Physical activity and sport are associated with significant benefits when practiced regularly, starting at school age. In Colombia, physical education classes are not taught to children in primary school. The Institute for Sport and Recreation (Instituto de Deportes y Recreación, INDER) enables access to systematic sport practice, guided by a professional, for children of public schools in Medellin, Colombia. Purpose: To identify differences in anthropometric variables, concentration, motor skills, and cardiorespiratory capacity between school-aged children who participate in a sport program and those who do not participate. Methods: The research design is cross-sectional. 290 schoolchildren of both sexes were evaluated with the GRAMI-2 test to verify motor skills, the test of Toulouse-Piéron to verify their ability to concentrate, and the Course-Navette test to verify their cardiorespiratory capacity. There are 141 evaluated students who belong to the Inderescolares program (10.1 ± 1.9 years, mean ± SD) and 107 that do not belong to the program (9.5 ± 2.5 years, mean ± SD). With this sample, a statistical power of 79% is achieved, and inferences can be made with a confidence level of 95%. Results: The results indicate no differences in anthropometric variables between children who participate in the sport program and those not participating. There were significant differences in three tasks and proportional differences in all six tasks of the GRAMI-2 test in favor of those children who participated. Cardiorespiratory capacity is also better in children who participate in the program, INDER Medellin. This pattern of improved performance in the participating children occurs in both boys and girls. Socioeconomic status could affect the performance of some tests that require a greater expenditure of energy. Conclusion: Schoolchildren between eight and 11 years of age who are not taught physical education classes at school but participate in a sport program obtain better performance in the tests to assess motor skills, concentration, and cardiorespiratory capacity than those who are also not taught physical education classes at school nor participate in a sport program. Keywords: Physical Activity, Motor Skills, Concentration, Cardiorespiratory Capacity, Schoolchildren