## 4 Discussion  
The purpose of this study was to quantify the specific demands of external load in semi-professional soccer players by examining relative thresholds based on individual capacities and observing significant differences in speed and acceleration profiles according to playing position. The high variability in activity patterns within the team and between positions underscores the need for an individualized approach to monitor external loading and the need for specific physical training to prepare players for the specific demands of each playing position [14; 32; 35; 60]. **Fullbacks**  
Despite being the position with the highest maximum speed, at 33.3 km/h, fullbacks were the players with the least total distance, distance at moderate intensity, and distance at high intensity. For very-high-intensity distance (or sprinting), they were second only to the CDs, but they did not outperform any other playing position significantly. Interestingly, their sprint number in zone 5 was among the lowest, which does not match the distance covered in this zone. This could be explained by the fact that FBs start very-high-speed actions from behind and accumulate large sprint distances but perform few such actions. In both distance and number of accelerations of both intensities and from any starting speed, they were the players who accumulated the least acceleration activity throughout the week. These findings disagree with the current literature that describes FBs with high-intensity activity and a large number of sprints and accelerations [61; 62; 63]. One possible explanation is the inclusion in our study of training sessions when most studies focus only on matches. Therefore, the demands of training sessions for FBs might not reflect the demands of matches. In addition, FBs are usually players with high physical capacities, and the absolute thresholds used in the current evidence overestimate their abilities [45; 64]. **Central Defenders**  
Being the second-slowest position with a Vmax of 31.5 km/h and with the lowest maximum acceleration capability from running with 3.48 m/s\({}^{-2}\) and from standing next to MF (6.21 m/s\({}^{-2}\)) with 6.23 m/s\({}^{-2}\), CDs were one of the positions with the highest very-high-speed distance and acceleration activity, with the highest total distance accelerating at high intensity and the greatest distance and number of accelerations with moderate intensity from standing and running. There is a trend in the scientific evidence which  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Initial Velocity**} & **Central Defender (CD)** & **Fullback (FB)** & **Midfielder (MF)** & **Wide Midfielder (WMF)** & **Forward (FW)** & **One-Way ANOVA (F/Df; \(p\)-Value)** \\ \hline Number of accelerations (\(>\)75\% (>\)75\% (\(>\)75\% (\(>\)75\% (\(>\)75\% (\(>\)75\% (\(>\)75\% (\(>\)1.37;\(2.57)\% (\(>\  
describes CDs as the position with the lowest intensity in both speed and acceleration profiles [38; 44; 63]. In a recent study, CDs turned out to be the position with the highest values in acceleration variables [45]. Today, the physical characteristics of CDs are not clear. A possible explanation without entering the assessment of contextual variables is the fact of underestimating the physical capacity of CDs using absolute thresholds. Our results showed a low physical capacity of Vmax and maximal acceleration from 0-7 km/h or 7.1-14.3 km/h, and this was where they performed better than the other demarcations. **Central midfielders**  
This was the position with the lowest maximum speed at 30.7 km/h and with the lowest maximum acceleration capability regardless of initial speed. Significantly, it was the position with the largest total distance, with more distance at moderate and high intensities, more sprinting, but with less very-high-intensity distance.