data, nor will you 
be entitled to commercial benefits from discoveries resulting from the research.
The samples will be analyzed at the Ciudad Deportiva Atlético de Madrid laboratory and stored for 
four years in case additional analyses related to the study's objectives are necessary. The person 
responsible for the samples will be the study promoter during this process.
At the end of the investigation, your sample may be destroyed.
-Destroyed
-Anonymized (i.e., the link between the sample and you will be completely destroyed so that neither 
the researcher nor any other team member will be able to identify who the sample belongs to again).
-Incorporated into a collection managed by researcher Óscar Vicente Rodríguez at Ciudad 
Deportiva Atlético de Madrid for continued use in the "Stress and Muscle Injury" study. - Stored in 
the biobank.
It may be stored in the Ciudad Deportiva Atlético de Madrid biobank for use in other research, 
possibly unrelated to the initial study for which consent was given. The biobank may transfer 
samples for authorized projects, possibly abroad, with prior favorable opinions from the scientific 
and biobank ethics committees. You may contact the biobank to obtain information on the projects 
in which your samples have been used.
6.5-Insurance policy or justification of absence for experimental studies
Mr. Óscar Vicente Rodríguez is the principal investigator with D.N.I. No. 35572548N, and member 
no. 1224, is registered in the Collective Policy of Professional Civil Responsibility, to which the 
Official College of Physiotherapists of the Balearic Islands adheres, with policy number 531000009 
from A.M.A. (Agrupación Mutual Aseguradora — La Mutua de los Profesionales Sanitarios). 
Annex 3.
14

6.6-Commitment to publish results
The principal investigator is committed to publishing the results, regardless of their nature, since 
there is no conflict of interest. The present trial will be part of the principal investigator's (doctoral 
student) thesis. Therefore, this fact guarantees the publication of the results, which will improve the 
design of the RTP process.
7-Financial Report and Sources of Financing
The project has no private funding other than that provided by the main researcher, Oscar Vicente 
Rodríguez, as explained in the table above. The MRI and radiological report expenses are free for 
the club due to the nature of the entity itself, without any conflict of interest. The same happens 
with the team of statisticians that can be used for the analysis of results, which are part of the UIB, 
and collaborate with doctoral theses, and therefore works that are included in them as will be this 
essay. In relation to the CEIm of the Balearic Islands, this trial will be exempt from fees, (presented 
in the documentation) as it is part of studies of the Doctoral School of the UIB.
15
Resources
€/ at 3 years
Staff
Statistical analysis team University of the 
Balearic Islands
0 €
Radiologist MRI report (Free to club)
0 €
Specific resources
Kit Elisa Cortisol Saliva (96 tests)  3 x 345.15€
1035.45€
MRI radiological tests (Free for club)
0 €
Ethics Committee of the CEIm, University of 
the Balearic Islands fee exempt
0 €
Devices
Oura Ring (Quality of sleep) 2 x 400€.
800 €
The cost of the data logging tablet and GAD-7 is 2 
x 700€.
1400 €
TOTAL TO BE COVERED BY THE MAIN 
RESEARCHER
3235.45€

8-Data Collection Notebook (Annex 3)
The type of variables, their coding and measurement tools are explained in the tables in section 
5.7-Main and secondary variables. The data collection notebook is attached as Annex 3. The GAD-7 
anxiety measurement scale (19) is attached as Annex 4, the Cortisol measurement protocol with the 
Elisa test (22) Annex 5, the sleep quality measurement scale (21) Annex 6, and as for the estimated 
prognosis (radiological report) the classification of muscular lesions (24) is attached as Annex 7.
16

