The goal of this clinical study is to learn whether a psychologist- or psychotherapist-guided physical activity program can be delivered and used as part of regular care for adults experiencing stress-related exhaustion. The program is designed to be integrated into regular psychological treatment as usual and supports participants in developing physical activity habits in a gradual, individualized, and sustainable way.

The main questions this study aims to answer are:

• Can participants complete the program and attend the planned sessions?
• Do participants and clinicians find the program acceptable, relevant, and useful?
• Is the program safe, and do any negative experiences occur during the program?
• What practical barriers and facilitators affect participation and delivery in routine care?
• What descriptive patterns of change are seen in physical activity, symptoms, and everyday functioning from before to after the program?

The program is based on cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT). It includes strategies to help participants set meaningful goals, take step-by-step actions toward those goals, and respond more flexibly to uncomfortable thoughts, emotions, and body sensations that may arise in relation to physical activity.

About 12 to 20 participants will take part. The program is designed to be integrated into about 5 to 6 individual sessions delivered over a flexible time period, depending on each participant's pace and circumstances.

Participants will:

• Take part in the physical activity program as part of their regular psychological treatment
• Complete online questionnaires before and after the program
• Log their physical activity during the program
• Provide feedback after the program (and some participants will also take part in an interview)

The results will be used to assess whether the program is feasible and acceptable for participants and clinicians and to inform further refinement and future evaluation.

Background and rationale Prolonged psychosocial stress can lead to substantial exhaustion, often accompanied by impaired cognitive function, sleep disturbance, and reduced everyday functioning. In Sweden, these difficulties have often been described within the diagnosis exhaustion disorder (ED), introduced in 2003 (International Classification of Diseases, 10th Revision, Swedish adaptation; ICD-10-SE F43.8A). ED is associated with high rates of sick leave and substantial societal costs. With the transition to the World Health Organization (WHO) International Classification of Diseases, 11th Revision (ICD-11), this national diagnosis will be phased out in 2028; however, the clinical problems it captures are expected to remain prevalent. There is therefore a need to continue developing and evaluating feasible and scalable rehabilitation approaches for individuals experiencing stress-related exhaustion.

Physical activity has well-documented preventive and rehabilitative effects on mental health problems such as depression, anxiety, and stress, but its role in rehabilitation for stress-related exhaustion has been less studied. In clinical practice, physical activity may be approached with caution in this group, and treatment recommendations have often emphasized rest and low-intensity activity. Many individuals struggle to reintroduce activity in a sustainable way: some avoid activity due to fear of symptom worsening, while others push themselves too hard. Over time, both patterns may contribute to persistent fatigue and reduced functioning.

A psychologically informed and individually tailored approach to graded physical activity may help participants develop a more sustainable activity pattern by supporting pacing and gradual progression, addressing avoidance and overexertion patterns, and strengthening engagement in meaningful life domains.

Intervention framework and development The intervention was developed within a broader research program on physical activity in stress-related exhaustion, including an experimental study on responses to acute exercise and a qualitative interview study on experiences and perceptions of physical activity during rehabilitation. Findings from these studies informed the content and delivery procedures of the present intervention.

The intervention is grounded in cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT) principles and draws on established behavior change theories, including Social Cognitive Theory and dual-process models. Key processes targeted include self-efficacy, behavioral activation, and psychological flexibility. The intervention aims to support sustainable behavior change through values clarification, behavioral strategies, and gradual exposure to activity-related discomfort.

In line with guidance from the United Kingdom Medical Research Council (MRC) framework for developing and evaluating complex interventions, the present study is an early-stage evaluation focused on feasibility and acceptability. Findings will inform intervention refinement and planning of future evaluation.

Study design and setting This is a single-arm interventional feasibility study conducted in routine clinical care. All participants receive the intervention; there is no control or comparator arm. The program is delivered by licensed psychologists and psychotherapists and is designed to be integrated into regular psychological treatment as usual in clinical settings where stress-related exhaustion is commonly treated, including occupational health care and primary care. No masking is applied (open label), and allocation is not applicable.

A mixed-methods design is used to evaluate feasibility and explore participant and clinician experiences. Quantitative and qualitative data are collected in parallel and integrated during interpretation.

Participants and recruitment Adults meeting the protocol inclusion and exclusion criteria will be recruited consecutively via collaborating clinicians. The target sample size is approximately 12-20 participants, consistent with feasibility study guidance aimed at assessing acceptability, practicality, and safety and informing refinement of the intervention and study procedures.

Intervention description The intervention is a manualized CBT-based physical activity program integrated into psychological treatment as usual. It is individually tailored and structured to support participants in building sustainable physical activity habits through values-based work, behavioral strategies, and gradual progression.

The program acknowledges that individuals experiencing stress-related exhaustion may differ in functional profile and activity patterns. Some may avoid activity due to fear of symptom worsening or relapse, while others may struggle with overexertion. The intervention therefore emphasizes individualized pacing and progression and supports participants in responding flexibly to internal experiences such as fatigue-related sensations, thoughts, and emotions that may arise before, during, or after physical activity.

