# Impact of One Additional Substitution on Player Load and Coaching Tactics in Elite Football
## 8 General Discussion  
In line with recent studies, our findings support the idea that an additional substitution would benefit the game [2; 28; 29]. The assessment of an additional substitution in regular time clearly indicates the potential for load reduction and an increase in the tactical influence of the coaches on the match. The benefits for the match day squad (including substitutions) were proven by an increase of the load reduction of 50%, and this value could be significantly increased if the substitutions were focussed on key players. The average time of the completion of the fourth substitution is at 81 min, with a utilisation rate of 70%. Therefore, coaches could take their key players off the field once the match has been decided, which will, in turn decrease the players' load, and therefore, increase their recovery time and potentially their future performances. However, the results of the two studies also show that the recent adoption of an additional substitution in extra time does not sufficiently fulfil the objective of reducing the load on players in a match, tournament, or season (see Table 11). While the added substitution definitely has the potential to reduce the player load crucially, the practical implementation showed that the coaches use this option too late in the games. Nevertheless, the coaches assessed the additional substitution in extra time as beneficial for load reduction in a game but acknowledged its limitations for an entire season. As mentioned above, previous research and coaches' responses in the survey indicate this was caused by the course of the match events. Contrary to an additional substitution in regular time, the first three substitutions would not be used earlier if the additional substitutions were only granted in extra time. Based on the average timing of substitutions, especially the third substitution in adult football, substitutions are not optimally used to optimise regeneration. According to [PERSON] and [PERSON] [38], the recovery times of elite football players were about 89% longer in the last 15 min than in the first 15 min of a match, which results in a shorter recovery time for players who were substituted earlier. While this temporary fatigue may be caused by different physiological factors and not only by accumulated fatigue, it indicates that particularly late substitutions may not be beneficial in terms of player load reduction and recovery. While these findings indicate that frequent substitutions can help maintain the health of athletes through squad rotation [28; 29], other factors should not be neglected. As already mentioned, the amount of load players experience in relation to their rest time must be considered, especially among the national team players [30; 31; 32]. Therefore, it is critical to consider other variables such as the intervals between matches as well as the rest intervals between physical exercises while managing player load. However, while it is possible to regulate the intensity and load during training exercises, it is virtually impossible to do so in the matches. In such a scenario, additional substitutions offer the potential to better manage player load distribution even during matches. When evaluating the dataset, it stood out that a high number of the possible substitutions was actually used. Nearly all (95%) of the possible substitutions in the Bundesliga were completed, and in 88% of the matches, all three substitutions were made, which points out to the necessity of the current rule. In line with the previous evaluations of the timing differences between matches with a substitution contingent of two and three [9], an increase in the substitution contingent would result in substitutions being made earlier and more frequently in the match. Even though only 70% of the fourth substitutions were used, the data still indicate that an additional substitution actually leads to a higher utilisation rate of the currently allowed three substitutions.