Frankie's Interviewed on NPR's All Things Considered

The study found that jockeys have adjusted their riding styles to minimize so-called inertial losses — the energy horses spend bouncing their riders up and down and forward and backward with each stride.

By placing motion sensors on jockeys and their mounts, a team from the Structure and Motion Laboratory at the Royal Veterinary College in the United Kingdom showed that modern jockeys remain steady, even though their horses are bobbing up and down and rocking back and forth with each stride.

"The jockey's a bit like a person skiing down a mogul field," says Alan Wilson, a professor in locomotor biomechanics at the Royal Veterinary College. "Their feet are going up and down, but their body is following a smooth path."

The result is that it's easier for a racehorse to carry a jockey than a sandbag of equal weight that's attached to the saddle, Wilson says.

The discovery emerged from research by Wilson and his team to figure out how much extra effort it takes for a racehorse to carry a jockey.

The team studied racing history and realized that jockeys in the U.K. radically changed their riding posture in the early 1900s. Instead of sitting upright in the saddle, they began to crouch and put their weight on the stirrups.

It turned out the new style had been developed by an American jockey named Tod Sloan.

"This guy Sloan moved to the U.K. in 1897 and started riding horses in that way here," Wilson says. As other jockeys copied the technique over the next decade, he says, winning race times decreased by more than 5 percent.

And ever since then, jockeys have been refining the crouch posture, says Frank Lovato Jr., 46, a U.S. jockey who rode in more than 15,000 races before retiring a few years ago.

"In the 1930s and 1940s, jockeys rode with shorter and shorter stirrups and found that it was a more effective way to make a horse run faster," Lovato says.

And these days, he says, they study high-definition video of races to improve their technique.

"While the horse is running underneath you, you're basically trying to be weightless on top of their back," Lovato says.

That has made horse racing a lot more demanding for jockeys, whose legs and arms work like pistons for the entire race. Studies show a jockey's heart rate can hit 180 beats per minute.

So jockeys spend a lot more time on physical training than they used to, Lovato says.

Many do that using something Lovato invented when he was recovering from a racing injury. It's an artificial horse called the Equicizer that uses springs to simulate the motion of a horse.

Lovato, who lives in Norwalk, Ohio, these days, says training on devices like the Equicizer enable jockeys to maintain their form for an entire race.

"Twenty years ago, you'd see a lot more riders with their butts bouncing off the saddle" late in a race, Lovato says. "Nowadays, riders are holding their posture a lot longer."