Key components include:

• Psychoeducation about fatigue and recovery processes and the role of physical activity from behavioral and learning-based perspectives
• Values clarification to support engagement in personally meaningful life domains
• Goal setting and action planning using graded task assignment and stepwise progression
• Graded exposure to physical activity, adapted to individual capacity and functional status
• Skills for responding flexibly to unhelpful thoughts and emotions related to physical activity, fatigue, performance, and relapse concerns
• Reflection on activity experiences, including affective responses, to support learning and motivation

The program is designed to be integrated into approximately 5-6 individual sessions delivered over a flexible time period depending on the participant's pace and circumstances. Brief home tasks are included between sessions.

Data collection procedures Quantitative and qualitative data are collected to evaluate feasibility and acceptability and to inform refinement of the intervention and study procedures.

Participants complete digital self-report questionnaires at baseline (approximately 1 week before program start) and post-intervention (approximately 1 week after program completion). During the intervention period, participants provide brief monitoring data related to physical activity engagement (date, duration, type of activity, rating of perceived exertion [RPE]) .

After completing the intervention, participants provide structured feedback about their experiences, and a subset participate in semi-structured interviews to explore perceived helpful and hindering aspects, barriers and facilitators, and suggestions for improvement. Psychologists and psychotherapists delivering the program also complete structured feasibility-related documentation to support evaluation of delivery and implementation in routine care.

To capture other potentially relevant care received during the intervention period, participants complete a brief post-intervention questionnaire on health care utilization adapted from the Trimbos and iMTA questionnaire on Costs associated with Psychiatric illness (TIC-P). These data are collected to contextualize feasibility findings and descriptive outcome patterns rather than as a treatment outcome.

Feasibility focus and outcomes reporting The primary purpose of the study is to evaluate whether the intervention and study procedures are feasible and acceptable in primarily by adults with stress-related exhaustion, and also by clinicians in routine clinical settings. Feasibility is assessed using multiple pre-specified indicators, including intervention completion, attendance, adherence to intervention activities, fidelity of delivery, acceptability, and safety. These indicators are specified as separate outcome measures in the ClinicalTrials.gov record. Overall conclusions regarding feasibility will be based on combined interpretation of quantitative indicators and qualitative feedback.

In addition, descriptive pre-post patterns in participant-reported outcomes will be examined to support intervention refinement and planning of future evaluation (specified as separate outcome measures in the ClinicalTrials.gov record). The study is not designed or powered to provide confirmatory evidence of effectiveness.

Safety monitoring Safety is monitored throughout the intervention period. Any reported or observed adverse experiences (physical or psychological) are documented by the treating psychologist or psychotherapist. Participant feedback collected post-intervention is used to supplement safety documentation and capture experiences that may not have been reported during sessions.

Data analysis and mixed methods integration Quantitative data will be summarized using descriptive statistics. Exploratory analyses may be conducted to describe patterns of change and potential covariates using repeated-measures approaches, recognizing that the sample size is limited and that analyses are not confirmatory.

Qualitative interview data will be analyzed using thematic analysis, with inductive coding and theme development to capture participant experiences, perceived helpful and hindering aspects, and suggestions for refinement.

Quantitative and qualitative data will be analyzed separately and integrated at interpretation using joint displays and triangulation. Integration will be used to identify convergence, complementarity, and discrepancies across data sources to inform refinement of the intervention and support planning of future evaluation.

Progression considerations Decisions about further evaluation will primarily be informed by feasibility indicators and qualitative feedback on burden, fit, and perceived usefulness of the intervention. Findings will be used to refine the intervention and inform the design of a future larger-scale study.

Inclusion Criteria

• Adult aged 20 to 64 years.
• Experiencing stress-related exhaustion, assessed in regular clinical care (for example, symptoms consistent with exhaustion disorder or a closely related stress-related condition).
• Symptoms are not in the acute phase (participant is able to engage in outpatient psychological treatment and gradual physical activity).
• Elevated fatigue/exhaustion at screening, indicated by scores on screening questionnaires (Karolinska Exhaustion Disorder Scale and Multidimensional Fatigue Inventory).
• Able to understand spoken and written Swedish.
• Has access to a smartphone, tablet, or computer with an internet connection to complete study questionnaires and activity logging.
• No medical condition that makes physical activity unsafe, based on clinical screening and participant self-report.

Exclusion Criteria

• Currently receiving psychological treatment outside the recruiting clinic that is expected to interfere with participation in the program or study assessments.
• Current or past diagnosis of a psychotic disorder.
• Current or past diagnosis of bipolar disorder.
• Severe mental health condition requiring another primary treatment approach at this time (for example, severe major depressive disorder, post-traumatic stress disorder, or an eating disorder).
• Ongoing substance use disorder.
• Medical condition or acute illness that makes physical activity inappropriate at this time (for example, recent blood clot, severe infection, or other serious condition).
• Severe musculoskeletal condition that substantially limits ability to perform physical activity.
• Started antidepressant medication within the past 4 weeks.

Additional notes (not eligibility criteria):

Participants may use psychotropic medication (for example, antidepressants, sleep medication, or anxiety medication) if the medication regimen is stable. Participants will be asked to report any medication changes during the study period. Mild to moderate comorbid anxiety or depression is allowed if stress-related exhaustion is the primary clinical problem.

The data analyzed or produced in this study will not be openly accessible due to Swedish legislation (the Swedish Ethical Review Act: 2003:460) but the authors can provide access upon reasonable request. For such inquiries, please contact Victoria Blom, victoria.blom@gih.se.