From the cradle to the grave: how fast can we run?

I model average running speed on distances from 5000 m to the marathon as a function of age, distance and sex. Using data on US age-dependent road-racing records, I simulate optimal performance for ages ranging from 3 to 95 years. The results of the correlation between running speed and age are in line with medical results on the relation between age and maximal oxygen uptake. The results show that official track and field age-grading overestimates human performance at older ages.