Improving hamstring flexibility through physical education based interventions : a systematic review and meta-analysis

Flexibility is recognized as a strong marker of physical health in children. Scientific research has indicated that there is a worldwide decline in children's physical fitness, including a reduction in flexibility levels. It has been suggested that a lack of flexibility in youth may be responsible for several health complications, including back pain, injury risk, and posture problems. Physical education (PE) classes are part of the school curriculum, which are an ideal setting to improve children physical fitness levels. The purpose of this systematic review and meta-analysis was to investigate whether incorporating a stretching component during regular PE classes can improve flexibility in school children. Three electronic databases were searched systematically until June 2019 for studies analysing the effects of interventions performed during PE classes aimed to improve the flexibility levels of school children (6-18 years). The critical appraisal was carried using PEDro and MINORS scales and a meta-analysis was performed. Seventeen studies of moderate-to-high methodological quality were included in the review and 14 in the meta-analysis, pooling 874 participants. The interventions showed significant improvements in the flexibility of the children, although the relative influence of genre could not be further analysed, due to the fact that insufficient data was reported. The meta-analysis for the hamstring flexibility resulted in a significant moderate effect. Flexibility levels can be improved through the incorporation of stretching interventions during PE classes, since flexibility is a key health-related physical fitness componentFurther research is needed on the effects of such interventions on trunk and upper body flexibility. © 2022 Authors. All rights reserved