20 younger pioneers (U-13) of the football club SN Maksimir from Zagreb was tested in the multistage 20 meter shuttle run test on the sound signal before and after the restriction of movement which was followed by the COVID-19 pandemic. They had an average value of 12.32 ± 0.56 years, body height 155.93 ± 6.13 cm, body weight 44.44 ± 6.47 kg, average years of training 5.41 ± 1.56 and the maximum oxygen uptake 41,66 ± 4,36 ml/kg/min. During quarantine, the number of independent weekly trainings they had was 1.68 ± 1.82. The aim of these analyzes was to determine that there is a statistically significant difference in the results of aerobic functional abilities before and after the COVID-19 pandemic. The average value of the multistage 20 meter shuttle run test on the sound signal before the COVID-19 pandemic was 8.65 ± 1.37 levels, which is 1371.00 ± 282.88 meters, and after the COVID-19 pandemic was 8.67 ± 1.41 levels, which is 1375.00 ± 302.75 meters which is 0,29% better than the first measurement. The average maximum speed Vmax (km/h) before the pandemic was 12,10 ± 0.70 km/h versus 12.13 ± 0.79 km/h after the COVID-19 pandemic. Subjective load sense (SOO) before COVID-19 was 15.1 ± 1.62 versus 14.45 ± 1.67 after the COVID-19 pandemic. The mean initial heart rate of the first measurement was 143.90 ± 18.88 beats / min versus 133.65 ± 16.32 beats / min after the COVID-19 pandemic. The mean maximum heart rate of the first measurement was 204.10 ± 12.69 beats / min versus 200.55 ± 11.28 beats / min after the COVID-19 pandemic. The results obtained showed that there was no statistically significant difference in aerobic performance scores before and after the COVID-19 pandemic. The break during the COVID-19 pandemic was not a limiting factor for young footballers who came after the break with approximately the same average level of training as before the COVID-19 pandemic, but on the other hand their further progress and development is delayed.