Effects of Combined Training on Physical Fitness According to Maturity in Male Youth Soccer Players

Abstract Zghal, F, Colson, SS, Bouzid, MA, Elloumi, M, Laurencelle, L, Behm, DG, Granacher, U, and Chaouachi, A. Effects of combined training on physical fitness according to maturity in male youth soccer players. J Strength Cond Res XX(X): 000–000, 2026—The aim of this study was to investigate whether the adaptations related to combined resistance and plyometric (PLYO)/sprint training on measures of physical fitness differed according to maturity status. Thirty-five young male soccer players were assigned to 2 experimental groups, labeled circa-peak-height-velocity [PHV] ( n = 13, age 14.2 ± 0.2 years, predicted from/to age at PHV [PAPHV] = +0.1 ± 0.3 years) and post-PHV ( n = 12, age 17.2 ± 0.4 years, PAPHV = +2.9 ± 0.5 years), and an active control group (CONT; n = 10, age 15.8 ± 1.7 years, PAPHV = +1.1 ± 1.3 years). Two weekly sessions of combined resistance training and PLYO/sprint training, or soccer training sessions, were added to the regular soccer-training program for the experimental and CONT groups, respectively. Before and after 7 weeks of training, absolute peak torque, peak torque normalized to thigh volume, and absolute and relative (normalized to peak torque) rate of torque development (RTD) during maximal voluntary isometric contraction of the knee extensors were assessed. In addition, vertical jump (squat [SJ], countermovement [CMJ], drop jump [DJ]), linear sprint (5, 10, 20 m), and change-of-direction (CoD) speed tests (505 test) were performed. An analysis of covariance with group as between-subject comparator and baseline data as a covariate was computed using delta values. Significant differences were observed for absolute peak torque ( p < 0.001; η 2 = 0.62), peak torque normalized to thigh volume ( p < 0.001; η 2 = 0.58), absolute RTD ( p < 0.001; η 2 = 0.64), and relative RTD ( p < 0.01; η 2 = 0.26), vertical jump performance (SJ: p < 0.001; η 2 = 0.54, CMJ: p < 0.001; η 2 = 0.66), and linear sprint (5-m: p < 0.001; η 2 = 0.55, 10-m: p < 0.001; η 2 = 0.36) and CoD speed ( p < 0.001; η 2 = 0.41) with greater percentage changes for the circa- compared with the post-PHV group. Our results suggest that the extent of adaptations to combined resistance and plyometric (PLYO)/sprint training is influenced by the individuals' maturity status. From a practical perspective, the findings of this study suggest that combined resistance and plyometric/sprint training could be particularly useful when performed around PHV, a maturational status at which greater neuromuscular adaptability may enable further gains in physical fitness.