This study is an observational study. The purpose of this study is to assess the relationship between bone health and daily physical activity in children and adolescents with inflammatory bowel disease (IBD). Reduced bone mineral density is a common complication in pediatric IBD. Physical activity is an important determinant of health throughout the whole lifespan. Engaging in regular moderate-to-vigorous physical activity has important health benefits. Based on available evidence, the investigators hypothesize that daily moderate-to-vigorous physical activity could improve bone health (ie bone mineral density) in children and adolescents with IBD.