Performance Modifications Following 8 Weeks of Strength and Strength–Power Resistance Training in Adolescent Track and Field Athletes

Background: Strength and the strength–power continuum may increase athletic performance, although data are scarce regarding the effects of long-term periodized training on the athletic performance of adolescent track and field athletes. The purpose of this study was to investigate performance modifications following 8 weeks of strength and strength–power resistance training, focusing on the athletic performance of adolescent track and field athletes. Methods: Following an equivalent single-arm pre–post intervention design, 16 adolescent athletes (age: 16.3 ± 0.5 years; mass: 56.5 ± 10.4 kg; height: 1.67 ± 0.07 m) participated in the study. Athletes followed an 8-week periodized resistance training program aiming to increase strength and strength–power. Measurements were performed before (T1), at the middle (T2) and at the end of the training period (T3) and included the standing long jump, single-leg standing long jump, five-step long jump, seated medicine ball throw, 0–80 m sprint and 1RM in the bench press and parallel squat. Results: The standing long jump (F(2,14) = 109.564; η2 = 0.940; p = 0.001), single-leg long jump (F(2,14) > 41.801; η2 = 0.857; p = 0.001) and five-step long jump (F(2,14) = 148.564; η2 = 0.955; p = 0.001) improved significantly from T1 to T2 (p < 0.001) and from T2 to T3 (p < 0.001). The seated medicine ball throw (F(2,14) = 124.305; η2 = 0.947; p = 0.001) and sprinting performance (F(2,14) = 51.581; η2 = 0.828; p = 0.001) were significantly enhanced from T1 to T2 (p < 0.001) and from T2 to T3 (p < 0.001). The 1RM in the bench press (F(2,14) = 36.280; η2 = 0.838, p = 0.001) and in the parallel squat (F(2,14) = 48.165; η2 = 0.873, p = 0.001) increased significantly from T1 to T2 (p < 0.001) and from T2 to T3 (p < 0.01). Conclusions: Strength and the strength–power continuum appear to have a positive effect on the physical fitness of adolescent track and field athletes, which highlights the importance of strength-based resistance training programs in adolescent athletes.