Zoran Mijić
Elementary school "Stojan Novaković", Šabac.

indent Abstract
The aim of the research was to determine an optimum track length for cross competition of the senior pupils of both genders of school age. The research of longitudinal character was carried out in one half-term with 560 pupils of the elementary schools "Stojan Novakovic" from Sabac. The sample included 4 sub samples (V-VIII class both genders). The model of pedagogic experiment was applied with parallel groups, experimental and control. The first group consisted of pupils of control group (each class separately) who worked according to the existing curriculum for elementary schools that included preparation for cross competitions. The second group consisted of pupils of experimental group who used experimental program of preparation for cross competition. The results of the research showed that experimental program was more efficient. The optimum track lengths were determined for cross competitions of senior schoolchildren: schoolchildren V class - 900/1.300 м; VI – 900/1.500 м; VII – 1.000/1.600 м; VIII – 1.100/1.800 м.