High-intensity interval training improves the reactive strength index and motor ability of youth football players

Abstract

Background: The aim of this randomized controlled trial was to determine the effects of a four-week running-based high-intensity interval training (HIIT) intervention on the reactive strength index (RSI) and motor abilities in youth football players. In this context, the contributions of the running-based HIIT protocol HIIT protocol, implemented in addition to regular football training, were evaluated on performance indicators such as speed, back strength, change of direction (COD), and countermovement jump (CMJ). This study aims to contribute to the development of scientifically grounded training programs to support performance improvement in youth football players. Methods: A quantitative research design was employed in this study, specifically a randomized pretest–posttest controlled experimental design. Twenty male youth football players, aged 11–13 years, who voluntarily participated in the study were randomly allocated to either the experimental group (EG; n = 10) or the control group (CON; n = 10). The EG participated in a running-based HIIT program three times per week for four weeks by replacing a low-to-moderate-intensity technical–tactical segment of their regular football training, whereas the CON continued with only regular football training during this period without any additional training volume. The players underwent RSI, 10 m, 20 m, and 30 m sprint tests, back strength tests, the Illinois Agility Test, and CMJ tests both before the training sessions and at the end of the four-week intervention. Results: According to the repeated-measures ANOVA results, pretest values did not differ significantly between the groups (p >.05). Over the 4-week period, significant improvements with large effect sizes were observed in RSI, sprint performance (10, 20, 30 m), back strength, COD, and CMJ tests (p