The Impact of Rational Warm-Up on Physical Preparation and Injury Prevention in Young Footballers: A Longitudinal...

Background/Objectives: One of the pillars of optimal footballer performance is the gradual preparation of the body for physical exertion in terms of intensity. The aim of this study was to evaluate the impact of a structured warm-up and cool-down program on flexibility, perceived fatigue, and injury prevention in young football players. Methods: Participants were 60 junior football players (U17), with a mean age of 16.5 ± 0.5 years, mean height of 172.5 ± 6.7 cm, and mean body mass of 70.2 ± 6.4 kg. The participants were assigned to experimental (EXP; n = 30) and control (CON; n = 30) groups during 8 mesocycles. A 4-week training stimulus was applied in parallel, consisting of an author-designed exercise routine with a profiled intensity (warm-up and cool-down parts) for the EXP group and standard exercises for the CON group. Selected variables (motor, endurance, injuries) were assessed before, during, and after the intervention. Additionally, the profile of selected correlations was analysed. Statistical analysis was performed using t-tests with a significance level set at p < 0.05. Results: In the EXP group (post-test), a significant improvement in flexibility was observed in the forward trunk flexion test (d = 1.13 cm; p < 0.001; d_c2 = 1.05). Simultaneously, participants reported lower levels of subjective fatigue (RPE = 6.86 ± 0.82 points) compared to the CON group (p = 0.016; d_c = 0.46) and demonstrated fewer injuries during the annual cycle (0.97 ± 0.83 vs. 1.33 ± 0.66; p = 0.026; d_c = 0.48). Both groups showed a strong negative correlation between flexibility and the number of injuries in the annual cycle, training experience and the number of injuries, as well as training experience and RPE (all r_p > -0.50). A strong positive correlation was found between RPE and the number of injuries (r_p > 0.60). Conclusions: The results demonstrate that the structured warm-up and cool-down program significantly improved flexibility, reduced perceived fatigue, and decreased injury occurrence in the participants.