## 4 Discussion
The deltoid muscles, particularly the middle and posterior portions, play a crucial role in shoulder abduction and extension [18], respectively, while the upper trapezius assists in shoulder elevation and stabilization [19]. The significant rise in EMG\({}_{\text{RMS}}\) may indicate an increase in motor unit recruitment and firing rates within these muscle groups [20], likely due to the demand for sustained muscle activation to support the repetitive task. Additionally, the observed trend continuing beyond 50 shots to 100 shots emphasizes the persistence of neuromuscular adaptation over prolonged repetitive activities, highlighting the potential for muscular fatigue and overuse injuries if proper rest and recovery protocols are not implemented [21]. The observed differences in EMG\({}_{\text{RMS}}\) patterns between different muscular groups during shooting in fatigue conditions can be attributed to the varying functional roles and fatigue susceptibilities of these muscles. In the case of the infraspinatus and lower trapezius, the initial rise may reflect compensatory efforts by these muscles to maintain shooting performance as fatigue sets in, leading to increased muscle activation levels [22]. However, the subsequent decrease in EMG\({}_{\text{RMS}}\) could indicate a transition towards fatigue-induced changes, including impaired neuromuscular transmission and alterations in muscle contractility [23]. Conversely, the middle and posterior deltoid, along with the upper trapezius, exhibit a consistent increase in EMG\({}_{\text{RMS}}\) over time, suggesting ongoing motor unit recruitment and firing rate enhancement within these muscle groups [24], reflecting the demand for prolonged muscle activation to support the shooting motion. The persistence of this trend beyond 50 shots to 100 shots suggests the adaptability of these muscles to prolonged repetitive activities. Our study found no significant differences in the observed trends in EMG measurements between individuals practicing more than 100 shots per session and those practicing fewer shots. It is possible that the training routines did not significantly influence the final ability to cope with changes in fatigue conditions. This suggests that future training routines could benefit from a stronger focus on enhancing the ability to endure and cope with the intermittent muscular endurance required to sustain performance across repeated shots. However, the within-group analysis revealed more significant differences in the group with less than 100 shots per session, suggesting that training routines with fewer shots may expose athletes to greater variability in muscle fatigue patterns. One possible explanation could lie in the training specificity and adaptation. Athletes accustomed to higher shot volumes may have undergone physiological adaptations that enable them to better regulate muscle fatigue and maintain consistent performance over extended training sessions [25]. In contrast, individuals with lower shot volumes may experience greater variability in muscle fatigue patterns due to their inadequate adaptation to the demands of archery. Another factor to consider is the role of motor learning and skill acquisition. Athletes engaging in more frequent and intense training sessions may have refined their shooting technique to minimize energy expenditure and optimize muscle recruitment patterns [2], thereby mitigating the onset of fatigue. Conversely, those with fewer shots per session may exhibit less refined motor skills, leading to inefficiencies in movement execution and increased susceptibility to fatigue. The limitations of our study should be acknowledged when interpreting these findings. Firstly, our sample size was relatively small and may not have fully represented the diverse population of archers. Additionally, while we focused on EMG measurements, other physiological parameters such as muscle fatigue markers or kinematic data could provide a more comprehensive understanding of muscle activity during archery shots.