## 4 Discussion
Therefore, caution must be exercised when comparing studies, as variations in threshold levels and sensor technologies can result in varying measurement errors and HAE incidence. The clinical significance of these lower-magnitude headers in soccer players is not yet fully understood [23]; however, it is thought that chronic exposure to sub-concussive impacts may increase the risk of neurodegenerative diseases [6]. One study found that professional football players were 3.5 times more likely to die from neurodegenerative diseases, including a 5.1 times higher risk of dying from Alzheimer's disease and a 4.3 times higher risk of dying from motor neuron disease [50]. However, other studies have not found a clear correlation between heading exposure and adverse outcomes [19; 51]. It is important to note that prior studies have often quantified heading exposure through self-reported questionnaires or controlled laboratory environments, which may not accurately reflect the range and magnitude of headers experienced in competitive game contexts [6]. This study did not evaluate the potential relationship between biomechanical measures and neurocognitive clinical outcomes, but it could be the focus of future studies. By eliciting the effects of repeated sub-concussive impacts on neurocognition, we may begin to understand the risk of concussion beyond peak kinematic values alone. This study provides valuable insights into the correlation between header kinematics and the contexts in which they occur; however, it is important to note certain limitations. This study only included male soccer players participating in a university intra-mural football league, so the characterizations of heading scenarios provided herein may not be generalizable to other cohorts. Additionally, the study only examined competitive matches, and future research should include HAEs during training sessions to obtain a more comprehensive understanding of HAE kinematics. The methods used to measure heading-related exposure (PLA and PAA) have certain shortcomings, specifically in terms of not considering the direction and time duration of head kinematic signals, which could be crucial in determining the degree of brain tissue deformation from a HAE [22; 52; 53]. Although custom-fit mouthguards were used, further research is needed to investigate the influence of mouthguard fit on head kinematic measurement error [29]. The sample size of 10 players from a single college during a season of play is relatively small, and therefore the purpose of this study was not to report incidence/exposure metrics. To develop effective player protection recommendations, future studies should capture kinematic data from both matches and training sessions across a large cohort of male and female athletes and different levels of play. Our analysis revealed a lack of adherence to mouthguard use, with an average of only 2.8 players per match wearing them, with many not using them for the entire match. Previous research has shown that soccer players are among the least likely to use mouthguards despite their effectiveness in preventing orofacial injuries [54]. A study by Collins et al. [55] found that players commonly cited discomfort, lack of coaching instruction, and difficulty breathing as reasons for non-compliance. Despite the development of custom-fitted mouthguards having largely eliminated these issues, usage still remains low [56]. To address this, efforts should focus on educational initiatives. Previous research has shown that 78.3% of athletes were unaware of the benefits of mouthguard use, and 97.1% of these athletes had never used a mouthguard [57]. Coaches and athletic trainers can play a crucial role in increasing mouthguard use by educating athletes about the importance of brain injury research, holding them accountable for their behavior, and reducing stigma in making healthy choices [54].