## 4 Discussion
Later, despite continued increases in muscle activity, neural-muscular coupling remains stable, indicating a complex adaptation process [32]. Additionally, research has shown that during fatiguing contractions, there is a unique modulation of synaptic input from Ia afferents to antagonist motor neurons, suggesting separate control mechanisms for agonist and antagonist muscles. This modulation reflects the CNS's ability to adjust muscle activity to compensate for fatigue-induced changes, ensuring the maintenance of net torque and functional performance [33]. These findings highlight the complexity of neuromuscular adaptations under fatigue, indicating that the CNS employs dynamic strategies beyond the traditional \"common drive\" theory. The reduction in antagonist coactivation observed post-fatigue may serve to optimize force production by the agonist muscles, thereby sustaining performance despite the onset of fatigue. Understanding these mechanisms is crucial for developing interventions aimed at enhancing motor performance and preventing fatigue-related injuries. Despite the insights provided by this study, several limitations should be acknowledged. First, the fatigue protocol employed was short term and conducted under controlled laboratory conditions, which may not fully replicate the prolonged or repetitive fatigue experienced during real-world running scenarios. This limits the generalizability of the findings to endurance running or outdoor conditions. Additionally, our fatigue protocol was performed on a treadmill under uniform conditions, whereas real-world running includes variable terrains, environmental factors, and pacing strategies, which may elicit different fatigue responses. Future studies should consider incorporating field-based assessments or more ecologically valid fatigue protocols to better reflect real-world running conditions. Second, this study exclusively recruited young, healthy male participants with a specific BMI range and regular running habits, which limits the applicability of the findings to broader populations, including females, older adults, or individuals with varying physical profiles. Given that sex, age, and training background can influence neuromuscular fatigue and biomechanical responses, future research should examine more diverse populations to enhance the generalizability of these findings. Third, the measurements were taken immediately after the fatigue protocol, providing a snapshot of fatigue-induced changes but not accounting for the dynamic progression or recovery of fatigue over time. A longitudinal assessment could offer deeper insights into the temporal effects of fatigue on neuromuscular and biomechanical adaptations. Fourth, this study focused primarily on kinematic and kinetic changes in the sagittal plane, potentially overlooking critical adaptations in the frontal and transverse planes, which are important for stability, injury risk, and load redistribution strategies. Future research should include three-dimensional biomechanical analyses to provide a more comprehensive understanding of multi-planar adaptations to fatigue. Lastly, while surface electromyography (sEMG) provided valuable information on muscle activation patterns, it is limited to superficial muscles and is prone to signal interference, such as cross-talk and variability in electrode placement. Incorporating advanced techniques, such as fine-wire EMG, musculoskeletal modeling, or high-density EMG, could provide a more comprehensive analysis of muscle coordination and joint-specific compensatory mechanisms.