## 4 Discussion
The researchers attributed this to the more efficient functioning of the circulatory system (transportation of gases, nutrients for energy production, ad removal of derivatives of biochemical reactions) as in the same task, the circulatory system of the control group worked harder (more heart beats) to produce the same work. Regarding the running performance indicators of the soccer players in the present study, no significant difference was found between the two conditions or between the halves. In one of the studies that used soccer matches to evaluate the effect of an RW program on sprinting, [PERSON] et al. (2004) [2] found that after passive rest, sprint performance decreased, while after RW, performance was unchanged. In another study ([PERSON] et al., 2014) [16], the researchers observed that in both conditions, the total distance covered by the soccer players in the first quarter of the two halves decreased (RW: 9% and CON: 4%). They also reported that there were no differences in distances covered at high intensities both between conditions and between halves. The findings of the present study have several elements in common with those of [PERSON] et al. (2014) [16]. However, it should be mentioned that the limited number of matches we used for the study (two in each condition) and the other studies (one match/condition) do not allow us to draw safe conclusions. For example, [PERSON] et al. (2014) [16] stated that the reduced running performance may be due to the increased possession of the ball that the RW team had in this match. It is also known that running performance in a match can depend on the dynamic of the opposing team, possession of the ball [32,33], formation [34], and weather/terrain conditions [35]. Even when talking about running performance comparisons, we should talk about effective playing time. More specifically, in a previous study [36], it was reported that in the first quarter of the first half, the effective playing time was 40 s/min, while in the first quarter of the second half, the corresponding time was 36.5 s/min. From this, we can understand that in order to make any comparison, we should refer to the same effective match time of play or talk about relative values, e.g., distance/minute. [PERSON] et al. (2014) [16] refer to this issue as in their study they observed \(\sim\)10% less effective playing time in the second half compared to the first. They then calculated the running distances of the second half proportionally and reported that the soccer players showed greater running performance in the second half. However, this calculation involves a high risk of error. As mentioned above, the primary goal of the application of RW is to keep the body temperature high or limit its decrease as much as possible. It has been reported in previous studies that high body temperature can accelerate anaerobic energy production (e.g., phosphocreatine hydrolysis) [37] by activating glycolytic enzymes [38] to produce ATP and improve cross-bridge cycling [37]. Furthermore, increased body temperature can enhance the transmission of nerve impulses and the speed of muscle contraction [39,40]. Thus, the differences that appeared between the two conditions (P (15 min) and 3 min RW) in some of the performance tests may be due to the maintenance of a higher body temperature. In conclusion, in the present study, it was observed that a short half-time RW program can limit the decrease in body temperature and the speed and jumping performance of young soccer players. However, no changes were observed in running performance during the matches as there are many factors that can affect this performance such as team tactics, the opposing team, etc.