# The Effect of Integrative Training Program on Youth Soccer Players' Power Indexes
## 4 Discussion  
The purpose of this study was to investigate the effects on anaerobic performance indicators of a brief INT training program in young soccer players (U15). The results showed that the intervention program improved performance in jumps and agility tests but not in speed and acceleration tests. So, the addition of a short-duration in-season INT program in U15 soccer players can induce positive adaptations in their performance. As previously mentioned, the intervention program improved the players' performance by 13.7% in the SJ and by 15.4% in the CMJ. These results align with earlier research. In particular, [PERSON] et al. [20] implemented an 8-week intervention program, involving three training sessions per week for U12 young soccer players and noted noteworthy enhancements in SJ by approximately 9.8% and in CMJ by \(\sim\)6.2%. Additionally, [PERSON] et al. [20] found that a neuromuscular training program applied twice a week for six months to U13 youth athletes improved jump performance. In a recent study, [PERSON] et al. [21] applied an intervention program twice a week for 12 weeks to U9 soccer players, observing improvement in CMJ at 6 and 12 weeks compared with the initial measurement. It is known that the stretch-shortening cycle affects jump performance [14; 20], and the improvement observed in SJ and CMJ in this study may be attributed to the impact of the INT program on the efficiency of the stretch-shortening cycle of the participants [20]. Previous studies have also reported that SJ performance depends on concentric contraction [21], the mytotic reflex, and the ability of muscle fibers to store elastic energy during the stretch-shortening cycle [22]. Furthermore, improvement in intermuscular and intramuscular coordination and tendon stiffness are factors that can influence jump performance [32; 33]. However, there are studies that did not observe changes in jump performance after an 8-week neuromuscular training program. Specifically, the study by [PERSON] et al. [23] conducted in elite youth soccer players (U19) attributed the lack of adaptations to the low training volume and the high level of the athletes. As mentioned above, the level of participants and the different characteristics of the intervention programs (training volume and intensity, duration, density, and type of exercises) lead to different results and make comparisons of studies more difficult. Figure 3: Performance changes in (**A**) 10 m, (**B**) 30 m, and (**C**) Illinois agility test. * denotes a significant difference with Pre (\(p<0.05\)). EG, exercise group; CG, control group. In the present study, no significant changes were observed in the acceleration and speed of the soccer players in both groups. The findings of this study are consistent with those of previous research. Specifically, [PERSON] et al. [34] investigated the impact of a combined strength and pylometric program. The program was applied for 8 weeks to U19 soccer players, and they observed that their performance in the 10 m and 20 m sprints did not improve. Additionally, [PERSON] et al. [22] did not observe any changes in the performance of players in the 10 m and 30 m sprints. Furthermore, [PERSON] et al. [23] did not observe changes in sprint performance. In contrast, several studies report improvements in performance [14; 21; 35]. [PERSON] et al. [36] applied a strength/plyometric intervention program, and the results showed improvement in sprint performance in adolescent soccer players. Additionally, [PERSON] et al. [35], in their study, implemented a strength program to improve power over two years in developmental age soccer players (U15, U17, and U19) and observed improvement in sprint performance. The lack of adjustments in acceleration and speed observed in this study is believed to be due to some factors associated with the intervention program. More specifically, the duration of the program was short, as was the total number of workouts (n = 10).