Annex 1
PATIENT INFORMATION SHEET FOR THE CONDUCT OF CLINICAL TRIALS 
(Version No. 1, May 25, 2025) 
Study title:```Muscle injury RTP design in football; effects of backward design vs forward 
design . A randomized controlled trial.'' 
Protocol code: 
Sponsor: Óscar Vicente Rodríguez 
Principal Investigator: Óscar Vicente Rodríguez 
Position, unit, center: Physiotherapist Club Atlético de Madrid 
Telephone: 699 874 059 
E-mail: oscarvicente90@gmail.com 
Introduction 
We are writing to inform you about a study in which you are invited to participate. The 
study has been approved by the Balearic Islands Drug Research Ethics Committee in 
accordance with current legislation and will be conducted according to the principles 
outlined in the Helsinki Declaration and the standards of good clinical practice. 
Our only intention is for you to receive sufficient and accurate information so that you can 
decide whether or not to participate in this study. Please read this information sheet 
carefully, and we will clarify any doubts you may have after the explanation. You may also 
consult the people you deem appropriate. If you have any questions, please contact 
Óscar Vicente Rodríguez. 
General description 
This clinical trial aims to evaluate the design of the return-to-play (RTP) process for 
muscle injuries. We will also attempt to establish causal relationships between variables. 
 To this end, a review of the literature was conducted and two models were identified. The 
most widely used model in sports, which aims to predict RTP time in a regressive manner 
by establishing clear, specific objectives based on the hypothetical discharge date 
(hereafter referred to as the control group). 
17

The other working model, which is less popular, is one in which the objectives are set 
according to evolution, progressively and without being so inflexible. This model will be 
called the intervention group. 
Once patients are diagnosed with a muscle injury via magnetic resonance imaging, they 
will be randomly assigned to the control or intervention group. Masking will be double-
blind, meaning neither the patient nor the principal investigator will know which RTP 
design has been implemented.  
During the RTP process, the following independent variables will be recorded at the 
beginning: age, type of tissue involved, previous injuries to the same muscle group, and 
estimated prognosis in weeks. Then, the dependent variables—cortisol, sleep quality, and 
anxiety—will be measured at three points in the RTP process: the beginning, middle, and 
end. These measurements will then be recorded in the database. 
The required sample size is N = 74. 
Alternative treatments 
Both regressive and progressive RTP designs are generally used within an athlete's 
recovery. 
The principal investigator of the study, Physiotherapist Oscar Vicente Rodriguez will give 
you more information if you wish.  
Other relevant information 
If any new information concerning the study's designs that could affect your willingness 
to participate is discovered during your participation, your physician will communicate it 
to you as soon as possible. 
If you withdraw your consent to participate in the study, no new data will be added to the 
database, and you may request that all identifiable samples previously retained be 
destroyed to prevent further analysis. 
Study managers may continue to use the information collected about you up to that 
point, unless you object. 
You should also be aware that you may be withdrawn from the study if the study leaders 
deem it appropriate for safety reasons or due to an adverse event, or if they determine 
that you are not complying with established procedures. In either case, you will receive an 
adequate explanation for your withdrawal. 
If you are withdrawn from the study for any of these reasons, your physician will prescribe 
treatment for your condition. 
Al firmar la hoja de consentimiento adjunta, se compromete a cumplir con los 
procedimientos del estudio que se le han expuesto.  
18

