Multidisciplinary training program for the promotion of physical activity and other healthy habits in adolescents: justification, design and methodology of PAP study

Overweight and obesity are one of the most important health problems worldwide. Physical inactivity is indicated as one of the most determining factors of overweight and obesity. The Self-Determination Theory points out the importance of motivation in the patterns related to physical activity. The aims of this study were to show the reasons for performing and the methods of a randomised controlled trial o evaluate the effectiveness of a multidisciplinary physical activity programme to promote physical activity levels in inactive school children and encourage healthy lifestyles, carried out under the Self-Determination Theory postulates. The present paper presents a RCT for adolescents of 1st and 2nd grades of Secondary Compulsory School. The multidisciplinary training program consists of two parts: the first part is cross-sectional, and the second part, the Physical Activity Program, is of a longitudinal nature. This project takes into account the socio-economic impact that a healthy lifestyle will generate, as well as its potential to apply the results and transfer them to the productive sector. This study is of great interest to the scientific community as it will provide relevant information on physical inactivity issues, sedentary lifestyle, generation of healthy habits and physical exercise.


Background
According to the World Health Organization (1) overweight and obesity are defined as an abnormal or excessive accumulation of fat that can be harmful to health, and they are one of the most important public health problems worldwide, generating biological and psychosocial disorders. Numerous studies worldwide (2) have developed interventions to promote healthy lifestyles in childhood and adolescence (3,4).
Among the determining factors of high levels of overweight and obesity in youth population is physical inactivity (PI). PI is defined as decrease in body movement that produces decreased energy expenditure (5) and seems to be one of the main triggers of overweight and obesity registered in the recent studies worldwide (6). The WHO (1) places the PI as the fourth risk factor for death, and it is the cause of 6% of the deaths registered annually in the world and the main cause of some diseases (breast and colon cancer, diabetes, or heart disease). At the National and European levels, respectively, both the Center for Sociological Research (7) and the EU point out in their report that 35% of adolescents between 9 and 17 years are insufficiently active and, that, as of age 15, only half of them perform physical activity (PA).
Studies that have analyzed the consequences of PI reveal childhood and adolescence as key stages to attenuate the effects of overweight and obesity (8). A growing body of literature, arising from the Self-Determination Theory (SDT; 9) has begun to note the influence of motivation in shaping PA patterns, contributing compelling evidence to support and understand the utility of motivation to increase PA (10). At the most basic level, SDT divides the types of motivations into intrinsic motivation (i.e., behavior as inherently enjoyable), extrinsic motivation (i.e., behavior as a means to an end), and amotivation (lack of motivation). Extrinsic motivations are further divided into categories on an underlying continuum reflecting the degree to which the source of the motivation is external (e.g., rewards/punishment) or internal (e.g., valuing its outcomes). The last great construct is amotivation, associated with behaviors that produce disorganized activity and associated with feelings of incompetence or frustration (9).
If continued PA can be consolidated as a habit, it will imply a series of benefits at the biological (11) and psychosocial level (12). Based on the above issues, this paper reports the reasons for and methods of a randomised controlled trial (RCT) to evaluate the effectiveness of a multidisciplinary Physical Activity Programme (PAP) to increase in inactive school children's PA levels and promote healthy lifestyles, developed following the SDT postulates.

Design of the multidisciplinary training program
The present paper is a RCT, corresponding to: Multidisciplinary Training Program for the Promotion of Physical Activity and Other Healthy Habits in Inactive Adolescents. The present paper is a RCT, corresponding to: Multidisciplinary Training Program for the Promotion of Physical Activity and Other Healthy Habits in Inactive Adolescents. The Trial registration: ClinicalTrials.gov ID: NCT03974607. Registered 19 August 2019 -Retrospectively registeres, https://cutt.ly/ger0Xbg. This research is intended for adolescents enrolled in 1 st and 2 nd grade of Secondary Compulsory School. The multidisciplinary training program consists of two parts: the first one is cross-sectional, and the second part is the randomised longitudinal. Each of these parts is subdivided into different phases (Figure 1). The first part is subdivided into three phases: contact with the school, recruitment of the participants, and evaluation of the participants. The PAP is subdivided into four phases: recruitment of the participant's school for PAP, selection of participants, evaluation of the participants, and training of periodization.
The study will be carried out following the ethical guidelines of the Declaration of Helsinki, and its 2013 modification, and approved by the Human Research Ethics Committee of the University of Extremadura. Sample selection will be random, inviting the schools that participate in the first part from participating second part: PAP. The order of the reserve schools will also be drawn to prepare a list to replace those institutions whose directors refuse to participate.
To minimize the risks during the development of the study, the contraindications of the protocols marked by each evaluation test will be discarded. If a problem arises during the study, participants will be referred for a medical evaluation and, if necessary, they will be removed from the study. The present investigation will contract a civil liability insurance that will cover the participants, the responsibility of the researcher and of any person involved in the study, provided that there is adequate adherence to the protocol.

