## 4 Discussion
This study also showed a greater intra-group effect size for the RT when compared to either PLY or CG groups. Post hoc testing showed improvements in knee flexor peak torque in all groups pre- and post-training. However, the greatest improvement was achieved in the RT group (from 125.3 to 143.3 Nm). The next variable was the value obtained of 1 Rm in the back squat where it was significantly higher in the RT compared to the CG group (\(\pm\)24.9 kg) and PLY group (\(\pm\)41.8 kg). To conclude, the value of 1 RM in the squat was improved in each group. However, in the next paper, the authors stated that the motor performance of soccer players seems to be more effectively associated with variables that are measured within the power-training load range at which peak power is obtained. The peak power of highly trained soccer players was shown to occur with loads of 45% and 60% 1 RM during jump- and back squat exercises, respectively. [50]. [PERSON] et al. [51] assessed the effects of velocity-based resistance training on strength, aerobic power, and acceleration. Two under-19 Spanish soccer teams completed a 16-week resistance training program followed by strength and power evaluations. The study participants were subjected to two evaluations, before and after the training intervention, where CMJ and CMJ20, Smith machine speed movement (FSL) (20, 30, 40 kg), acceleration capacity at various split times, and MAS were evaluated. Loads used by each player were individually determined according to the results of the initial test. The athletes trained at a bar speed of 1 m/s in the back squat, which corresponded to approximately 55% of 1 RM. Overall, Team A improved in the CMJ tests by (5%), strength, and speed tests of the back squat at 20, 30, and 40 kg loads. Additionally, the team's maximum aerobic speed was significantly improved. We believe that the evaluation of our research should take into account, in addition to % 1 RM (50-60%) or VBT (1-0.75 m/s), the duration of the intervention (4-week mesocycle). In this manner, we agree that adaptive changes to resistance training are generally evident after 8 to 12 weeks. However, some studies have observed increases in muscle strength after 2-4 weeks [52]. The primary argument is that this early increase in strength is likely due to neuromuscular and connective tissue adaptations, whereas the early increase in muscle CSA (cross-sectional area) size may be the result of edema [53]. An important factor that had a significant impact on the results of our study was the movement tempo and TUT. The main issue of our periodization included the extension of the eccentric phase of movement in particular exercises performed with a load of 50-60% 1 RM. This selection is optimal for power development, but we wanted to avoid submaximal and maximum loads (85-100% 1 RM) on the other hand, assuming that extending the eccentric phase of movement could cause excessive muscle damage and delayed muscle soreness (DOMS) [54]. The appearance of DOMS in players in the pre-season could significantly affect their effectiveness in technical and tactical activities during soccer training and increase the risk of injury through micro-damage to muscle fibers. In our study, we considered the extension of tempo in the eccentric phase with an appropriate supercompensation during the intervention mesocycle. At a given load, the movement tempo variation was a consequence of an immediate change in TUT (time under tension) and in consequence a change in total training volume affecting muscle strength and power [6; 55; 56]. [PERSON] et al. [57] compared eccentric muscle contractions and showed several distinct physiological properties as compared with concentric actions. For example, different neurological patterns have been observed between these two types of muscle contractions. Compared with concentric contractions, eccentric ones are characterized by a broader and faster cortical activity as movements are being executed.