SDT-Based Intervention for Exercise Motivation in Female Students (No acronym use)

Study Protocol for a Randomized Controlled Trial of a Self-determination Theory-Based Psychoeducational Intervention to Enhance Autonomous Motivation for Exercise in Female University Students

Physical inactivity, maladaptive exercise motives, and body image concerns are highly prevalent among young adult women and are associated with reduced psychological well-being and increased risk for disordered eating. This study protocol describes a randomized controlled trial designed to evaluate a multi-component psychoeducational intervention integrating Self-Determination Theory principles with functionality-oriented body image strategies to enhance autonomous motivation for exercise and promote psychological well-being among female university students. Female Health Sciences students aged 18-25 will be randomly allocated (1:1) to an experimental or control group following baseline assessment, and outcomes will be evaluated at baseline, post-intervention, and six-week follow-up. The six-session face-to-face intervention incorporates autonomy-supportive communication, competence-building activities, meaningful rationales, choice provision, and supportive relational climates, combined with functionality-based body image content. The primary outcome is autonomous motivation for exercise (BREQ-3; Relative Autonomy Index), and secondary outcomes include basic psychological need satisfaction and frustration, physical activity levels, positive body image, and eating disorder risk. Linear mixed-effects models will be used under an intention-to-treat approach, and mediation analyses will test whether changes in psychological need satisfaction underlie improvements in motivational quality. The intervention is expected to promote healthier motivational regulation, increase physical activity engagement, strengthen positive body image, and reduce maladaptive exercise drivers. Findings aim to inform scalable, theory-driven preventive strategies for improving health and well-being among young women in university settings.

Study Overview

• Status: Not yet recruiting
• Conditions: Physical Activity; Body Image
• Intervention / Treatment: Behavioral: Experimental group will receive a face-to-face psychoeducational program grounded in Self-Determination Theory. Control group will no receive any psychoeducational program

• Study Type: Interventional
• Enrollment (Estimated): 194
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Patricia Ruiz-Bravo, PA and Sport Sciences; Phone Number: 1939 +34917091400; Email: p.ruiz.prof@ufv.es

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Female sex
• Age between 18 and 25 years
• Enrolled in Health Sciences programs (Physical Activity and Sport Sciences, Physiotherapy, Human Nutrition and Dietetics, Nursing) at Universidad Francisco de Vitoria
• Provision of written informed consent

Exclusion Criteria:

• Current or previous diagnosis of an eating disorder
• Failure to complete baseline or post-intervention questionnaires
• Identification of an eating disorder after enrollment, which triggers referral according to the well-being protocol

