In recent years, much has been written and said about the alleged declining durability of North American racehorses and how Thoroughbreds have increasingly been bred for speed at the expense of stamina.  As one indicator of the American Thoroughbred’s ability to carry speed over 1 ¼ miles, I looked at data from the Kentucky Derby to see how the winners’ times have trended since the Derby distance was changed in 1896 from 1 ½ miles to 1 ¼ miles.  Following is a summary of my calculations condensed mostly into ten-year components.

Average winning time for:

2010-2019.  2:03.92
2001-2009.  2:01.99
1990-2000.  2:02.27
1980-1989.  2:02.46
1970-1979.  2:01.78
1960-1969.  2:01.68
1950-1959.  2:02.54
1940-1949.  2:04.90
1930-1939.  2:04.54
1920-1929.  2:06.70
1910-1919.  2:06.36
1900-1909.  2:09.58
1896-1899.  2:07.81

(From 2001 to the present the Derby was clocked in tenths of seconds. From 1906 through 2000 it was clocked in one-fifth seconds. From 1896 through 1905 the race was clocked in one-fourth seconds.)

As speed figures demonstrate, such factors as track condition and weather affect performance on any given day.  With this in mind, it is still revealing to look at the twists and turns of Kentucky Derby winning times since 1896.  From 1896 through the 1930s, winning times markedly improved…and leveled off in the 1940s. Subsequently, average winning times decreased in the 1950s through the decade of the 1960s and stabilized in the 1970s.  Since then, average winning times have increased slightly. 

It could be that the American Thoroughbred reached its genetic speed ceiling for a 1 ¼ classic race fifty to sixty years ago and the breed has regressed somewhat since…or at least not improved. While no hard conclusions can be drawn with a data set from one classic race, it is plausible that North American foal crops of recent decades are not as suited genetically for the 10-furlong distance as their predecessors from the ’60s, and ’70s.  Another hypothesis is that trainers in the modern era are not as skilled as their forerunners in preparing racehorses for classic distances. These explanations are, of course, not mutually exclusive and both likely contain an element of truth. 

Copyright © 2020 Horse Racing Business