Inflammatory bowel diseases (IBDs), including Crohn's disease (CD), ulcerative colitis (UC) and IBD-unclassified (IBD-U), are characterised by chronic inflammation of the gastrointestinal tract. Over the past 50 years, the incidence of IBD has increased globally, with the highest increase in industrialised countries. During the last 25 years, the incidence of IBD has increased dramatically among teenagers in northern France, with an increase of 126% and 156% for CD and UC, respectively.

Physical fitness is a set of attributes related to a person's ability to perform physical activities that require aerobic capacity, endurance, strength or flexibility and is determined by a combination of regular physical activity and genetically inherited ability. Physical fitness, widely recognised as an important health determinant, plays an important role in growth and development. Due to the evidence-based importance of physical fitness for young people's health status, attention should be paid to the assessment of physical fitness at these ages and whatever the health status.

At this time, there is no study on the assessment of physical fitness in IBD pediatric patient.

Inclusion Criteria:

• For children with IBD:
• boy or girl aged 10 to 17 years old when signing the consent.
• obtain the consent of participation of the child and the signed inform consent of the two parents or a legal representative.
• Patient benefiting from health care- has IBD (Crohn's disease, ulcerative colitis and unclassified chronic colitis) for at least 6 months.
• Contactable by phone

For healthy controls:

• Patient without IBD
• Boy or girl aged 10 to 17 years old when signing the consent.
• obtain the consent of participation of the child and the signed inform consent of the two parents or a legal representative.
• Patient benefiting from health care

Exclusion Criteria:

• For children with IBD:
• Acute intercurrent events at the time of inclusion which may lead to a decrease in physical fitness and activity, according to the judgment of the investigator (fractures, recent arthritis, ano-perineal lesions, severe dermatological lesions).
• Patients with a disease a mild activity (PCDAI score > 30 for children with Crohn disease and PUCAI > 35 for children with ulcerative colitis.
• Chronic, acute or intermittent diseases (other than IBD) that may lead to a decrease in physical activity (Example: fracture, paralysis, blindness ...).
• Refusal of the child's participation in the protocol.
• Refusal of one of the child's parents to participate in the protocol.
• Participation in another interventional study.
• Pregnant or lactating women.
• Patient under protection of justice.

For healthy controls:

• Chronic, acute or intermittent diseases (other than IBD) that may lead to a decrease in physical fitness and activity (Example: fracture, paralysis, blindness ...).
• Refusal of the child's participation in the protocol.
• Refusal of one of the child's parents to participate in the protocol.
• Participation in another interventional study.
• Pregnant or lactating women.
• Patient under protection of justice.

Healthy children and adolescents with IBD (Crohn's disease, ulcerative colitis and chronic ulcerative colitis).

Data are available upon reasonable request. Data will be made available following the conclusion of the project's period of funding.