Comparison between warm-up and cool-down stretchingprograms on hamstring extensibility gains in primaryschoolchildren

The purpose of this study was to compare the effects of a physical education-based stretching programperformed during warm-up and cool-down periods on hamstring extensibility in schoolchildren aged 9-10 years. A sample of 73 schoolchildren, 36 boys and 37 girls, aged 9-10 years old from three classeswere clustered randomly assigned to a no-training group (n = 24), warm-up group (n = 25), or cool-down group (n = 24). During physical education classes, the students of the warm-up and cool-downgroups performed a four-minute stretching program twice a week for ten weeks during the warm-up andthe cool-down periods, respectively. Hamstring extensibility was estimated by the classic sit-and-reachtest at the beginning and at the end of the stretching intervention program. The results of the ANOVAshowed that both the warm-up and cool-down students had statistically significant higher values on thehamstring extensibility than the no-training students (p < 0.05). The warm-up and cool-down groupsdid not show statistically significant differences. Nevertheless, the cool-down students obtained aslightly higher magnitude effect when compared with the warm-up group (g = 0.67 and g = 0.56,respectively). In addition to the slight higher improvement during the cool-down, due to the negativeeffect of static stretching on performance as previously found in the literature, it seems that physicaleducation teachers should improve students ́ flexibility during the cool-down period of the sessions.