Secretariat didn’t just win races. He won them in a way that defied how racehorses are supposed to run. His defining characteristic was sustained acceleration: while nearly every other Thoroughbred in history slows down as a race progresses, Secretariat ran each successive quarter mile faster than the last. Combined with a physically extraordinary body, this produced performances so dominant that his records from 1973 still stand more than fifty years later.
The Reverse Speed Pattern
The single most remarkable thing about Secretariat was his acceleration pattern. In a typical horse race, Thoroughbreds run their fastest early and gradually tire. Even strong closers who make dramatic late moves are usually just passing horses that are slowing down more than they are. Secretariat did the opposite.
His 1973 Kentucky Derby is the clearest example. He ran the five quarter-mile segments in these times: 25.2 seconds, 24.0, 23.8, 23.4, and 23.0. Each quarter was faster than the one before it. He crossed the finish line in 1:59 2/5, the first horse ever to break two minutes in the Derby. That record still stands. No other horse matched even the two-minute barrier until Monarchos ran 1:59.97 in 2001.
This wasn’t a one-time anomaly. In the Preakness Stakes, he completed one quarter-mile split in under 22 seconds. In the Belmont Stakes, he and his only early challenger ran the opening half mile in 23 3/5 and 22 3/5 seconds, the fastest opening half in the race’s history. Where other horses would have collapsed from that pace, Secretariat kept building speed.
Margins of Victory That Defied Belief
Secretariat’s acceleration pattern meant that his leads grew enormous in the final stages of races. The Belmont Stakes is the defining image: he won by 31 lengths, a gap so vast that jockey Ron Turcotte looked back over his shoulder and couldn’t find another horse anywhere close. His time of 2:24 flat for the mile and a half remains the track record at Belmont Park, North America’s largest racetrack, and is widely considered the greatest single performance in Thoroughbred racing history.
When speed figure expert Andrew Beyer retroactively applied his modern methodology to that Belmont run, he calculated a figure of 139. For context, the best-rated horse in the decade prior to that analysis, Ghost Zapper, earned a 128. Secretariat’s number wasn’t just better. It was in a category by itself.
Record-Setting Across All Three Triple Crown Races
Secretariat set records in all three legs of the 1973 Triple Crown, something no horse before or since has done. His Kentucky Derby time of 1:59 2/5 was a track record. His Belmont time of 2:24 was a track record. And his Preakness time became the subject of a decades-long controversy that ultimately confirmed his dominance there too.
The electronic timer at Pimlico malfunctioned during the 1973 Preakness, recording a time of 1:55. Two independent clockers from the Daily Racing Form both hand-timed the race at 1:53 2/5, significantly faster. The official time was initially revised to 1:54 2/5 based on Pimlico’s own hand clocker, but in 2012 the Maryland Racing Commission reviewed the evidence using modern technology and unanimously changed the official time to 1:53, a stakes record.
Equally Dominant on Grass
Secretariat’s Triple Crown races were all run on dirt, but those who watched him train and race on turf believed he was even better on grass. During preparations for the Man o’ War Stakes, his exercise rider let him open up from the three-quarter pole, and Secretariat worked five-eighths of a mile in 57 seconds flat, a time that would be remarkable even for elite sprinters running a much shorter distance. Observers estimated he was 7 to 10 lengths superior on turf compared to his already historic dirt performances.
This versatility set him apart from many great racehorses, who tend to specialize on one surface. Secretariat moved over grass with a smoothness that people described as otherworldly, as though he barely touched the ground. In the Man o’ War Stakes itself, he appeared to toy with his competition.
A Heart More Than Twice the Normal Size
After Secretariat died in 1989, a necropsy revealed what many had suspected: his heart was enormous. The average Thoroughbred heart weighs about 8.5 to 9 pounds. Secretariat’s was estimated at 22 pounds, roughly two and a half times normal size. The veterinarian who examined it noted it was a third larger than any equine heart she had ever seen, and crucially, it was not diseased or abnormally shaped. All the chambers and valves were normal. It was simply a much bigger, more powerful pump.
A larger heart means more blood pumped per beat, which means more oxygen delivered to working muscles. This likely explains how Secretariat could sustain and even increase his speed deep into races when other horses were running out of oxygen and fading. Writer Marianna Haun developed a theory she called the “X Factor,” proposing that Secretariat inherited his oversized heart through an X chromosome from his dam, Somethingroyal, tracing back through the great broodmare sire Princequillo. The theory suggested this was why Secretariat’s daughters, who received his X chromosome, tended to produce better runners than his sons, who received his Y chromosome instead. However, subsequent mapping of the equine genome has shown that heart size is not actually carried on the X chromosome, even though it likely has a significant genetic component.
Why the Records Still Stand
More than fifty years of breeding advances, improved training methods, and better track surfaces have not produced a horse that can match what Secretariat did in 1973. His Kentucky Derby, Preakness, and Belmont times all remain records or near-records. His Beyer speed figure for the Belmont has never been approached. The combination of his reverse acceleration pattern, his physical gifts, and his ability to dominate on both dirt and turf made him not just a great racehorse but a statistical outlier that the sport has never replicated.
What fans and analysts keep returning to is not simply that he won, but how he won. A fast horse can set a record on a good day. Running each quarter mile faster than the last, pulling away from the field while still accelerating, suggests something fundamentally different about how his body processed effort. That acceleration pattern, powered by a heart that could flood his muscles with oxygen when every other horse was running on empty, is what made Secretariat’s performances unlike anything seen before or since.