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intervention Group; Participants in the intervention group will attend a six-session psychoeducational program, delivered weekly in small groups.	Behavioral: Experimental group will receive a face-to-face psychoeducational program grounded in Self-Determination Theory. Control group will no receive any psychoeducational program; Participants in the experimental group will receive a face-to-face psychoeducational program grounded in Self-Determination Theory. The intervention consists of six 60-minute weekly group workshops (up to 15 participants per group). Sessions include autonomy-supportive communication, competence-building activities, functionality-oriented body image content, experiential tasks, and guided reflection. Facilitators are trained professionals in exercise science and psychonutrition who follow a standardized session guide. Intervention fidelity is monitored using session checklists. Workshop content progresses through: Awareness of motivational quality Personal values and self-endorsed goals Competence and flexible planning Functionality-oriented body appreciation Social support and supportive relational climate Maintenance of behavior change and coping with setbacks
No Intervention: Control Group; Participants assigned to the control group will remain on the wait-list during the intervention and follow-up periods and will not receive any specific intervention.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
RAI continuous score	Measured using the Behavioral Regulation in Exercise Questionnaire-3 (BREQ-3). The Relative Autonomy Index (RAI) was calculated by weighting the six regulation subscales (Amotivation -3, External -2, Introjected -1, Identified +1, Integrated +2, Intrinsic +3) and summing the weighted mean scores. Higher (positive) scores indicate more autonomous forms of motivation, whereas lower (negative) scores reflect more controlled forms of regulation. Because the RAI is computed from mean subscale scores, its theoretical limits depend on the 0-4 response scale and the weighting structure; for typical BREQ-3 scoring, values fall approximately between -12 and +12.	Assessed at three time points: baseline (Day 0), immediately after the 6-week intervention (post-intervention), and at 6-week follow-up.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Autonomy, competence, relatedness (satisfaction subscales)	Measured using the Basic Psychological Need Satisfaction and Frustration Scale (BPNSFS). This instrument assesses both satisfaction and frustration of the three basic psychological needs, autonomy, competence, and relatedness, within the framework of Self-Determination Theory. Items are rated on a 5-point Likert scale ranging from 1 (not at all true) to 5 (completely true). Subscale scores were computed as the mean of the corresponding items, resulting in scores ranging from 1 to 5 for each dimension. Higher scores on the satisfaction subscales indicate greater need satisfaction, whereas higher scores on the frustration subscales reflect greater need frustration. The scale demonstrates a six-factor structure, comprising autonomy, competence, and relatedness satisfaction and frustration dimensions.	Assessed at three time points: baseline (Day 0), immediately after the 6-week intervention (post-intervention), and at 6-week follow-up.
Weekly MET-minutes	Physical activity was assessed using the International Physical Activity Questionnaire-Short Form (IPAQ-SF). This instrument evaluates the frequency (days per week) and duration (minutes per day) of walking, moderate-intensity, and vigorous-intensity physical activity performed during the previous 7 days. Total physical activity was expressed in metabolic equivalent minutes per week (MET-min/week), following the official IPAQ scoring protocol. MET-min/week values were obtained by multiplying the assigned MET coefficient of each activity category by the corresponding minutes and days: walking (3.3 METs), moderate-intensity activity (4.0 METs), and vigorous-intensity activity (8.0 METs), and summing the results across all categories. Total scores range from 0 MET-min/week to theoretically unbounded values, depending on the volume of physical activity accumulated. Higher scores indicate higher levels of physical activity.	Assessed at three time points: baseline (Day 0), immediately after the 6-week intervention (post-intervention), and at 6-week follow-up.
BAS-2 total score	Body appreciation was assessed using the Body Appreciation Scale-2 (BAS-2), a 10-item measure of positive body image. Items are rated on a 5-point Likert scale ranging from 1 (never) to 5 (always). Scores were computed as the mean of all items, resulting in a total score ranging from 1 to 5. Higher scores indicate greater body appreciation, reflecting acceptance, respect, and positive attitudes toward one's body. The BAS-2 has demonstrated strong psychometric properties and a robust unidimensional factor structure across different populations.	Assessed at three time points: baseline (Day 0), immediately after the 6-week intervention (post-intervention), and at 6-week follow-up.
EAT-26 total score	Disordered eating attitudes were assessed using the Eating Attitudes Test-26 (EAT-26). The instrument consists of 26 items assessing symptoms and concerns characteristic of eating disorders. Items are scored on a 6-point Likert scale, which is recoded into a 4-point scale ranging from 0 to 3 (Always = 3, Usually = 2, Often = 1, and Sometimes/Rarely/Never = 0), following standard scoring procedures. Total scores are obtained by summing all items, resulting in a range from 0 to 78. Higher scores indicate greater eating-related concerns and a higher risk of disordered eating. A total score of 20 or higher is commonly used as a screening cut-off indicating elevated risk and the potential need for further clinical evaluation.	Assessed at three time points: baseline (Day 0), immediately after the 6-week intervention (post-intervention), and at 6-week follow-up.

Collaborators and Investigators

• Sponsor: Universidad Francisco de Vitoria

Study record dates

Study Major Dates

• Study Start (Estimated): October 1, 2026
• Primary Completion (Estimated): February 20, 2027
• Study Completion (Estimated): April 30, 2027

Study Registration Dates

• First Submitted: March 23, 2026
• First Submitted That Met QC Criteria: March 27, 2026
• First Posted (Actual): April 1, 2026

Study Record Updates

• Last Update Posted (Actual): April 1, 2026
• Last Update Submitted That Met QC Criteria: March 27, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: SDT theory; Gender gap; ED risk
• Additional Relevant MeSH Terms: Behavior; Motor Activity
• Other Study ID Numbers: UFV2026-22

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: The treatment of personal data will strictly comply with Regulation (EU) 2016/679 (General Data Protection Regulation, GDPR), ensuring the reconciliation of the right to data protection with the freedom of scientific research.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No