# Stability of Running Stride Biomechanical Parameters during Half-Marathon Race
## 4 Discussion
A more granular examination of LSS values across the race's four segments (11.28 \(\pm\) 1.31 kN/m for the first segment, 11.21 \(\pm\) 1.31 kN/m for the second, 11.11 \(\pm\) 1.23 kN/m for the third, and 11.10 \(\pm\) 1.28 kN/m for the fourth) reveals a trivial decline as the race progresses, without statistical significance. However, although the changes in LSS between stages 1 and 2 were statistically significant, the absolute magnitude of this difference was very small (0.07 kN/m), and the effect size was also small (\(\eta^{2}\) = 0.004), suggesting a limited practical impact. Looking at the broader picture across all four race stages, the overall decline in LSS is quite limited and may not necessarily be indicative of substantial muscular fatigue. The relatively stable values of LSS across the race segments could be interpreted as the athletes effectively managing and compensating for fatigue through their highly trained capabilities, resulting in minimal disruptions to this biomechanical parameter. In the analysis of VO, this study did not reveal any statistically significant differences (\(p\) = 0.87) with notably small effect sizes (\(\eta^{2}\) = 0.002), indicating a stable trend across the evaluated metrics. These non-significant differences can be explained through previous research [9; 10] that highlighted that, although VO can increase with fatigue, changes in this biomechanical parameter are minimal, and that this could lead to an increase in oxygen consumption. [11]  
In the analysis focused on SL, comparative research involving trained ultramarathon runners over a duration of 6 h highlighted a decrease in SL from 1.30 m at the race's commencement to 1.10 m under conditions of fatigue [7]. Contrarily, the current study's investigation into half-marathon performance did not manifest significant differences (\(p\) = 0.35), with effect sizes remaining minimal (\(\eta^{2}\) = 0.001) across all race segments. Given that the subjects of both studies are trained runners, the observed disparity in SL alterations could potentially be attributed to the significantly shorter average competition time of the half-marathon 1:23:34 \(\pm\) 00:10:12 (h:m:s) compared to the extended 6-h timeframe of the ultramarathon. This variance in race duration might offer insights into the findings from another study, which observed that half-marathon runners finishing between 80 and 90 min exhibit an SL of approximately 1.42 \(\pm\) 0.09 m [14], closely aligning with the 1.43 \(\pm\) 0.01 m SL measured for athletes in the current study. This parallel suggests that the race duration and intensity could significantly influence SL dynamics, emphasizing the need for further exploration into how different race conditions impact biomechanical parameters among endurance athletes. This study acknowledges certain limitations that warrant mention and highlights avenues for forthcoming research directions. Firstly, the small sample size and the homogeneity of the participant pool, consisting solely of male athletes from a single training group, may limit the generalizability of the findings. Future studies could benefit from a larger, more diverse cohort to explore the biomechanical impacts of fatigue across different populations, including female athletes and those with varying levels of training and competitive experience. Additionally, while the naturalistic setting of an official half-marathon provides valuable insights into real-world performance, it also introduces uncontrollable variables that may affect the results, such as individual pacing strategies and environmental conditions. Subsequent research could aim to isolate these factors or examine their specific contributions to the observed biomechanical patterns. Moreover, the focus on a flat half-marathon course limits the applicability of the findings to races with different profiles, such as those with significant elevation changes.