Abstract
The article presents the theoretical aspects of physical work capacity and physical fitness of schoolchildren. These include: among the relationships, the greatest were noted between PWC170 and the values of the maximum work, as well as between running for 30 m and speed and strength endurance; with respect to physical conditions, boys had compliance with the required standards for resisting fatigue rather than strength; boys are more committed to strength work, and girls are more committed to flexibility. By means of correlation analysis, the features of the relationship between the values of physical work capacity and physical fitness of secondary school students are revealed. In girls of grades 5 and 9, a similar positive correlation was found between the power of the second load and cross-country skiing. According to the inverse relationship, such a trend was found between the PWC170 and the long jump from a place, running on skis. According to the inverse relationship, such a trend was found between the PWC170 and the long jump from a place, running on skis. In young men, a direct relationship was found between the power of the first load and pulling up on the crossbar, and no negative relationship was found. For teachers of physical education and secondary school students, instructions are offered for the further development of physical performance and physical fitness of students: exercises for improving the functions of the cardiovascular system. The results of the study can be applied in any country and in the implementation of the organization of the educational mechanism by physical education teachers to improve the physical performance of students and their physical self-improvement.