The main aim is to present the sports game Brenbal as an attractive game suitable for the development of aerobic fitness for children of school age within outdoor activities (PE, courses, residential outdoor schools, etc.). The research part of the project is dealing with the intensity of motion load using the Brenbal game. 76 probands 12-13 years of age have participated in measuring research realised at two elementary schools in Liberec. To implement the project monitors of the heart rate, Polar 800CX were used allowing individual setting up the zones of intensity. Zones 2-4 (60-89% HR max) were tracked dominantly and the number of minutes spent in them. The measured section was a 45-minute teaching unit. During the implementation of the Brenbal game, the file of girls and boys achieved 25 min 36 sec (56% of the time) of 45 min in zones 2-4. During intersexual distribution, the boys file was more active with the time of 25 min 51 s (57.47% of the time) in zones 2-4. The girls file achieved time of 25 min 18 s (56.23% of the time) in zones 2-4. Based on the research, the attractive Brenbal game can be recommended ideally suited for the development of children's aerobic fitness.