## 4 Discussion
### Physiological Responses to OCR  
The study showed that both the 5 km and 13 km OCR significantly affected various physiological parameters. The observed decrease in leg strength and urine pH, coupled with increased blood lactate and perceived exertion, highlights the significant physiological demands of OCR events. The positive correlation between pre-race body temperature and performance, as well as post-race thermoregulation, underscores the importance of proper preparation for heat management in OCR athletes. One of the main purposes of this study was to analyse the physiological response in OCR. We found a significant decrease in the leg's strength after the race in both Sprint and Super distances, supporting data from previous research in half-mountain marathons [32]. This fact may be related to the increase in metabolic demands that produce a higher anaerobic metabolism activation and then a higher blood lactate concentration, a fact related to a decrease in the ability to produce force [32; 33]. In this line, both races presented a decrease in urine pH, as well as an increase in urine glucose, protein, and color, a fact that corresponds to intense exercise [34] and dehydration status [35]. In the Super distance, the Fev1 decreased after the race, probably because of the fatigue of the respiratory muscles, since it has been seen in the literature that both diaphragm and intercostal muscles involved in the breathing mechanics can be exhausted after extenuated aerobic exercise [36]. Regarding the injury tests, we observed that lower limb stability in a single leg stance decreased after the long course in both feet, a fact in which fatigue has a direct impact [37]. Contradictory evidence exists in this area since previous studies postulated that these changes occur because of neuromuscular failure at the ankle complex prior to hip muscles [38]. Others demonstrated that hip muscles are responsible for the lack of stability due to fatigue [39]. The stability or instability of the lower limbs may depend on the physical conditioning of the athlete, with either ankle or hip joints potentially being responsible. In the Sprint distance, participants with lower pre-race heart rates achieved better performance, showing the importance of cardiovascular fitness in this OCR distance. Also, the higher pre-body temperature and the post-lower body temperature were correlated with probe time, demonstrating the relationship between good thermoregulatory capacities and performance in OCR. In this line, the first participants to cross the finish line had higher blood lactate concentrations, and lactate tolerance was presented as an important key factor in OCR performance. The urine \(\Delta\)pH is also an indicator of exercise intensity, and we found that faster athletes presented a higher decrease in pH, a fact that also supports the idea that a better workout capacity in an acidic environment provides better performance. In both distances, higher values in isometric handgrip strength pre- and post-exercise correlate with performance. Specific grip muscle training, as well as climbing training for suspension obstacles, would improve OCR performance. In this line, participants with higher pre-leg strength also achieved higher performance in both distances, supporting previous research in which pyometric training improved both jump height and running performance because of the improvements in running economy and muscle and tendon stiffness factors [40]. In the Sprint distance, post measurements of leg strength correlated negatively with probe time, but in the Super distance, this correlation was positive. We could explain this phenomenon since, in a long course, dehydration and neuromuscular fatigue are higher because of the time required to complete the race [41]. In both courses, spirometry values pre- and post-race presented a large positive correlation with performance, which supports previous evidence showing the relationship between selected lung capacities and performance in running performance [42].