Benefits and risks of participating in the study 
The benefits obtained from their participation in the study include improved RTP designs 
that are better adjusted to specific muscle injuries and beneficial interactions with 
dependent variables such as cortisol, sleep quality, and anxiety. 
The risks associated with participation are minimal and do not increase with respect to 
the general RTP process design. 
Saliva samples will be stored during the analysis process and then destroyed; the results 
will be kept for three years. 
Insurance 
The study's promoter, member number 1224, has a Collective Professional Liability 
insurance policy with the Official College of Physiotherapists of the Balearic Islands. The 
policy number is 531000009 with the company Agrupación Mutual Aseguradora — La 
Mutua de los Profesionales Sanitarios. It complies with current legislation and covers all 
damages that may occur in relation to participation in the study. 
Confidentiality  
Responsible for treatment: Óscar Vicente Rodríguez 
TLF: 699 874 059 
Email: oscarvicente90@gmail.com 
Purpose of data collection: Clinical and epidemiological research. 
Maximum period of data retention: The data will be kept for four years (three years for the 
duration of the study and one extra year for future research). 
Processing, communicating, and transferring the personal data of all participating 
subjects will comply with the provisions of Organic Law 3/2018 of December 5 on the 
protection of personal data and the guarantee of digital rights. 
In accordance with this legislation, you may exercise your rights of access, rectification, 
deletion, opposition, and limitation of data processing. You may also transfer your data to 
an authorized third party (data portability). For more information, please contact the 
principal investigator responsible for processing at oscarvicente90@gmail.com or at C/
Moreno Torroba 10, 1º B, CP. 28220 Majadahonda, Madrid. 
Your data will be processed electronically and incorporated into an automated personal 
data system that complies with all security measures for restricted access, for the 
purpose described in this document. 
To guarantee the confidentiality of the obtained information: 
Your data and the sample will be identified by a code, and only the study physician and 
collaborators will be able to relate such data to you and your clinical history. 
19

Therefore, your identity will not be disclosed to anyone except in the event of a medical 
emergency or if required by health administration or legal authorities. 
Only the data necessary to conduct the study will be shared with third parties and other 
countries. In no case will the data contain information that can directly identify you, such 
as your name, initials, address, or social security number. If this transfer occurs, it will be 
for the aforementioned study purposes and to ensure confidentiality with at least the level 
of protection guaranteed by the legislation in force in our country. 
Access to your personal information will be restricted to the study physiotherapist, 
collaborators, health authorities, the Balearic Islands Research Ethics Committee, and 
authorized personnel when required to verify the study's data and procedures, always 
maintaining confidentiality in accordance with current legislation. 
You may contact the Spanish Data Protection Agency with any claims related to the 
processing of your personal data. 
Financial compensation 
Participation in the study is free of charge, and you will be reimbursed for any additional 
expenses, such as meals and travel. 
Your physiotherapist will not receive any financial compensation for your participation in 
the study, and he or she has declared no conflict of interest. 
Voluntary participation 
You should know that your participation in this study is voluntary. You may choose not to 
participate, or you may change your mind and withdraw your consent at any time without 
providing an explanation. You may also request the destruction of the sample without 
affecting your relationship with your doctor or your treatment. 
If you revoke your consent, no new data will be collected or new analyses performed on 
the sample. However, this revocation will not affect the research carried out up to this 
point. 
Collection of biological samples 
Saliva samples to determine cortisol levels will be collected at the Ciudad Deportiva 
Atlético de Madrid clinic on three occasions: at the beginning of the RTP, after the 
magnetic resonance diagnosis, halfway through the established prognosis, and the day 
before the RTP ends. The analysis will be performed at the same clinic, where, at the end 
of the cortisol measurement, the saliva will be discarded and only the recorded cortisol 
value will be kept. 
Any risks associated with the procedure used to collect these samples are covered by the 
study insurance. 
The samples will be coded and treated confidentially throughout this study. Only the 
investigator and his staff will be able to link the code to your identity. 
If additional data or samples are needed, your physical therapist will contact you to 
request your cooperation. You will be informed of the reasons and asked for your consent 
again, if necessary.No percibirá ningún beneficio económico por la donación de las 
20

muestras y la cesión de los datos aportados, ni tendrá derecho sobre posibles beneficios 
Commercial discoveries may result from the research. 
The samples will be analyzed in the Ciudad Deportiva Atlético de Madrid laboratory and 
stored for four years in case additional analyses related to the study's objectives are 
necessary. The person responsible for the samples will be the study promoter during this 
process. 
At the end of the research period, your sample may be: 
- Destroyed 
- Anonymized (i.e., the link between the sample and you will be completely destroyed so 
that neither the researcher nor any other team member will be able to identify to whom 
your sample belongs again). 
-Incorporated into a collection managed by researcher Óscar Vicente Rodríguez at the 
Ciudad Deportiva Atlético de Madrid so that it can continue to be used in the "Stress and 
Muscle Injury" study and line of research. ́  
The samples are stored in the Ciudad Deportiva Atlético de Madrid biobank for use in 
other research projects, which may be unrelated to the initial study for which consent was 
given. The biobank may provide the samples to authorized projects, possibly abroad, with 
prior approval from the scientific and ethics committees. You may contact the biobank to 
obtain information on projects in which your samples were used. 
Acknowledgment 
No matter what you decide, the sponsor and research team would like to thank you for 
your time and attention. By participating, you are contributing to a better understanding 
and care of your disease, which may benefit many people in the future. 
21

