Abstract: The heart rate (HR) response to specific physical exercise (ten squats at a maximum speed) in 122 boys and 128 girls who were 4–7 years of age and attended a kindergarten. All children were assigned to health groups 1 or 2. The heart rate was recorded at rest, during exercise, and in a recovery period (5 min) with Polar heart monitors. The intensity of HR debt accumulation (IHRDA) was calculated for each subject from the test results. There was no significant difference in physiological reactions between girls and boys. The exercise duration decreased with age, reflecting more intense test performance. IHRDA, which characterized the specific energy consumption, increased accordingly. A negative pulse phase was observed in some children during the recovery period. An analysis of individual pulse curves identified three variants of the HR response during exercise and the recovery period. The response type was not associated with sex, age, or anthropometric characteristics, but determined the final IHRDA value. Pairwise correlations were observed between anthropometric and functional parameters in the children 4 to 7 years of age. In general, the findings indicate that an individualized approach is important to use when planning physical activity and evaluating the efficiency of physical education in preschool children. © 2022, Pleiades Publishing, Inc.