LAUSR

ABSTRACT The World Health Organization recommends that children should engage in an average of 60 min of moderate-to-vigorous physical activity (MVPA) per day and should perform activities that strengthen muscle and bone at least 3 days a week. Public health professionals as well as pediatric researchers have identified schools as a strategic place to promote muscular strength development. Thus, the aim of this systematic review and meta-analysis was to investigate the efficacy of school-based exercise interventions for improving muscular fitness (MF) in children. Searches were conducted in three databases. Eligible criteria were randomized and non-randomized controlled trials evaluating the effects of school-based exercise interventions on MF (i.e. muscular strength, muscular power, and local muscular endurance) in children under 13 years of age. Risk of bias by the National Institutes of Health tool was appraised, and pooled effect sizes (Hedges’g) were calculated using random-effects inverse-variance analyses. Seventeen studies enrolling 1653 children (28% girls were analyzed). Exercise interventions, mostly combined interventions targeting selected domains of MF, were associated with significant moderate increases in local muscular endurance (g = 0.65 95% CI, 0.13 to 1.17, p = 0.020; I 2 = 85.0%) and muscular strength and muscular power (g = 0.33 95% CI, 0.16 to 0.51, p = 0.001; I 2 = 59.3%), with higher effects using interventions with ≥3 sessions per week. Our findings indicate that school-based exercise that includes strength building exercises may improve MF in children and, consequently, prepare modern day youth for the demands of exercise and sport activities. Highlights School-based muscle and bone strengthening exercises performed at least 3 days per week may serve to support the development of muscular fitness in girls and boys Integrative interventions that include a variety of strength and conditioning activities seem to be a promising strategy to promote muscular fitness in school environment Future research should standardize assessment methods for use with children in the school context and should include interventions with girls It is of interest to a growing number of health care providers, fitness professionals and physical education teachers to encourage participation in well-designed muscle and bone strengthening exercises.