Edpuzzle-based strength training in after-school settings: a randomized controlled trial

Abstract

The school Physical Education subject has a limited class time, which is insufficient to achieve the physical activity recommendations, making complementary extracurricular interventions necessary. This study analyzed the effects of a strength-endurance training program, promoted through the Physical Education (PE) class, on anthropometric and physical fitness of adolescents; the differences based on sex; and their opinions on satisfaction, usefulness, and reasons for dropping out of the program according to sex. A randomized controlled trial was conducted with 107 adolescents randomly assigned by class cluster to an experimental (EG: n=52) or control (CG: n=55) groups. For 12 weeks, the EG was prescribed three strength-endurance weekly sessions via the Edpuzzle platform. No significant intergroup differences were found (p>0.05). However, significant intragroup improvements in primary outcomes (muscle mass, p=0.002; corrected thigh and calf girths, p<0.05) were exclusive to the EG. Both groups showed improvements in secondary growth-related variables (height and sitting height) and fitness (cardiorespiratory capacity). Exploratory analysis revealed a potential doseresponse trend, with significant curl-up improvements only in students completing >4 weeks. Females reported higher platform usability (p=0.045) and satisfaction (p=0.037), while "lack of interest" was the primary dropout reason for both sexes. Therefore, while the program favored specific muscular adaptations, the lack of intergroup differences and low adherence suggest that natural biological maturation and the PE curriculum significantly influenced the results. The program’s impact should be considered limited, highlighting the need for more engaging to ensure sufficient exercise dosage in autonomous settings.