Effects of frequency of static stretching on straight-leg raise in elementary school children

The aim of this study was to evaluate the efficacy of different frequencies of a stretching exercise program on lower extremity range of motion (ROM) in prepubertal schoolchildren.

A total of 62 children were divided into 3 groups (experimental groups: A, B; control group: C). Experimental group A performed hamstring stretches for 5 min during the Physical Education classes over a full school term (9 months), 2 sessions per week (31 weeks, 62 sessions of Physical Education). Experimental group B performed hamstring stretches for 5 min during the Physical Education classes and during a specific extracurricular physical activity, over a full school term (9 months), 4 sessions per week (31 weeks, 62 sessions of Physical Education and 62 sessions of after-school physical activities). Control group followed the standard class program of Physical Education classes. Hamstring flexibility was measured using the straight leg raise test before and after the program.

No significant differences were revealed in ROM before and after the Physical Education classes for the control group. However, significant improvements in ROM were shown in the two experimental groups (P<0.001). Four days per week produced a greater rate of gains in ROM (16.9 degrees) than 2 days per week (9.3 degrees). For all groups, the initial and the final ROM between the right and left sides were similar.

This study indicates that a full school term (9 months) incorporating static stretching as part of the Physical Education classes and the extracurricular physical activities significantly increases the ROM of the hamstrings in prepubertal schoolchildren. The study also suggests that the increase of the frequency of stretching is effective for increasing ROM.