## 4 Discussion
### Overall Injuries  
The results of the analysis of the differences in the incidence of all injuries, between the entire season and the time immediately after the coaching changes at the club, suggest a general increase. Although these differences did not reach statistical significance, likely due to the limited sample size, the medium effect size for the 4 weeks after the change indicates a potentially significant negative impact of coaching shifts on players' health. These findings are in line with the prevailing opinions of football coaches and practitioners, but also with previous studies on this topic [2,18]. Unlike previous studies focused on specific injury types such as hamstring strains or general muscle injuries, this study analyzed the overall injury incidence and the player's perspective concerning availability [2,18]. Total injuries increased substantially following coaching changes, which is in partial alignment with previous observations of the transitional period. The dataset is inclusive of all injury types, whether contact or non-contact, suggesting multifactorial relations between tactical changes, changed physical load and psychosocial factors can complexly interact and affect injury occurrence. Although it was not directly measured here, this is in accordance with previous studies on this topic [2,23]. This suggests a more nuanced relationship among tactical shifts, loading changes, and psychological stressors. As an example, a study by [PERSON] et al., 2023 focused specifically on hamstring muscle injuries and found that organizational instability, i.e., changes in coaches, medical staff, fitness coaches, and other staff members, caused an increase in injury burden [2]. The most obvious reason for this phenomenon can be found in the change in training methodology implemented by the new head coach. Specifically, in the desire to achieve an instant change in tactical aspect, atmosphere, approach, and consequently the result, new coaches often increase the frequency and intensity of training [17]. This can easily lead to disruption of the load monitoring process, especially if the change in head coach is accompanied by a change in fitness coach, which [PERSON] et al. point out in their study. The relationship between training load and injuries has recently been extensively studied, and many studies have linked the effect of acute and chronic load and sudden load spikes to which players are not adapted, with an increased injury risk [12,24,25,26]. Although this study is observational and does not directly investigate the causal interference of individual training factors with injuries, we can assume that coaching changes caused changes in the training process, and thus influenced the occurrence of injuries. This may also relate to a change in routine and implementation of prevention strategies that were established at the club under the previous staff [27]. Future studies should use load monitoring to better understand the causal mechanisms between coaching changes and injury incidence. In addition to this, certain psychological factors could have increased the risk of injury in the period following coaching changes. Although not directly measured, informal observations by experienced practitioners, supported by peer-reviewed literature, suggest that psychological stress during coaching transitions could influence injury risk [28]. Namely, in such situations, players are uncertain, fearful of their place in the squad, and feel the pressure of proving themselves again to the new coach [28]. This can lead to increased fatigue, impaired cohesion and communication in the team, and uncontrolled motivation and aggressiveness in the training, which can result in a higher number of contact injuries [28]. However, this remains speculative and outside the scope of the present study. It is also important to note that the injury incidence in this study is somewhat higher than is typically reported at the elite level of football.