When Vladimir Cerin was conditioning athletes--including tennis star Tracy Austin and pro basketball players Jamaal Wilkes and Kiki Vandeweghe--he wondered if he could apply his training ideas to racehorses.

The great horsemen, the Charlie Whittinghams and the Woody Stephenses, have all employed similar methods that are established as the profession's orthodoxy. But if the principles governing fitness for two-legged competitors could work for four-legged ones, Cerin thought he might revolutionize the thoroughbred sport. As he made a dramatic career change, Cerin recalled, "I thought I was going to set the world on fire." He has managed to establish himself on the tough California circuit; he ranks fifth in the trainer standings at Del Mar. But the scenario didn't develop in quite the way he had expected. Cerin's only previous exposure to horses had come when he was a child, growing up in the former Yugoslavia on a cooperative farm, where his father was in charge of thousands of horses, cattle and pigs. When he was 14 his family moved to Canada in search of a better life. Cerin got a soccer scholarship to UCLA, and studied kinesiology--the science of movement. As a graduate student his main focus was on physical conditioning for maximum performance.

When he started training, Cerin said, "All my athletes were taught to go as hard as they could for short bursts." He developed drills that would stress the body in the specific way that it would be taxed in competition. Vandeweghe wasn't quick enough, so Cerin put him through drills where he moved from point to point on a basketball court in 12-second bursts.

Cerin's regimen was grueling; Wilkes nicknamed him "Darth Vader" because he was so tough. But his athletes responded uncomplainingly. "These people are different from the rest of us," Cerin said. "They have a drive to succeed. Tracy Austin was as tough as anyone I've ever seen."

Ernie Vandeweghe, Kiki's father, said of Cerin, "We used to call him 'Mr. Speed.' He taught people to run faster. So I asked him: 'Do you think you could do this with a horse?' "

That planted the idea in Cerin's mind. Eventually he took a job as an assistant to trainer Rafael Martinez, worked for him for two years learning the basics, and in 1981 launched his own career. He was ready to apply to horses some of the techniques of conditioning human athletes--such as interval training.

A human runner might train by sprinting 200 meters, walking 200 meters till his pulse rate drops, then sprinting another 200 meters, walking, and so on. This is a well-established way to reach peak condition. So Cerin adapted the technique: He worked a horse a slow three-eighths of a mile, let him rest for five minutes, worked him again, rested him another five minutes and worked him again.

The results were unequivocal. "None of it worked," the trainer said. "If you did this for a week you'll have no horse left."

He soon understood the reason: "Horses' tendons and ligaments take about 48 hours to recover from exercise," Cerin said. "If you pound them twice a day, the materials will fatigue the way an airplane wing might fatigue--and break off."

He learned, too, that training an athlete harder and harder doesn't work for horses the way it does for people. Highly motivated athletes in peak condition are always striving to get fitter and fitter so they can improve their performance. But thoroughbreds are different. "Horses have tremendous aerobic capacity," Cerin said, "but once you reach a certain level they're not going to get any fitter. At that point you just keep them there and don't drive them into the ground. You don't have to make their exercise quite as severe the few days before a race; the term we use with humans is 'tapering.' Horses love to compete, but you have to keep them in a good mood."

Cerin watches the movement of his horses as carefully as he did his human trainees. (Kiki Vandeweghe once said that Cerin could tell what he had for breakfast by the way he moved in a drill.) With horses, the purpose of this scrutiny is to spot incipient physical problems. This, of course, is what all trainers do, and Cerin has come to manage his horses in a fairly orthodox fashion.

Cerin said the major differences between his methods and those of other trainers are in the area of nutrition. He believes that many horses suffer from acid in their stomachs and he commonly treats them with ulcer medication. To build their muscles he gives them creatine monohydrate--the same substance that many human athletes employ to increase their strength.

But for the most part Cerin operates the way trainers always have done: watching horses closely when they exercise, trying to keep them fit without working them too hard, keeping them mentally sharp and on edge for a race. After aspiring to revolutionize a tradition-bound profession, Cerin wound up reinventing the wheel.

"Charlie Whittingham had it right," he concluded. "What a surprise!"

Yesterday's horse racing

results, pages D16-17

CAPTION: Pros strive to get fitter, but horses are different, says Vladimir Cerin.