Kentucky Derby Times and Performance Limits

The graph above comes from a column I had at FiveThirtyEight one year ago. In it I looked at the data on winning times in the Kentucky Derby. Here is the interesting fact which prompted the column:

Since 1949, the time it takes thoroughbreds to run around the 1.25-mile track has averaged 2:02.25, and no winning race time has deviated by more than 3 seconds

Interestingly, horse speeds have plateaued but human speeds have not. Doping? Genetics? Sport science?

The 2014 race, run a few days after my column, played out true to form with California Chrome's winning with a time of 2:03.66.

Have a look at my column for a discussion.