Annex 2
INFORMED CONSENT FOR THE CONDUCT OF CLINICAL TRIALS(Version No. 1, 
May 25, 2025) 
Study Title: "Muscle Injury RTP Design in Football: Effects of Backward Design vs. 
Forward Design." A Randomized Controlled Trial." PROMOTER CODE: 
Promoter Code: Promoter: Óscar Vicente Rodríguez 
Principal Investigator: Óscar Vicente Rodríguez, Physiotherapist, Tel: 699 874 059, Email: 
oscarvicente90@gmail.com 
Center: Ciudad Deportiva Atlético Madrid 
I, (name and surname), have read the information sheet given to me. 
I was able to ask questions about the study. 
I have received sufficient information about the study. I have spoken with Óscar Vicente 
Rodríguez. I understand that my participation is voluntary. 
I understand that I can withdraw from the study and request the destruction of my saliva 
cortisol, sleep monitoring, and anxiety state (GAD-7) results as long as they have not 
been anonymized. 
-Without having to explain myself. 
- Without impacting my medical care. 
 
I understand that if I withdraw from the study, the results obtained up to that point can be 
used for cortisol in saliva, sleep monitoring, and anxiety state results (GAD-7). However, 
no new analyses will be carried out on my sample as long as it has not been anonymized.  
If the research results provide data that may interest me or my family members, I would 
like to be informed.  
I do not want to be informed, but I agree that my physician may contact my family 
members if the results affect them.  
I understand that I have the rights of access, rectification, deletion, opposition, and 
limitation of data processing. I also have the right to data portability, which allows me to 
transfer my data to an authorized third party. These rights are in accordance with the 
provisions of Organic Law 3/2018 of December 5 on the protection of personal data and 
the guarantee of digital rights. 
I freely give my consent to participate in the study and agree to the access and use of my 
data under the conditions detailed in the patient information sheet. 
22

At the end of the investigation, mark my sample with an X. 
 
0 Destroyed 
 
Anonymized: 
It will be incorporated into a collection for which Óscar Vicente Rodríguez is responsible. 
The collection is located at Ciudad Deportiva Atlético de Madrid and will continue to be 
used in the study of "Stress and Muscle Injury." Stored in the Ciudad Deportiva Atlético 
de Madrid biobank in order to be used in other research, possibly unrelated to the initial 
study for which I consented. 
It may be stored in the Ciudad Deportiva Atlético de Madrid biobank for use in other 
research, possibly unrelated to the initial study for which I consented.
Patient´s signature:   
 
 
 
 
Researchet´s signature:  
 
Name: Date   
 
 
 
 
 
Name: Date
23

Annex 3
DATA COLLECTION NOTEBOOK 
ID Patient
Age
Tissue 
involved
Previous 
injuries
Estimated 
forecast
Anxiety 
Average 3 
measures
Cortisol  
Average 3 
measures
Sleep 
Average 3 
measures
1M4L
30
2
1
3
Start   2 
Half   1 
Final    2
Start   3 
Half   2 
Final    4
Start   3 
Half   2 
Final    4
24

Annex 4 (19)
25

Annex 5 (22)
26

27

Annex 6 (21)
The Oura Ring's validated sleep quality scale. 

28

Annex 6 (24)
BAMIC muscle injury classification 
29

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