Physical Activity and Fitness in Pediatric Inflammatory Bowel Disease

Pediatric inflammatory bowel disease (IBD), encompassing Crohn's disease and ulcerative colitis, is a chronic condition frequently diagnosed during childhood and adolescence. In addition to persistent intestinal inflammation, pediatric IBD is associated with reduced physical activity levels, impaired physical fitness, fatigue, musculoskeletal complaints, cognitive and psychosocial difficulties, and diminished health-related quality of life. Despite advances in pharmacological treatment, many children and adolescents continue to experience functional limitations that are not fully addressed by standard medical care.

Physical activity and physical fitness are modifiable lifestyle factors with well-established benefits in healthy pediatric populations, including anti-inflammatory effects, improved cardiorespiratory and muscular fitness, and better mental health and quality of life. However, in pediatric IBD, evidence remains limited, particularly from studies using objective measurements of physical activity and fitness, randomized controlled designs, and longitudinal follow-up in hospital-based settings. Furthermore, the relationships between physical activity, physical fitness, inflammation, clinical outcomes, and quality of life have not been comprehensively examined within a single integrated study framework.

This hospital-based study aims to evaluate the role of physical activity and physical fitness as modifiable factors influencing inflammation, clinical outcomes, and quality of life in children and adolescents with IBD. The study is conducted in three sequential phases: (1) an observational cross-sectional and longitudinal assessment, (2) a randomized controlled trial (RCT) of a structured physical activity intervention, and (3) a medium-term follow-up at 6 to 12 months.

In the observational phase, participants aged 8 to 17 years with a confirmed diagnosis of Crohn's disease or ulcerative colitis will undergo comprehensive baseline assessments. Physical activity will be measured objectively using accelerometry over seven consecutive days and supplemented by validated questionnaires. Physical fitness will be assessed using the ALPHA fitness battery adapted to the hospital environment, including cardiorespiratory fitness measured by the 20-meter shuttle run test, muscular strength, agility, and body composition. Clinical outcomes will include objective inflammatory markers (fecal calprotectin and C-reactive protein), disease activity indices (PCDAI or PUCAI), musculoskeletal health, fatigue, cognitive functioning, and health-related quality of life. Nutritional status and dietary quality will also be evaluated, and selected biological markers will be analyzed in a subsample.

In the interventional phase, eligible participants will be randomized to either a 12-week structured physical activity program or usual care. The intervention consists of supervised, age-appropriate exercise sessions combining aerobic and strength-based activities, tailored to participants' clinical status and functional capacity. The primary outcome of the RCT is the change in cardiorespiratory fitness, assessed by the number of laps completed in the 20-meter shuttle run test. Secondary outcomes include changes in inflammatory markers, disease activity indices, physical fitness components, fatigue, cognitive performance, nutritional status, and quality of life.

The follow-up phase will assess the sustainability of changes in physical activity, physical fitness, inflammation, and clinical outcomes at 6 to 12 months after baseline assessment or completion of the intervention. Longitudinal analyses will examine whether baseline and intervention-induced changes in physical activity and physical fitness predict medium-term clinical and patient-reported outcomes.

All questionnaires, cognitive assessments, and consent procedures will be administered electronically using secure institutional platforms. Data will be collected and stored in a pseudonymized manner in accordance with applicable data protection regulations.

This study is designed to provide high-quality, objective evidence on the clinical relevance of physical activity and physical fitness in pediatric IBD. By integrating functional, inflammatory, and patient-centered outcomes, the findings are expected to inform multidisciplinary care strategies and support the incorporation of structured physical activity into routine clinical management for children and adolescents with IBD.

• Speed and Agility (4 × 10 m Shuttle Run Test) [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Moderate-to-Vigorous Physical Activity (MVPA) [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Total Sedentary Time [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Lean Body Mass [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Body Fat Percentage [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Body Mass Index (BMI) z-Score [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Self-Reported Physical Activity (Physical Activity Questionnaire for Children PAQ-C) [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Self-Reported Physical Activity (Physical Activity Questionnaire for Adolescents PAQ-A) [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Fecal Calprotectin [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• C-Reactive Protein (CRP) [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Disease Activity (Pediatric Crohn's Disease Activity Index PCDAI) [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]
• Disease Activity (Pediatric Ulcerative Colitis Activity Index PUCAI) [Time frame: Baseline (Week 0), post-intervention (Week 12), and follow-up (6-12 months)]