Trial Status
The second part of the PAP, specificaly in the begining of phase 3 of the intervention programme. Therefore, it has been begun the contact with the participant's schools of the first part. Recruitment is expected to begin on September 31, 2019 and that it ends on October 18, 2019. Thereafter, the development of the PAP will begin.
Phase 1: Contact with the school A random selection of the different schools of the community of Extremadura will be made, up to a maximum of 23 schools. Also, 23 reserve schools will be randomly selected, in case the directors of the former school reject participation. This list will be arranged ordinally. The schools will be contacted, within a maximum period of one week, the research team and project technicians will contact the school directors via e-mail to confirm their interest in participating in the study. They will be given a period of fifteen days to respond. If they do not respond, they will be contacted by phone to present the project. If they do not accept participation in the study, we will proceed to contact the corresponding school of the reservation list, following the same procedure. If, on the contrary, they agree to participate, within a period of one week, visits to hand in the package of questionnaires will be programmed with the school director, and anthropometric and physical evaluation tests will be performed. To carry out these tests, the researchers will travel to the corresponding school to conduct the measurements. All measurements will be performed by the same research team, and each member will specialize in one test, to reduce possible measurement errors.
Phase 2: Recruitment of the participants Once the schools have been randomised, all the students of the 1 st and 2 nd Secondary Compulsory Education Schools that accept taking part in the study will be allowed to participate. All students who wish to participate must submit two authorizations, one signed by their parents or tutors, and the other signed by the participants themselves, accepting participation in the study. Thus, we will avoid those cases in which the parent or tutor accepts participation in the study, but the adolescent refuses. The following inclusion criteria will be established: collaboration of the school after the draw, students' age ranging from 12 to 14 years (1 st and 2 nd grade of Secondary Compulsory Education) and delivering the informed consent signed by a parent or guardian and the participant.
Phase 3: Evaluation of the participants.
The variables and instruments to be used for the collection of cross-sectional data during the first part of the study are shown below (Table 1).

Lifestyle variables
Self-reported PA level. The PA level will be assessed with the PA Questionnaire for Adolescents (PAQ-A) (13). This is a self-administered, 7-day recall instrument, with 9 items scored on a five-point scale. The PAQ-A provides a final composite activity score composed of the mean of the 9 items. This questionnaire has been shown to be valid and reliable (13,14). Extracurricular PA is assessed with the Finnish PA Index (15). It consists of 5 items concerning frequency and intensity of extracurricular PA and participation in organized sports. Using these five items, a PA index is calculated. adherence (4-7), and good adherence (8)(9)(10)(11)(12) to the MeD (18). Poor adherence is categorized as "Poor Diet" and average adherence and good adherence are categorized as "Average Diet" and "Optimal Diet".

