We recently published a study titled “Physiological Parameters Associated with 24 Hour Run Performance.” The paper is open access if anyone wants to read it. Just type the title into scholar.googel.com. One of the interesting things we observed in the data is that average running speed was highly correlated with fitness, but total mileage completed during the race was not. Taken in context with studies done by Guillaume Y Millet, it seems that if all other variables are held equal, the person that has the most cardio respiratory fitness will likely have the best performance in a race. Unfortunately, this is rarely the case except in a laboratory setting. In an actual race, several variables seem to act to limit or halt performance early. These variables likely include: Nutrition, susceptibility to injury, and psychological arousal. If for instance, you fail to take in enough salt, you could develop hyponatremia (too little sodium in your blood), which could end your race early. Or, if your leg joints were more unstable, you could develop a race ending injury. The thing which is interesting to me is about our study is the possibility that given enough data, we could predict an optimum race pace. I will attempt in the near future to publish our regression equation for anyone interested. It should be noted that this was developed for a hot, summer race, and the ideal pace may differ depending on environmental conditions. The idea of this is somewhat supported in the literature by the works of Martin D. Hoffman who has previously shown that minimizing changes in pace throughout a race is a strategy often associated with winning.