Running in one of the Triple Crown races takes a special kind of athlete, and thoroughbred horses are arguably the best the world has to offer.

Trained and conditioned since their second birthday, these bright animals study to become runners, ball players, jumpers, and dancers.

But of the 35,000 three-year-old thoroughbred horses in the world today, only 20 of the best-conditioned sprinters will line up in the starting gate at Churchill Downs for the
running of the Kentucky Derby.

Each year more than 400 horses are nominated by their owners for the Derby, yet only the 20 horses that have won the most money in the winter's biggest races will earn the right to run.

And running is these horses' specialty. Widely believed to be faster than cheetahs in endurance races, the thoroughbred is the fastest breed of horse in the world, and can
maintain a speed of 45 miles (72 km) per hour for a distance of more than a mile (1.6 km), making the Derby's 1¼ mile-long race the fastest two minutes in sports.

What's all that stuff the horse is wearing?

Just as fans wouldn't show up underdressed for the glamour of a Triple Crown event, the horses will show up looking their best too, with one exception. What they're wearing that day has weight restrictions. Colts and geldings can't carry more than 126 pounds, and fillies can't carry more than 121 pounds.

Obviously owners want their horses carrying very little weight. But a good deal of that weight is the jockey, who rarely weighs more than 115 pounds and can't be spared.
Each horse must be weighed out before they are paraded to the starting gate where each horse gets its own stall.

Thoroughbred horses typically stand 16 hands tall from hoof to withers, the highest point on the horse's back. A hand equals four inches (10 cm), the average width of a
man's hand.

From head to hoof, the horse will be dressed to win. A bridle made of leather straps is fitted onto its head to hold the bit and reins in place. And blinkers, which are
cup-shaped devices placed next to the eyes, will keep the horse from seeing anything but what's directly in front of him or her.

The jockey sits on a small leather patch on top of a number cloth, which serves as a saddle. A leather or nylon strap, called a girth, stretches around the horse's belly to
keep it in place. And tiny, three-ounce aluminum shoes (called plates) will be the 1,000 pounds of galloping horse's last line of support during the two-minute race.

And they're off!

By the time the starter sounds the bell that opens the starting gate, the horses are raring to go. A fast start through the crowd is crucial in the first quarter-mile. But not too fast. In 1986 Top Avenger zoomed out of the gate and ripped through the first quarter-mile in 21 4/5 seconds (race times are measured in fifths of a second, not hundredths), setting a Kentucky Derby record. But Avenger couldn't keep up the pace and finished 19th.

The typical thoroughbred horse is capable of running only a quarter of a mile (400 meters) or so at its peak speed, so much of the strategy of racing is determining the best moment at which to start the burst.

By comparison, a human sprinter, who can reach top speeds of 25 mph, tends to lose speed after just 65 meters and would offer no challenge at all.

Once the field of competitors reaches the backstretch, all the horses start taking aim at Secretariat's record time of 1:59 2/5 in 1973. Although many have tried, only one
other horse has finished the Derby in less than two minutes (Monarchos, 2001).

And in the final stretch the horses jockey for position and make their furious dash for the finish line. In 127 races, only 21 horses have ever led from start to finish, so expect some excitement in the last quarter-mile.

And remember that in the end it's not the jockey, owner or trainer that is the difference between winning and losing . . . it's usually the horse's nose.