Health-related fitness
Health-related fitness is assessed by field-based tests and self-reports using the ALPHA Fitness test battery (19). The extended version of the ALPHA health-related fitness test battery includes the following tests: (i) weight and height and body mass index (BMI: weight (kg)/ heigth 2 (cm)); (ii) skinfold thickness (triceps and subscapular) to assess body composition; (iii) waist circumference; (iv) neck circumference (not included in the ALPHA Fitness battery) to assess body composition, (vi) the 20-m shuttle run test to assess cardiorespiratory fitness; (ii) handgrip strength; and (iii) standing long jump to assess musculoskeletal fitness; and (iv) the 4 × 10 m shuttle run test to assess motor fitness.
Weight and Height. Weight is recorded to the nearest 0.1 kg using an electronic scale (model SECA 877) with participants dressed in lightweight clothing and without shoes.
Height is measured to the nearest 1 mm using a telescopic height-measuring instrument.
BMI was calculated as weight (kg)/height (m 2 ). Anthropometric measures are performed twice and the average is recorded.
Skinfold. Triceps and subscapular skinfold thickness are measured on the non-dominant side of the body with a Holtain caliper (range, 0 to 40 mm; precision, 0.2 mm). The triceps is raised in a vertical fold halfway between the acromion process and the superior head of the radius, on the back of the arm. The subscapular skinfold is measured about 20 mm below the inferior angle of the scapula and 45° to the lateral side of the body. It is performed according to Lohman's anthropometric standardization reference manual (20).
Triceps and subscapular skinfold thickness are measured twice, but not consecutively, and mean of the two measurements is used in the analyses. Percentage Body Fat (BF %) will be calculated from triceps and subscapular skinfold thicknesses, using the equations developed by Slaughter et al. (21).
Waist Circumference. Waist circumference is measured with a non-elastic tape measure (SECA 200; range, 0 to 150 cm; precision, 1 mm), at the level of the natural waist, on a horizontal plane, which is the narrowest part of the torso, as seen from the front. In some obese participants, it is difficult to identify the waist circumference; therefore, this measurement is performed in the midpoint between the superior iliac spine and the costal edge in the midaxillary line (22). The measurements are taken at the end of a normal expiration, without the tape compressing the skin. The measurements are carried out twice, but not consecutively, and mean of the two measurements is used in the analyses. Takey, Tokio, Japan) will be used for this test. This dynamometer presents a high validity and reliability when compared with calibrated known weights (23). The participant squeezes gradually and continuously for at least two seconds, performing the test with the right and left hands in turn, and with the elbow in full extension as described elsewhere (23). The grip-span of the dynamometer is adjusted according to the hand size to determine the maximum handgrip strength using the equations specifically developed for children (24) and adolescents (25). The test is performed twice and the maximum score for each hand is recorded in kilograms. The sum of the scores achieved by left and right hands is used in the analysis.
Lower Limb Strength. Lower limb strength is evaluated with the standing long jump test.
The subject will place behind the initial line and feet shoulder width apart. The participant jumps as far forward as possible on a non-slip hard surface. The test is performed twice, and the best score is recorded in centimeters.  Second Part: PAP As we can see in the schedule (Figure 2), the PAP will consist of 4 phases: phase 1) recruitment of the school for PAP, phase 2) selection of participants, phase 3) evaluation of the participants and phase 4) PAP intervention Phase 4 will be subdivided into 4 subphases: P 1 ) pre-evaluation, P 2 ) development of PAP sessions, P 3 ) post-evaluation and P 4 ) retention measure. After confirming their participation, we will begin to recruit the participants through talks, meetings, posters, etc. If not enough participants are recruited to develop the out-ofschool PAP, the corresponding school of the reserve list will be used. If the school director accepts participation and sufficient participants are available, a new draw will be made among the participating schools to determine their assignation to the experimental group (EG) or control group (CG). There will be 2 EGs and 2 CGs. An initial meeting will be held with all the students interested in participating in the PAP outside school hours to set the days of the week and hours according to the participants' interests. All students who wish to participate must submit two authorizations, one signed by their parents or tutors, and the other signed by the participants themselves, accepting participation in the programme. The out-of-school PAP will be developed during 23 weeks, with a frequency of three weekly 60-minute sessions (see section: intervention program: training periodization)..

Phase 2: Selection of participants
A total of 120 participants will be enrolled in the out-of-school PAP. Based on previous intervention programs (29)(30)(31), the selection of the number of participants for the present investigation is considered to be be adequate. We believe that this sample size is feasible and realistic, based on studies of previous intervention programs. For statistical calculations, we will use IBM -SPSS software (version 23).
The estimates of the sample size and sampling power of the study are based on various observations of studies in which an intervention program based on PA and good habits was carried out (3,4,(29)(30)(31)(32)(33)(34).

