According to the World Health Organization’s new recommendations on physical activity for children, regardless of living with disability or not, physical activity should be at least 60 minutes per day. Around the world, children are less and less physically active, leading to increased health risks. A healthy lifestyle, as being physically active, is normally set during childhood and adolescence, making children an important group to study and target. This Research Topic will address physiological health effects related to physical activity and exercise among children, regardless of living with disability or not, and how to assess these effects in a valid and reliable way. Children do not respond to physical activity and exercise in the same way as adults do due to unmatured physiology. Living with a disability may also affect the child’s response to physical activity and exercise. In order to be able to follow and prescribe physical activity and exercise to children, rigorous knowledge is needed on how children respond to different physical activity and exercise regimes. Additionally, to be able to follow and prescribe physical activity and exercise to children, valid and reliable assessment methods are needed. Not only do the tests need to be valid and reliable, but also common standards on how to interpret them are required. This Frontiers Research Topic seeks a broad range of original research articles, systematic review articles and meta-analyses in the area of “physical activity and exercise among children” including: -Physical activity assessments which are age- and ability-adjusted, -Fitness assessments which are age- and ability-adjusted, -Effects on health-related outcomes in relation to different physical activity interventions which are age- and ability-adapted, -Effects on health-related outcomes in relation to different exercise interventions which are age- and ability-adapted.