A Physical Education-based Stretching Program Performed Once a Week Also Improves Hamstring Extensibility in Schoolchildren: a Cluster-randomized Controlled Trial.

INTRODUCTION physical education teachers are required to carry out intervention programs for students to achieve health-enhancing flexibility levels. Unfortunately, to our knowledge, there are no studies examining the effect of a stretching program carried out only once a week on schoolchildren. OBJECTIVES the purpose of the present study was to compare the effects of a short-term stretching intervention program performed once and twice a week on hamstring extensibility among schoolchildren in the physical education setting. METHODS a sample of 180 high school students aged 12-14 years old was randomly assigned (by natural groups) to a control group, experimental group 1 and experimental group 2. During physical education classes, experimental group students performed a stretching program for eight weeks. The experimental group 1 and 2 performed the stretching program once and twice a week, respectively. RESULTS the analysis of variance results showed that the students of both experimental groups improved statistically significantly their hamstring extensibility when compared with the control group students (p < 0.01). Nevertheless, no statistically significant differences between the two experimental groups were found (p > 0.05). CONCLUSIONS a short-term stretching program performed only once a week improves hamstring extensibility in schoolchildren. When the stretching program is performed twice a week, the improvement in students'hamstring extensibility is not statistically higher.