Inclusion criteria
The intervention will also be implemented for adolescents who are overweight (BMI ≥ 25) and obese (BMI ≥ 30), as well as those who are active (time PA > 30 min > 3 days/week).
The criteria inclusion can be consulted in Table 2.
Excessive increase in levels of overweight and obesity in adolescence is associated with the risk of cardiovascular illness in the future (8,35), which reinforces the need to include this population within the study. In addition, despite the evidence that more active people show higher psychosocial levels (12,(36)(37)(38), it has not yet been determined whether increasing the PA levels of already active adolescents may strengthen or even increase psychosocial levels, although this supports the need to also include this group within the research.
This varied inclusion of sedentary, overweight, obese and active students will allow studying the effects produced by PA on the biological and psychosocial variables in both population groups. It has been shown that PA has a direct relationship with biological and psychosocial health, which is higher in active people than in sedentary people (11,12).
Therefore, it would be expected that both population groups would improve the parameters related to physical condition, body composition and psychosocial variables. Unwillingness either to complete the study requirements or to be randomised into con or training group. Not participating in a weight loss programme Provide informed consent by parents or legal guardians Participants must be capable and willing to provide consent, understand exclusion criteria and accept the randomised group assignment. Participants must attend at least 80% of the sessions.

Retention and adherence of the participants
Participants may abandon their participation in the study at any time but, to reduce participant dropout and maintain compliance with the program, several strategies will be used (i.e., allowing the participants to freely decide to perform some tasks over others or giving the adolescents responsibility).
All the sessions will be accompanied by the music selected by the participants and will be held in the gym of the corresponding school. Previously, it has been verified that the room in which the out-of-school PAP will take place has optimal ventilation and lighting conditions. Project technicians will carefully supervise each session and work with independent groups of no more than 30 participants to ensure good counselling.
To achieve greater adherence to and engagement in the program and based on the postulates of the SDT (9), methodological and motivational strategies designed with the interests and motivations of young people in mind will be developed to promote and consolidate the practice of out-of-school PA.

Phase 3: Evaluation of the participants
The out-of-school PAP will create collaborative learning so participants will achieve improvements at the social, psychological, physical and anthropometric level, in addition to increasing their PA levels. To support the development of this program, an implementation team will be designated to carry out the activities, which will vary according to the time and interest of the participants.

Evaluation of the CG
The control group will be selected in a targeted manner according to the availability of the school. The same package of questionnaires and anthropometric and physical tests will be given to them as to the EG. They will not be given any information about healthy habits nor will any physical training program be applied to them, so that they do not receive indications that could produce a variation of their habitual behavior.

Evaluation of the EG
In addition to the variables and instruments that will be used for the cross-sectional evaluation (consult the section of the variables and instruments of the cross-sectional part), in the PAP will be included (see Table 4 Relative Autonomy Index (RAI) is a composite score used to indicate the degree to which a person's exercise motivation is intrinsic or self-determined. The RAI is calculated by multiplying each Behavioural Regulation subscale score by a specific weight, and then summing the weighted scores. The maximum score for the RAI is +20, whereas the minimum is -24, with higher positive scores indicating more intrinsic motivation (10). For example, Item 1 is an External Regulation statement (-2 weight) "I exercise because people say I should." If the respondent chooses 2 (on a scale of 0-4), the score (2) is multiplied by the weight (-2), obtaining a score of -4 for this item.
Satisfaction with life. This aspect was evaluated with the Satisfaction With Life Scale (SWLS, (49)). The scale has 5 items rated on a 5-point Likert scale, ranging from 1 (Totally disagree) to 5 (totally agree). The present investigation will use to Spanish version of the SWLS (50).
Positive and negative affect. The Positive and Negative Affect Schedule ( PANAS) (51) presents 10 adjectives that reflect positive affect (e.g., interested) and 10 adjectives that represent negative affect (e.g., distressed). Positive and negative adjectives were mixed and presented in two columns, as shown by Watson et al. (51). Participants rated each adjective on a 5-point scale ranging from 1 (very slightly or not at all) to 5(extremely)..

