Sensitive periods of flexibility development at school age

The objective is to identify sensitive periods for the accentuated development of flexibility of schoolchildren. Methods: the scientific research was conducted on the basis of 60 schools in the city of Kirov, in Russia from September 14, 2022 to May 22, 2023. The pedagogical experiment involved 1,217 children (579 boys and 638 girls) from grades 1 to 11 of secondary school number 60 Kirov, Russia. Each lesson in the discipline "Physical education" lasted 40 minutes and took place 3 times a week. All students were engaged in the usual physical education program at school. All students took the tests at the beginning and at the end of the school year. The level of flexibility development was determined by the test "Leaning forward from a standing position on a gymnastic bench." Excel was used to process the results of the study, the Biostatistics-2022 program determined the reliability of the results of the T-Student study. Results: After the end of the study, the average indicators in each age group increased during the academic year. In the indicators of boys from the beginning to the end of the study, there was a significant and significant increase in flexibility indicators in the second grade (+15%), in the third grade (+17%) and in the fourth grade (+15%). In girls, a significant increase in the value is noted in the third grade (+16%), fifth grade (+14%) and sixth grade (+15%). In other age periods, there is not a significant increase in flexibility indicators (p>0.05). Conclusion: As a result of this large-scale study, it can be argued that the targeted development of flexibility should be in boys aged 8 to 11 years, and in girls aged 9-10 years, 11-12 years and 12-13 years. El objetivo es identificar períodos sensibles para el desarrollo acentuado de la flexibilidad de los escolares. Métodos: la investigación científica se llevó a cabo sobre la base de 60 escuelas en la ciudad de Kirov, en Rusia, del 14 de septiembre de 2022 al 22 de mayo de 2023. El experimento pedagógico involucró a 1.217 niños (579 niños y 638 niñas) de los grados 1 a 11 de la escuela secundaria número 60 Kirov, Rusia. Cada lección de la disciplina "Educación física" duró 40 minutos y se llevó a cabo 3 veces por semana. Todos los estudiantes participaron en el programa habitual de educación física en la escuela. Todos los estudiantes tomaron las pruebas al principio y al final del año escolar. El nivel de desarrollo de la flexibilidad se determinó mediante la prueba "Inclinarse h