Racehorse Top Speed – Faster Than You Think!

Horses run much faster than humans, even an old one can outrun you, but one type of horse can gallop quicker than any other, so what is the racehorse top speed? The majority of racehorses are Thoroughbreds, but Quarter Horse racing is also quite common. Here we will explore just how fast these magnificent horses can go.

Racehorse Top Speed

The average speed of a galloping horse is 30 miles per hour. But the top speed of a racehorse is much higher. The fastest speed ever recorded by a racehorse is 43.97 miles per hour.

This record, confirmed by the Guinness Book of World Records goes to Winning Brew. A just two years old, Winning Brew, ran at the Penn National Race Course in 2008 setting this impressive speed. She did not go on to have an illustrious racing career, like other legendary horses.

Winning Brew’s record is significantly faster than the average speed of the Kentucky Derby winner. The average Kentucky Derby wins with a speed of 37 miles per hour. Even the great Secretariat never broke the 40 miles per hour mark, winning the Kentucky Derby with a speed of 38 miles per hour.

Racehorse Top Speed

American Quarter Horse

Another type of racehorse is the Quarter Horse. This breed has an excellent ability to accelerate quickly. They race over a distance of a quarter of a mile, whereas Thoroughbreds usually race longer distances.

Over this shorter distance, the Quarter Horse top speed is faster than a Thoroughbred. The fastest ever speeds clocked by a Quarter Horse is 55 miles per hour, faster than the speed limit on many roads!

What Determines Racehorse Speed

Several factors influence the horses’ top speed. The confirmation of the horse, its muscle formation, and stride length have the biggest impact. The height of the horse does not always translate into a faster horse.

Research into the great racehorse Eclipse found that he was average in all aspects. He was not too tall or short, or big-bodied. One thing they did conclude is that Eclipse was a very balanced horse.

The Horse Conformation Handbook

To see some proof that height is not very important, just look at the racing legend Seabiscuit. Seabiscuit took the racing world by storm, winning several races, including a match race against the 1937 Kentucky Derby winner, War Admiral. This mighty little horse stood at only 15 hands tall.


The X-Factor when talking about racehorses, is not about their star power, though these horses have that too, it is all about the heart. The theory about horses with a larger heart accomplishing more on the racetrack dates to 1789 when Eclipse died.

During the postmortem, the surgeon discovered that Eclipse’s heart was twice the size of the average horse. The average horse’s heart weighs 7 pounds, while Eclipse’s weighed 14 pounds.

Several decades later, in 1989, when one of the greatest racehorses of all time, Secretariat, died, the autopsy left the surgeons stunned. Dr. Thomas Swerczek, a pathologist at the University of Kentucky, said at the time “We just stood there in stunned silence,” “There were no problems with it. It was just this huge engine.” The estimated weight of the Secretariat’s heart is 22 pounds.

The doctor, says it is this heart that explains how Secretariat won the Belmont by such an incredible lead. The Australian champion racehorse Phar Lap, also had a heart two times as big as the average at 14 pounds.

But it was Secretariat’s heart size that led to research into the X-Factor. The research found that this heart size is genetic and passes from the mother to her foal. Only the X chromosome can pass this gene on.


After this discovery researchers traced family lines all the way back to the 1800s. All the lines go to one mare, Pocahontas, an English Thoroughbred. Pocahontas lived in England in 1837 and is a descendant of Eclipse. Both Secretariat and Phar Lap descend from Eclipse.

Spillett is the dam of Eclipse and is responsible for giving him the big heart gene. This theory explains why Secretariat did not produce the same results as a stud, but what he did do was produce fantastic daughters who went on to breed winners.

Pocahontas Thoroughbred

This large heart gave these horses an advantage on the racetrack. It allows the horse’s body to pump more oxygen, giving it more stamina and speed. The X-Factor is found in many of history’s greatest racehorses, including, War Admiral, Man O’War, Seattle Slew, Northern Dancer, and Citation.

Researchers are still trying to unlock the genetic marker for the X-Factor.

Fastest Race Horse Conclusion

As you can see the racehorse top speed is impressive, even without the X-Factor. The X-Factor is a fascinating subject that explains those horses in history that reach legendary status. Do You have a favorite racehorse from history? 

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