Tracy Austin was a stranger to pathos. She was healthy, wealthy, and sheltered from the harsher struggles that take place off the tennis court.

"Before, everything came so fast," she said. "I was always going up, up, up. It's not so fast anymore. I guess you have to slow down at some point."

This year, her body did. A body is a given, although as Austin learned, an inconstant one. The back problem (a vertebra slips out of alignment and pushes on the sciatic nerve) that forced her to miss 4 1/2 months in 1981 flared again in January. A month later, a waiter spilled scalding water on her back and shoulder. Last Thursday, she developed tendinitis in her right shoulder. "I got burned, my back was bad, I had the stomach flu twice," she said. "It certainly caught up to me all in one year."

Austin, who won the U.S. Open a year ago, has played in only seven tournaments in 1982 (defaulting once, retiring once). She lost to Billie Jean King in the quarterfinals at Wimbledon, Hana Mandlikova in the quarterfinals of the French Open and won the Wells Fargo Open in San Diego in August.

At 19, she is a new woman, a changed woman. Growing up is not a revolutionary act. Some of the changes would have come naturally. But the struggle of this year, the knowledge that life is not something worn on a charm bracelet, has contributed to the change. "How did it change me? It's tough to say," she said. "I don't know if it made me grow up or if I was just growing up anyway. It made me stronger. It made me realize how lucky I was to have the life style I do."

She says she does not want this to sound like a tragedy. But, her voice warbles just a bit when she says, "There were real tough days in the last year, too many, too many."

Every time she thought she was getting better, Austin said, "something else happened." Trying to "get back where I was too fast" made things worse.

"I think she's scared," said Pam Shriver.

Andrea Jaeger, who has had her share of injuries (she and Austin compare notes and sympathize), remembers being shocked when Austin told her once last year she was practicing only six minutes a day. "It's got to be really hard," Jaeger said.

Publicly, Austin seems softer. "More vulnerable," she said. When Catherine Tanvier sprained her right ankle during their first-round match and had to default, Austin virtually ran to the other side of the court to offer sympathy "because of what I've been through." Of course, she said, "when I got there, I didn't know what to do."

Chris Evert Lloyd, who has been through so many of the same things Austin has, though not a prolonged period of injury, said, "I think it makes you grow up a little bit. In Tracy's case, I think she's been forced to find other things than tennis to rely on, to feel secure about. She used to be a little more nervous, a little more uptight. She's calmer, nicer now."

Austin said those things haven't changed. "I think I always have been sensitive, real emotional . . . I didn't want to show it. I was young, a bit shy. I think I'm just more open now."

A willingness to share those parts of herself with the public is a change in itself. If she is more open with the press, she is also more introspective. "I don't know if it's the injuries or what," she said. "It's just made me realize there are other things. It put everything in perspective."

Her coach, Marty Riessen, said, "If she had been healthy and playing, there probably wouldn't have been as big a change. She's done a lot of things. She's had time to reflect. It's made an impact."

Before, life was simple: she practiced, she studied, she won. "Nothing seemed to go wrong," said her mother, Jeanne. "She said, 'Isn't this the way the world is supposed to be?' Now, it's 'Oh, there can be problems.' If you try, and succeed, you don't realize that a lot of people try, and don't succeed. You're not being peculiar. You just don't know.

"She's more appreciative of things and people and success and what people do for her."

There are other changes, too.

"I think she has learned there are other things than tennis," Evert said, winking.

"Boys," said her mother.

Matt Anger is his name. To see Austin sitting hand in hand with him in the players' lounge before a match is to know that tennis is no longer the only love of her life. "There is a time and a place for everything," she said. "When I was growing up, at age 12 or 14, I didn't want a boyfriend. I didn't care. So I was interested in tennis. I don't want to make it sound bad that I was single-minded about tennis and school."

When she became the youngest person ever to win the Open (16), "Tennis was totally her life," Riessen said. "Now, she looks at other things and wonders whether she would like to do them. She understands there is a lot more out there. Another type of job, maybe."

The thing that was always so striking about Austin was the contrast between the little girl who wore pinafores with hearts on them, and her strong will. She was so purposeful so young. So much of her game is steely mental toughness.

To win, Austin said she does not need to be single-minded about life: "When I'm content, I concentrate better."

Besides, she says, she is still single-minded when she is on the tennis court, as Riessen said she must be.

"Right now, she's an unknown quantity because she hasn't played . . . I don't think she knows right at the moment (if she has the single-mindedness) because of the injuries," Riessen said. "We know sometime it's going to be fine but we don't know about these two weeks. It is a discipline. You just don't turn it on and off. It's something you develop and fine-tune."

Others wonder whether Austin may be experiencing a period of adjustment simply because tennis isn't the only thing in her life anymore. "Chris at 18 had a bad year," Riessen said. "Martina won two Wimbledons and then other things popped up and now she's back on track. Not many can just continue it . . . They all go through it."

And that, he said, leads to inevitable questions about how long to play. "I think Chris is looking for the moment when to stop," Riessen said. "I don't think Tracy is looking for it. But you ask those questions. You have to wonder, 'If I can't play tennis what am I going to do?' "

This may have been the most healthy part of Austin's year. "I've tried," she said. "What else can I do? I came back and played the French. I went to Birmingham and got sick. I played Wimbledon. I went to Canada and got sick again. I've tried.

"When people say I don't care, I wouldn't have gotten tendinitis if I didn't care. I wouldn't have practiced so hard. I love tennis. I love many things. I think you can have the best of both worlds."

Next year she plans to play a normal schedule.