Effects of a stretching development and maintenance program on hamstring extensibility in schoolchildren: A cluster-randomized controlled trial

The main purpose of the present study was to examine the effects of a physical education-based stretching development and maintenance program on hamstring extensibility in schoolchildren. a sample of 150 schoolchildren aged 7-10 years old from a primary school participated in the present study (140 participants were finally included). the six classes balanced by grade were cluster randomly assigned to the experimental group 1 (n = 51),experimental group 2 (n = 51) or control group (n = 49) (i.e.,a cluster randomized controlled trial design was used). during the physical education classes,the students from the experimental groups 1 and 2 performed a four-minute stretching program twice a week for nine weeks (first semester). then,after a five-week period of detraining coinciding with the christmas holidays,the students from the experimental groups 1 and 2 completed another stretching program twice a week for eleven weeks (second semester). the students from the experimental group 1 continued performing the stretching program for four minutes while those from the experimental group 2 completed a flexibility maintenance program for only one minute. the results of the two-way analysis of variance showed that the physical education-based stretching development program significantly improved the students’ hamstring extensibility (p < 0.001),as well as that these gains obtained remained after the stretching maintenance program (p < 0.001). additionally,statistically significant differences between the two experimental groups were not found (p > 0.05). after a short-term stretching development program,a physical education-based stretching maintenance program of only one-minute sessions twice a week is effective in maintaining hamstring extensibility among schoolchildren. this knowledge could help and guide teachers to design programs that allow a feasible and effective development and maintenance of students’ flexibility in the physical education setting. © journal of sports science and medicine.