Because thoroughbred race horses are thoroughly bred, you might think that they would be getting faster at least as fast as human runners have been.
But that hasn’t been obvious.
For example, all three of Secretariat’s 1973 records in the American Triple Crown races for 3-year-olds still stand. (Originally, Secretariat was not credited with the Preakness record but a review of the videotape in 2012 showed that the original timing was faulty).
In contrast, in men’s track, the oldest current record is Kevin Young’s 400 m hurdle time at the 1992 Olympics. In women’s track, quite a few records go back to the 1980s before stronger drug testing was imposed after the 1988 Olympics, but no women’s running records are as old as Secretariat’s marks.
It’s been widely stated that thoroughbreds aren’t getting faster.
In the English-speaking world, thoroughbreds have been bred relatively methodically for several centuries. Shakespeare, for example, used the word “race” to mean both a breed (e.g., “a noble race of kings”) and a competition of running speed. The obvious overlap was the nationwide goal of developing a race of racehorses.
So it is possible that most of the potential has been wrung out of them already.
However, a 2015 study of British racehorses from 1850 onward came to the conclusion that there has been a post-Secretariat surge in speed, especially at shorter distances:
Racehorses are getting faster
Patrick Sharman, Alastair J. Wilson
Published 24 June 2015 .DOI: 10.1098/rsbl.2015.0310
Previous studies have concluded that thoroughbred racehorse speed is improving very slowly, if at all, despite heritable variation for performance and putatively intensive selective breeding. This has led to the suggestion that racehorses have reached a selection limit. However, previous studies have been limited, focusing only on the winning times of a few elite races run over middle and long distances, and failing to account for potentially confounding factors. Using a much larger dataset covering the full range of race distances and accounting for variation in factors such as ground softness, we show that improvement is, in fact, ongoing for the population as a whole, but driven largely by increasing speed in sprint races. In contrast, speed over middle and long distances, at least at the elite level, appears to be reaching an asymptote. Whether this reflects a selection limit to speed over middle and long distances or a shift in breeding practices to target sprint performances remains to be determined.
They found a plateau from 1910 into the 1970s, but a resurgence of improvement in recent decades.
Here’s a graph showing that records have been following recently for very short distances, but less so for long distances:
The records for the short distances have largely been set in the 21st century, which is less true for longer distances.
One possible reason for the enhancement in sprinting over endurance since the 1970s is the huge genealogical influence of Northern Dancer, winner of 1964 Kentucky Derby and Preakness (but not the longer Belmont). He set the Kentucky Derby mark that Secretariat broke, and Northern Dancer’s 2:00.0 flat has only been bested once since Secretariat, by Monarchos in 2001. Northern Dancer was a small, fast horse who retired to become the leading sire of the past 60 years.
When Roger Bannister broke the 4 minute mile in 1954, after a long stretch from 1945 without a new world record, it led to a rapid burst of better times. In the Kentucky Derby, Northern Dancer reached the 2 minute barrier in 1964 and Secretariat broke it in 1973, but then nothing much happened.
How much is record breaking in human running a social construct? Running is a fairly marginal sport. In between Olympics, the main way to get your name on the TV sports report is to break a world record. For example, Sir Dr. Roger Bannister, who is now 88, has enjoyed a more kick-ass life for what he did back in May 1954 than if he’s run 4:00.1. (A guy I knew in the marketing research business was at the Oxford track that day as a 12 year old spectator and could recount P.A. announcer Norris “Guinness Book of World Records” McWhirter’s famous announcement: “… in a time which, subject to ratification, is a track record, an English native record, a United Kingdom record, a European record, in a time of three minutes…”)
Jockeys, on the other hand, are seldom incentivized to care about breaking records. Horses don’t care about breaking records. They do, however, appear to care about beating the other horses.
That raises the question of whether Secretariat, who, in the most famous moment in American racing history, won the Belmont by 31 lengths (I was playing in a baseball game that ground to a halt while everybody listened to the race on the radio) and setting a record of 2:24 , cared about running fast for the sake of running fast.