Internal load in elite young soccer players during a whole season according to playing positions

The aims of this study were 1) to compare the internal load, measured as session rating of perceived exertion (s-RPE), between training sessions and official matches among playing positions in young elite soccer players and 2) to analyze the s-RPE association between training and official match-play. Nineteen young elite soccer players who competed in the Spanish First Division Under-19 Championship participated in this study. Internal load was registered during 120 training sessions and during 30 official matches. Only the players who participated in all the weekly sessions and played at least 70 min were included in the further analysis. No significant differences (P > 0.05, ES = -0.57/0.62) among playing positions were found in the s-RPE registered by soccer players in training sessions, official matches nor in the total sessions. On the other side, higher s-RPE was observed during trainings in comparison to matches in each playing position (P < 0.001, ES = 5.51-30.77). However, no association was observed between training s-RPE and match s-RPE for the whole of the players (P = 0.60, r = 0.04), nor for each specific playing positions (P = 0.29-0.89, r = -0.11/0.16). These findings could be useful for coaches in order to plan the distribution of the weekly training load. Nonetheless, it is also suggested that internal load monitoring cannot be confidently used, in isolation, as a tool to detect differences in the matchplay demands, attending to playing positions, in young soccer players. Thus, the use of both internal (i.e., s-RPE) and external (i.e., global positioning system measures) load is suggested to manage the training and match load and to prescribe the training sessions appropriately