Phase 4: PAP intervention
The intervention program will last 23 weeks, which were divided into three large blocks: Pre-evaluation. It will last a week. Throughout this phase, we will carry out an initial evaluation of the variables included in the PAP, to establish an initial starting point of the participants in the psychosocial, anthropometric and physiological variables.
Development of PAP sessions. This will last 21 weeks. Numerous cooperative, continuous activities will be carried out to develop the basic physical capacities: strength, endurance, speed and flexibility.
Post-evaluation. This will last 1 week. A final evaluation will be performed (same variables and instruments as in the initial evaluation) in order to compare them with the initial values and assess the effects produced by the PAP.
Retention measure. Transcription and analysis of the data. This will be performed 3 months after the PAP in order to know the effects produced over time. It will last for 3 weeks, during which the members of the EG and CG will be re-evaluated.

Justification of the PAP and dosis selection
With the ultimate goal of making the exercise program transferable to society, the basis and design of the PAP will comply with the recommendations proposed by the WHO [1].
Following the line of similar previous studies, the PAP will combine both aerobic and strength training. An important objective of the study is to assess adolescents' PA levels to determine whether they meet the values standardised by the WHO [1] and whether the PA levels of the EG outside the PAP increased compared to those of the CG, and to determine whether that behavior is maintained over time.
Trial duration will be five months, given the results of a RCT conducted previously with adolescents within the school environment. (29). Considering the increase in logistical and participation loads that could lead to poor adherence to PAP, as well as the cost of conducting a highly controlled study in a laboratory for a long time, the sessions of the intervention program will be given inside the gym of the corresponding school.

PAP volume
In order to make the results of the study easily transferable and understandable to the population in terms of time in minutes/week, intensity, and frequency, the recommendations of the PA level established by the WHO will be followed [1], so that three 60-minute sessions of mainly aerobic PA will be established.
It is estimated that 150 min/week of moderate intensity aerobic exercise (± 3-5.9 metabolic equivalents [MET, 1 MET = 3.5 ml O 2 /kg/min]) equals 1000 kcal/week, which is associated with lower rates of cardiovascular disease and premature mortality (52).
Therefore, the participants will establis this frequency and duration will accumulate the indicated of metabolic equivalents, obtaining such benefits for their health. An energy expenditure of 1000 kcal/week cal also be achieved with ± 75 min/week of vigorous intensity exericse (≥ 6 MET).

PAP frecuency
Studies on the frequency of exercise show small differences for 3 or more days a week, provided that the weekly dose of exercise is reached (52). Therefore, depending on the availability of the participants, a total of 3 weekly sessions will be established.
Participants will be advised to attend all PA sessions. The participants will be contacted when they miss a scheduled session to request them to perform an aerobic PA session, following the recommendations of the PAP researchers.

Type of exercise of the PAP
The activities of the aerobic exercise program will be developed by the PAP researchers.
In all the sessions, basic physical skills will be addressed: strength, endurance, speed and flexibility, as well as the motor capacities of coordination and balance. The dynamics of these sessions will be the establishment of "continuous activities carried out", with playful proposals, focused on the improvement of physical and psychosocial parameters.
The SDT postualates three basic psychological needs: competence (the desire to interact effectively with the environment), autonomy (the desire to choose freely and the feeling of being the initiator of one's actions) and relatedness (the desire to feel connected to respected by others). It also postulates that the satisfaction of these needs is essential for the development of self-determined motivation (53) and psychological well-being (9). The social environment plays an important role in the satisfaction or thwarting of these needs.
When authority figures support participants' autonomy, offering freedom and favoring participants' involvement in the decision-making process, then the basic psychological needs of autonomy, competence and relatedness are fulfilled. However, when these figures use a controlling style, acting coercively, exerting pressure, and behaving authoritatively, these needs are frustrated. Support of the basic psychological needs promotes more intrinsic and self-determined motives in task performance, increasing people's welfare (9). Taking this into account and to prevent dropout and need thwarting, and thus increase autonomy, competence and relatedness, the PAP will not be a closed program, but instead, participants' interests will be taken into account at all times, adapting the exercise and activities to participants' demands.

