The aim of the research was to contribute to better understanding of the correlation between postural disorders and muscle power in primary school children. The sample of respondents consisted of 1,120 children, aged 7 to 12 years (549 boys and 571 girls) from the territory of the municipality of Knjaževac. In the assessment of the spinal column status, the device "Spinal Mouse" (Switzerland) was used, while in the analysis of the status of the feet, the podoscope "Pedic" (Hungary) was used. A handheld dynamometer "Lafayette" (USA) and tensiometric force platform "Vernier Force Plate" (USA) were used in the analysis of muscle power. Spinal column and feet status were measured in the static condition, with children being in the upright standing position. Muscle power status was measured in both static (a clinician was applying muscle force to the dominant upper extremity of a child trying to overcome or "break" the child's muscle resistance) and dynamic conditions (Counter Movement Jump). Descriptive statistics and correlation analysis were used in data processing by the means of the SPSS software version 24. Results revealed poor postural and muscle power status, and correlations suggesting to possible kinetic chain reaction causing the disruption of the normal postural status in primary school children. Determined postural disorders are characterized by the early functional stage that can be reduced by appropriate corrective exercise programme application and augmented level of proper physical activity. Those programmes and activities are being guided and implemented by physicians and PE teachers in the municipality of Knjaževac.

Vertical jump is one of the most common ways to evaluate the explosive power of lower extremities in athletes. For the development of explosive power, plyometric exercises are mostly used as a form of training. Participants were handball players (N=13), volleyball players (N=13) and basketball players (N=13) from city of Nis. They all competed in the highest state competition. After analyze all data conclusions are that the mechanical characteristics estimated by the accelerometer are statistically not significantly different in the examined athletes' groups except in the jump height and the kinematic characteristics of the vertical jump obtained by the video analysis statistically do not differ significantly, except in the variations of the angular velocity in the hip joint in the ankle.