The primary objective of this research is to gain novel insights into the potential of physical activity in reducing fatigue, improving QoL and GI manifestations in children with IBD. The study design will be composed of two parallel groups to investigate the role of physical activity: on the one hand patients with higher exercise habits, on the other hand children with lower exercise habits. To this end, the two groups of pediatric IBD patients will undergo a 24 weeks exercise programme, adjunctive to their current treatment, quantified by a Health Smartwatch (Garmin Inc.). The primary outcomes will then be characterized by the PedsQoL-MFS, IMPACT-III, PCDAI and PUCAI questionnaires, as well as VO2-max quantification. The proposed research will confirm or refute current hypotheses about physical training suggesting an improvement in quality of life (QoL), fatigue and bowel symptoms in children with IBD. Furthermore, investigating the effectiveness on secondary outcomes including muscle strength and aerobic capacity will be a new contribution to current knowledge.