The Secret of Fast Horses

The secret behind the fastest thoroughbreds doesn't make a lot of horse sense. A great racehorse is more than just quick footed -- it must also be rather average.

"A horse's leg resembles a pogo stick that uses energy stored in the muscles and tendons to propel the animal forwards and upwards," says Alan Wilson of the Royal Veterinary College in the UK. "Fast horses can bring their legs forward quickly in preparation for the next stride but that this is more difficult and therefore slower for large and long-legged horses."

Some 80 percent of modern thoroughbred racehorses have in their pedigree the undefeated 18th Century horse Eclipse, Wilson's team says. Yet scientists haven't been able to figure out what makes some horses faster than others.

Wilson led new research that modeled the legs of Eclipse and other horses on a computer. The work combined what was known about Eclipse with data on the shape and structure of modern horses to develop mathematical and computer models of their movement.

Eclipse generated a lot of horsepower because of its "averageness," the study concluded.

"Analysis shows that Eclipse's body shape and everything about him seems to have been right in the middle of the normal range, suggesting that all the factors for speed were perfectly matched."

The ongoing research examines how other animals and humans move and could inform the design of more stable robots, the scientists say. It might even help them get a better handle on how dinosaurs ambled about.