Variation of the PAP training load
We are aware that participants may not be immediately capable of physical exercise at the required dose of volume and intensity. Therefore, there will be a gradual progression to the training load. In addition, in view of the psychosocial benefits, the first sessions of the PAP will be used to encourage the participants' socialization.

Statistical analysis
The confidentiality of the data will be maintained at all times, since each student will be assigned a corresponding code, thus blinding the researcher who will process the database. The missing data, either due to dropout or non-compliance with the inclusion criteria established for the out-of-school PAP (attendance ≥ 80), will be treated using multiple methods of imputation, in accordance with the principle of Hollar et al. [54]. The normality of the variables will be verified and the results expressed as means, standard deviation, medians or different ranges. To evaluate possible predictors, multiple regression analysis will be performed on the independent variables of sedentary lifestyle, PA, anthropometric variables or health-related fitness and psychosocial variables. The comparisons between groups (EG vs. CG) of the continuous variables will be analyzed by means of analysis of variances or the nonparametric Kruskall-Wallis method, as well as Chi-squared tests, as appropriate. General linear models such as ANOVA, UNIANOVA, MANOVA, etc. will also be used to evaluate the effects of training among groups. Finally, mediation or moderation analyses will be conducted as appropriate, using the PROCESS macro for SPSS.

Potential impact of the multidisciplinary program for the promotion of PA and healthy habits in adolescents
This project contributes to one of the most important social challenges, taking into account the socio-economic impact that it will generate in Extremadura, as well as its potential to apply the results and transfer them to the productive sector. This project is of great interest to the scientific community as it will provide relevant information on IP issues, sedentary lifestyle, generation of healthy habits and physical exercise. PA seems to play a key role in the prevention and treatment of sedentary lifestyle and IP, and directly affects the prevention and treatment of overweight and obesity, as well as the improvement of body image, motivation toward PA, self-concept, satisfaction with life, etc., All this undoubtedly generates better performance in other aspects, such as school, future work or the acquisition of healthy habits, and has a high impact on the participants.
Related to the impact of the project, we propose to train teachers and monitors in appropriate motivational strategies to increase adherence to the practice of PA in society.
The increase of PA would lead to a decrease in public expenditure to alleviate the consequences caused by PI, as only one disease such as obesity, represents 7% of the expenditure of the Spanish National Health System, equal to 0.6% of Gross Domestic Product. In fact, in the "I Healthy Habits Day", held in Madrid in July, 2013, it was estimated that, for every euro that public administrations invest in the promotion and promotion of PA, a saving of 15 euros for health institutions is produced. That is, investment in the practice of PA not only benefits the population, but also leads to economic saving for the public institutions. Hence, the performance of PA by adolescents who were rather sedentary leads to a short-, medium-and long-term saving for the public administration.
This study integrates three different disciplines, the physiology of exercise, sports psychology and psychosocial consequences of sport in adolescents, to determine whether exercise can: (i) improve the levels of PA in adolescents through the design, development and evaluation of a multidisciplinary PA intervention program to promote healthier lifestyles; (ii) increase the levels of PA practice, and psychosocial and anthropometric variables among the EG adolescent participants, compared to the CG participants; and (iii) generate lasting healthy habits among the participants in the intervention program.
Exercise intervention can potentially translate into a moderate but "chronic" increase in total energy expenditure. Therefore, even if the PAP does not produce significant improvements in the psychosocial, anthropometric or physical variables, it could play a compensatory role of exercise and its protective effects against the development of overweight and obesity, as well as promote participants' social relationships.

Declarations
Ethics approval and consent to participate: Declaration of Helsinki, and its 2013 modification, and approved by the Human Research Ethics Committee of the University of Extremadura.

Consent for publication: no apply.
Availability of data and materials: no apply.
Competing interests: the authors declare that they have no competing interests develop. It will also be necessary to thank all the researchers involved, who will be responsible for exploiting the database generated from this project. The order of the authors of the publications derived from the project will vary depending on the degree of involvement of each researcher. In addition, by not using professional editors, the dedicated effort will be made during the preparation of each manuscript. Schedule of enrolment, interventions, and assessments.

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