Secondary-School-Based Interventions to Improve Muscular Strength in Adolescents: A Systematic Review

Physical education is considered an ideal environment for improving physical fitness and muscle strength through exercise and training. This systematic review aimed to analyze studies where an intervention was implemented in Secondary School Physical Education classes to improve muscle strength. The literature search was carried out in the SPORTDiscus, PubMed, Web of Science and ScienceDirect databases. We selected randomized and nonrandomized interventions conducted in Physical Education with adolescents aged 13–18 years, where muscle strength was evaluated, comparing a control group with one or more experimental groups. From the identified works after applying the levels of screening and eligibility, eight articles were chosen for the final analysis. Data collection and risk of bias assessment were performed independently by a single reviewer. The interventions of the included studies employed varied training loads, materials, and exercises. Significant improvements were achieved in all interventions for different strength measurement tests such as the Countermovement Jump (CMJ), Standing Long Jump (SLJ) and Squat Jump (SJ) tests, medicine ball throwing test, maximum isometric strength, manual dynamometry, push-up and curl-up tests, and maximum repetition tests. Strength training can be applied safely and effectively in Secondary Education. However, methodological differences in interventions have been identified; therefore, further research is needed.