The Performance in 10 km Races Depends on Blood Buffering Capacity

For long time running speed related to ventilatory threshold has been considered a strong predictor of running performance ranging from 5 km running to marathon. Specifically for 10 km race, is already known that runners are able to sustain the entire race above it. However, there is no comparison between 10 km performance and running speed related to respiratory compensation point not even about pacing strategy or information regarding acid-base status at this exercise intensity. Objective: We have investigated the relationship between 10 km performance time trial (s10km) and running speed related to ventilatory threshold (sVT) and to respiratory compensation point (sRCP), the pacing strategy related to these intensities and blood acid-base response during four different constant running speeds. Methods: Twelve male amateur (age-37.3 ± 7.2 years; height-171.9 ± 9.4 cm; weight-65.6 ± 10.1 kg; 10 km performance-13.4 ± l1.4 km.h-1) and nineteen elite (age-27.7 ± 9.9 years; height-171.7 ± 7.2 cm; weight-54.7 ± 62.2 kg; 10 km performance-18.6 ± 1.4 km.h-1) long-distance runners performed three exercise protocols: i) 10 km time trial, ii) incremental maximal exercise and iii) four constant load exercise related to sVT, sRCP and above that 72 hours apart. Results: Linear regression analysis revealed that sRCP was the best parameters to predict 10 km runner performance (R2=0.92; p<0.05). No differences was found between the intercept and slope of the relationship between sRCP and s10 km and the identity line (F=0.03; p>0.05) and during almost of entire race, the athletes choose a running speed not different from sRCP. During constant load protocol, all runners completed 10 km at sVT and sRCP, however 3 of 12 amateur and 9 of 19 elite athletes were able to complete 10 km above sRCP. All athletes who completed 10 km in the continuous loading protocols did not show significant changes in blood ph (p>0.05). However, it was not observed in the athletes who were unable to finish. Conclusion: In practice, this study showed sRCP as a useful and safe parameter to predict 10 km running performance and determine pacing strategies for runners, and that the blood buffering capacity is key to maintaining 10 km pacing strategy and performance.