## 4 Discussion  
The results of our investigation revealed a correlation between the EXLD parameters and both RPE and RPE\({}_{\text{dur}}\). These results are in line with those from [PERSON] [55], where they found correlations between RPE and DIS, SPh, Acm, and DCm. Similarly, in another study, there was a correlation for DIS > 4 and ACh [37]. Of great interest are the results from [PERSON] et al. [39], where the load was calculated in arbitrary and individualized units and they found that SPm was correlated with both above-mentioned methods, but when it was expressed in individualized units, it was correlated only with SPvh. In another study on adolescents' football players, where the parameters were calculated in relation to the duration of the training (\"per minute\"), there were also correlations for TD, HSR, and Acm [36]. Similarly to our study, there are correlations between RPE\({}_{\text{dur}}\) and DUR, TD, DIS > 4, distance > 18 km/h, ACC, HMLD, and HSR [29; 37; 40; 41]. These correlations were stronger by using the individualized thresholds [39]. In semi-professional players, there is a correlation for TD [42], and in young football players for DUR, TD, ACC, and HSR [36]. Concerning the different durations of the microcyles, according to our study, in MIC5, all the parameters were correlated with RPE and RPE\({}_{\text{dur}}\) (except SPvh and ACh), as well as in MIC6, MIC7, and MIC9 (except ACh with RPE). An important finding is that all the correlations are of great magnitude with RPE\({}_{\text{dur}}\) in comparison to the RPE method. There is a lack of research in the literature about the relationship between these two methods and the EXLD in microcyles of different durations in professional football. Therefore, in microcyles of the same duration, most of the EXLD parameters have correlations with these two methods, and our study agrees with this for the microcyles of different durations [36]. Accelerations are very important in football [60; 61]; they have a correlation with RPE\({}_{\text{dur}}\)[36; 37], and the same goes for MIC6, MIC7, and MIC9, but not MIC5. A lack of correlations between wellness indicators and Acc (accelerations) and Dec (decelerations) is also reported in a recent study [47] that investigated the relationship between wellness and load during matches and training sessions in professional football players. Due to the limited number of days, MIC5 places emphasis on the players' recovery. The players use the first two days (MD+1 and MD+2) to recover from the previous match, while they use the last day for tapering. On MD-2, the load (e.g., accelerations) was limited, and this could possibly explain the lack of correlations with SPvh. [19]. Other studies found that there are stronger correlations between EXLD and RPE\({}_{\text{dur}}\) than with the RPE method and concluded that the first method is a more powerful indicator [36; 37]. Our results justify that the same phenomenon occurs in the different-duration microcyles. Another recent study in semi-professional athletes [46] did not reveal any difference between the two methods (RPE, RPEdur) in terms of their correlation with the EXLD. More specifically, positive correlations were observed between RPE and high-speed running distance, training duration, and sleep quality. The regression analysis for RPE showed that it can explain 31% of the variance, but for RPE\({}_{\text{dur}}\), it can explain 58%. This could be possibly explained by the fact that RPE underestimates the load provoked by running at moderate to high speed (>14.4 km/h) and high speed (>19.8 km/h), as between the high-intensity actions, there is an extensive recovery time (consisting of low-intensity actions) [41]. On the contrary, in another study, there were no differences between the abovementioned methods, but the magnitude of the relations was slightly elevated when the EXLD was adjusted by the individual fitness capacity of each player [39].