[Changes in the succinate dehydrogenase activity in the muscle fibers of the m. quadriceps femoris of boys 7 to 17].

Different gradations of m. quadriceps femoris muscular fibres were revealed by means of histochemical method of succinate dehydrogenase activity determination in boys from 7 to 17-years old. Energetic profile of different types muscular fibres was shown to change unevenly in postnatal ontogenesis. Most muscular fibres tend to reduce oxidation activity by the age of 17. This proves the standing that muscular fibres are not stable structures and their energetic profile is dependent on the hormonal background of a growing organism.