Abstract
Background/Objectives: This longitudinal randomized controlled study aimed to evaluate the effects of an integrative neuromuscular training (INT) intervention on strength and speed measures in Spanish students across different age groups. Methods: A total of 121 students, aged 11-12 (G1) and 15-16 (G2), were randomly assigned to four groups: two experimental groups, G1exp (n = 30) and G2exp (n = 31), and two control groups, G1con (n = 30) and G2 (n = 30). Experimental groups participated in two 20 min INT sessions per week for four weeks, focusing on physical literacy (agility, coordination, balance, and speed) and a resistance training program, integrated into the first part of physical education classes (PEC). Results: Experimental groups showed significant improvements (p < 0.001) in lower-body power (G1exp: t = -7.04; d = -1.30; G2exp: t = -5.19; d = -0.91), upper-body power (G1exp: t = -5.94; d = -1.10; G2exp: t = -3.52; d = -0.62), abdominal endurance strength (G1exp: t = -9.72; d = -1.80; G2exp: t = -4.75; d = -0.84) and sprinting (G1exp: t = 5.22; d = 0.96; G2exp: t = 5.90; d = 1.04). A comparison by age groups revealed significantly greater improvements in upper-body power in G1 vs. G2 (t:-2.83; p = 0.02). Conclusions: A four-week INT program implemented at the start of PE classes can improve strength and sprint performance in youth across all ages. We recommend incorporating INT into the first part of physical education sessions to contribute to meeting the physical activity, well-being and conditioning needs of young people.