Effect Of School-based Physical Activity Programs On Hamstring Flexibility

Abstract

PURPOSE: Flexibility is an often neglected but very important physical fitness component that is gaining attention regarding its role in correct posture and the incidence of chronic injuries, especially among children and adolescents.The aim of the study was to examine the chronic effect of school-based physical activity (PA) programs on hamstring flexibility (HFlex) and to evaluate potential moderators of this effect using a meta-analytic approach. METHODS: A computerized literature search was conducted based on five databases: SPORTDiscus, Google Scholar, PubMed, Dialnet Plus, and MEDLINE. Studies needed to meet the following inclusion criteria to be included in the meta-analysis: 1) a randomized controlled trial design, 2) PA program took place in a school setting 3) published in English or Spanish, and 4) reported descriptive statistics that permitted effect size (ES) calculation. A random-effects model with a within-group design was used to calculate the ES. The moderator effects were analyzed either by one-way analysis of variance of independent groups or by Pearson product-moment correlation coefficients, depending on the variable considered. RESULTS: From 2006 articles, 13 studies representing 18 ES’s and totaling 792 participants (males and females, 10.3 ± 0.5 yo) were included in the analysis. The mean quality score for the studies was 3.4 ± 0.7 (on a scale from 1 to 5). A moderate overall ES of 0.38 (p ≤ 0.001; CI95% = 0.22 to 0.87; z=4.58; Q=13.38; I2=92.48%) was found suggesting a low-moderate effect of the school-based PA programs to enhance HFlex. Neither a) quality of the studies (r = -0.43, p = 0.87), b) number of intervention sessions (r = -0.16, p = 0.52), nor c) minutes per session (r = -0.03, p = 0.91) were significant moderators. Sex could not be included as a moderator because 78% of the studies did not report the effect on HFlex separately by sex. No bias was found according to Egger’s regression analysis (p=0.80). CONCLUSION: School-based PA programs have a significant positive overall effect on children and adolescents’ HFlex compared with their control peers. Reporting the effect differentiated by gender and including detailed group demographic data (i.e., experimental and control) is recommended for individual studies. KEYWORDS: hamstring flexibility, school-based physical activity