Dosage and the Breeders' Cup

Dosage figures for Breeders' Cup race winners since the series was initiated in 1984 parallel the figures for the breed at large.  The relationship between Dosage figures and distance is graphically displayed in the following four charts.  The first two show the linear trend lines for DI and CD vs distance derived from all Breeders' Cup race winners since 1984.    

Chart 1.  DI vs Distance for Breeders' Cup Race Winners (1984-2009)

Chart 2.  CD vs Distance for Breeders' Cup Race Winners (1984-2009)

The next chart shows the trend line for the average CD of the Breeders' Cup race winners by year.  It indicates a slight decline in average CD over the lifetime of the Breeders' Cup.  Although it may not be immediately obvious as to why the average CD should drop, the explanation is apparent from the last chart which displays the annual average distance of Breeders' Cup races.  As the average distance has increased, we see the expected drop in CD consistent with an increase in stamina.  In fact, the two trend lines have an almost mirror image relationship

 Chart 3.  Avg CD of Breeders' Cup Race Winners by Year (1984-2009)

 Chart 4.  Avg Distance of Breeders' Cup Races by Year (1984-2009)