Body Mass Index and Sedentary Behaviour Affect Hamstring Extensibility in Primary Education Students.

Enhancing and maintaining physical condition is an essential element of physical education for primary school children. In this respect, flexibility is of crucial importance in physical performance and coordination. One of the areas addressed in physical education is that of increasing hamstring flexibility, which is diminished by physical inactivity and inversely associated with the body mass index. The objective of this study is to explore the interplay between hamstring extensibility, physical inactivity and overweight in primary school students. Accordingly, a cross-sectional descriptive study was carried out of 265 students, applying sit and reach (SR) and deep trunk flexion (DTF) tests and analysing responses made to the IPAQ questionnaire. Among the results found for the study sample, the average flexor capacity recorded was -0.26 ± 6.33 among the boys and 5.52 ± 6.46 among the girls. The highest values in the girls were achieved at 9-10 years of age (6.69 ± 8.19) and in the boys at 6-7 years of age (2.72 ± 5.99). The lowest values for the girls (3.30 ± 5.19) were recorded in those aged 8-9 years and for the boys (3.13 ± 5.60) at the same age. These study results suggest there is a relationship between a sedentary lifestyle, a high BMI and sub-optimum flexibility. The children identified as physically active obtained higher average results in both the SR and the DTF tests.