A new study contends racehorses are gradually getting faster, despite views to the contrary held by the racing industry.
It also shows the greatest improvements in speeds have been over shorter distances.
Researchers from the University of Exeter went to great lengths to prove their point, looking at more than 616,000 race times run by almost 70,400 horses.
Dr Patrick Sharman and Dr Alastair Wilson examined data sets going back to the 1850s and also took into account the year of particular races, race speed and distance, how they were timed, how the official going was described and the age and sex of every horse involved, among other variables.
Elite-level animals
They looked at elite-level animals and also the racehorse population as a whole. Their results showed overall speeds are increasing, and the greatest increases in speed have been in the shorter distance races.
Recent data up to 2012 show improvements are continuing, largely driven by the speeds of sprinters particularly at elite level.
The slower rate of improvement in speeds over middle to long distances could mean horses are approaching a performance limit.
The authors point out this could also reflect a breeder preference for speed over endurance, they write in the Royal Society journal, Biology Letters.
There is a longstanding view that horse speeds have been plateauing, but this was not the case based on the study, said Dr Sharman from Exeter’s Penryn Campus in Cornwall.
“The challenge now is to find out whether this pattern of improvement has a genetic basis,” he said.
Improved training
The sustained improvements could also be down to improved training regimes, to jockey tactics or other environmental factors, he suggested.
"Previous studies have shown that the genetic contribution (heritability) to shorter distance races is higher than longer distance races, so it is very possible that genetic improvement could have impacted on race speeds as a result of the recent emphasis on shorter distance, faster races," said Dr Emmeline Hill, based at University College Dublin.
She is the scientist credited with discovering the “speed gene” in racehorses, and co-founded a company to commercialise the technology, Equinome.
“Targeted selection for racing performance traits using known genetic markers will continue to refine the thoroughbred as a population,” she said.
The improvements over time have not been continuous.
Speeds improved rapidly in the early 1900s and in the period from 1975 to the early 1990s.
This was put down to changes in riding style, but increased commercialisation of breeding may also have introduced genetic improvements.
