The Impact of Horse Age on Speed and Performance

It’s long been understood that the age of a racehorse impacts their speed and performance.

Thoroughbreds begin racing at the age of two, before they’re finished developing. On the whole, two-year-olds are slower than three-year-olds, and three-year-olds are slower than horses aged four and five. Performance starts falling off again beyond the age of five.

The entire framework of racing is built around this understanding. Two-year-olds seldom compete outside of their own age group; when they do, they’re allowed to carry significantly less weight than their older rivals, to compensate for the fact they’re slower. When two-year-old The Platinum Queen defeated older rivals in the 2020 Prix de l’Abbaye de Longchamp (G1) in France, she carried only 116 pounds, 17 fewer than four-year-old runner-up White Lavender.

Three-year-olds are thoroughly capable of beating older horses during the second half of their sophomore season (perhaps with the benefit of a small weight break), but in general older horses will still hold an advantage. The Breeders’ Cup Classic (G1), the richest race in North American with a purse of $7 million, takes place in fall and is open to both three-year-olds and older horses. From 40 editions through 2023, three-year-olds have prevailed 13 times (32.5%), while horses aged four and five have combined to win 27 editions (67.5%).

Data reveals speed differences by age

With so many factors influencing the final times of races—the weather, the speed of the racing surface, the quality of the horses competing—you might assume it’s complicated to separate out the effects of age on speed and performance. Actually, it’s not that hard. All you need is a quality sampling of similar races for each age group.

That’s where Saratoga comes into play. The summer season at New York’s beloved track features several Grade 1 races held over seven furlongs on dirt, including the Hopeful for two-year-olds, the H. Allen Jerkens for three-year-olds, and the Forego for four-year-olds and upward.

By looking at the last 20 years of results, we can get a feel for the typical winning times produced by Grade 1 horses of different age groups when competing over the same track and same distance at roughly the same time of year. The 20-year sample size helps balance out differences in racetrack speed due to the races taking place over different days (though the Jerkens and the Forego have been held on the same afternoon almost every year since 2015).

The data paints a vivid picture:

During the 20 years from 2004 through 2023, the average winning time for the Hopeful was 1:23.34. During the same timeframe, the average winning time for the H. Allen Jerkens was 1:21.89, meaning the three-year-olds ran about 1.7% faster.

The older horses ran faster still. Over the course of 20 years, 14 four-year-olds, three five-year-olds, and three six-year-olds won the Forego in the average time of 1:21.67, 2.0% faster than the two-year-olds and about 0.3% faster than the three-year-olds.

Exceptions that prove the rule

The data gets really interesting when you dig into the exceptions: instances where younger horses ran faster than older horses.

For example, the single fastest time in our 60-horse sample belongs not to an older horse, but to three-year-old Runhappy, who won the 2015 H. Allen Jerkens (then the King’s Bishop) in 1:20.54, significantly faster than the 1:21.09 posted by Private Zone in the Forego on the same afternoon. It turns out Runhappy was well above average for his age; in the 2015 Breeders’ Cup Sprint, he defeated Private Zone by three-quarters of a length on his way to winning the Eclipse Award for champion male sprinter.

Now check out 2020, when two-year-old Jackie’s Warrior won the Hopeful in 1:21.29, far and away the fastest winning time in the last 20 years. It was also faster than the winning times from the Jerkens (1:22.53) and the Forego (1:21.71) that year. Jackie’s Warrior’s blazing clocking was a sign of good things to come: he would go on to win four additional Grade 1 races, including the 2021 Jerkens, and earn the title of 2021 champion male sprinter.

When a young horse defies the overall tendencies and runs meaningfully faster than older horses under similar conditions, they’re worth following as a potential champion in the making.

Projecting improvement with maturity

Speed and performance improvements tied to age can often be seen within a single horse. Consider two-time Horse of the Year California Chrome. During the first half of his two-year-old season, he earned Brisnet Speed ratings in the 74-78 range. During the second half, he improved to the 83-89 range and ended the year with a 101.

As a three-year-old, California Chrome won four Grade 1 races and posted triple-digit Brisnet Speed ratings in eight of his nine starts, peaking with a 110. Then, after an abbreviated four-year-old campaign, he returned at age five to post Brisnet Speed ratings as high as 112 and 115.

Projecting improvement with age can be useful when analyzing horses who are returning from layoffs. If a three-year-old was capable of running Brisnet Speed ratings in the 102-107 range, and now they’re returning from a winter break, it’s reasonable to assume they’ll be capable of posting faster numbers—perhaps 110 and higher—at age four.

Takeaways

Occasionally you’ll see a top-tier two-year-old who is fast enough to beat decent older horses, or an exceptional three-year-old who can conquer even the best older runners. But the average speed differences uncovered in our Saratoga analysis are substantial.

Look at it this way: there are 4,620 feet in seven furlongs, so if an average four-year-old runs 2% faster than an average two-year-old, that’s a difference of 92.4 feet, or around 10 lengths. Even average three-year-olds running 0.3% slower have a couple of lengths to make up against average older rivals.

These differences in lengths grow even larger over longer distances. The conclusion is unavoidable: on the whole, from age two through at least age five, racehorses improve in speed and performance as they mature.