Teams of the American League West, consider yourselves warned: George Brett no longer is too big for his britches.

"I came to spring training with a 32 waist," said Brett, still the yardstick by which any Kansas City Royals' season is measured."I went in a store, got some Ralph Lauren jeans, size 32. Tried them on. And they fit! I couldn't believe it. Normally, I'm a 34-inch waist with 35 legs and a 32 butt." Brett, almost 35, is noticeably trimmer. He looks healthier, even younger. All winter, he worked out, eventually running in a 10-kilometer race in Redondo Beach, Calif., on Super Bowl Sunday. (He finished in 52 minutes but said he would have done better if brother Ken hadn't held him back).

It was all part of a fitness program that Brett and the Royals hope will make for a productive, perhaps terrific, season. It grew out of a suspicion that things might have gone differently in 1987 had Brett arrived in shape and stayed healthy. A veteran of 14 seasons and at least that many injuries, Brett missed 44 games with two ailments, batted .290 and batted in 78 runs. The Royals finished two games behind the Minnesota Twins in the division race.

"Had he played in 150 games, I think you might have seen a different ending last year," said Royals manager John Wathan.

Clearly, there is a relationship between Brett's health and the Royals' success. When Brett plays, the Royals, more often than not, win. Only once since 1979 has he played as many as 150 games; that year, 1985, Brett had a monstrous season (.335, 30 home runs, 112 RBI) and Kansas City won the World Series.

Not coincidentally, that was the last time Brett made an offseason commitment similar to this one.

"At the time, I was the heaviest I'd ever been. I was 218. My clothes didn't fit and I looked at myself in the mirror and just saw this bloated body.

"That's when I decided I was going to cut out all the bad things for my body. I went six weeks with no beer. No alcohol at all. No red meat."

Brett shed 30 pounds that winter and probably had his best season. He won a Gold Glove at third base, led the league in slugging, finished second in batting, total bases, on-base percentage and extra-base hits and came within two intentional walks of tying Ted Williams' record (33). He batted .348 in the playoffs, .370 in the Series. But most important, he played 155 games.

That's the stat that pushed him through the workouts this time.

"I'd never worked out until '84. I always felt too good. But I'm going to be 35 in a month and a half and I've played 13 years on Astroturf," said Brett. "All of a sudden, I had a bad year, signed a big contract, started getting hurt. The Royals told me, `Maybe if you were in better shape, you wouldn't get hurt.'

"So I started working out. I ran, I dieted, I played racquetball, I played tennis, I swam, I rode my bike, I did everything. I found something to do for two hours every day."

Brett is driven by a sense of history, too. His place in the game, a spot in Cooperstown, could hinge on the next two or three seasons and Brett knows it.

For example, he wonders about his chances of getting 3,000 hits. He has averaged 142 the past six seasons. With his lifetime average of .312, he would get 187 hits a year if he batted 600 times.

The way Brett sees it, injuries have cost him about 45 hits a year. Over a career, that's enough to separate the great from the very good.

Brett never has found much joy in merely being very good.

"Hitting .290 for the last two years, that's good for a lot of people but not George Brett," Wathan said. "That's why he's worked very hard to get healthy again."

Brett makes Jack Clark or Paul Molitor look like Lou Gehrig. From elbow strains to shoulder sprains, from hamstrings to hemorrhoids, the former third baseman he moved to first last year in part to shield him from risk figures he has spent too much time with doctors. He has missed three All-Star Games with injury.

Last year was the worst. There were just three games between the 20 he missed with pulled rib muscles and the 24 he lost to a torn knee ligament. Brett failed to hit .300 for the second straight year and against the Twins, the Royals' most important opponent, Brett managed just four hits and six RBI in 29 at-bats (.138).

Brett was like a caged animal. He couldn't stand to be away from the team, couldn't stand to be around it.

"George can be a bear," Wathan said. "I've never seen a more fierce competitor. So he didn't know what to do when he wasn't playing. The guys didn't even want him around. It was like `Get him outta here."'

Brett is excited about this season, he's enjoying the challenge of first base, he's encouraged by a promise from Wathan to play a more aggressive, offensive style and he likes the Royals' chances of unseating the Twins.

"I'm gonna try to play as many games as I possibly can," Brett said. "If I play 155 games, I think I can have a very similar season to what I had in 1985. I play 130, I could go out and hit .290 again. It's no fun hitting under .300."