Like "Chariots of Fire," the admirable and inspirational British movie, which celebrated Olympic sprinting champions of the early '20s, the new American film, "Personal Best," is devoted to young athletes in training for the Olympics.

The setting and tone of "Personal Best," however, are contemporary rather than nostalgic--perhaps to a shocking fault in the minds of spectators reluctant to associate athletic dedication with sex, ribald humor, training violations and other loose, compromising aspects.

The fictional track stars celebrated by writer-director Robert Towne happen to be young women who fall in love, become estranged and eventually reconcile in friendship over an episodic four-year chronicle, beginning at the U.S. Olympic Trials in 1976 and concluding at the subsequent trials in 1980. It's possible the lesbian aspect will set off advance alarms that the movie as a whole tends to disarm. Ironically, "Personal Best" emerges as one of the few sexually provocative movies that also manages to keep sexuality in a sane perspective.

Towne is simply a tolerant and generous observer without an advocate's ax to grind or predilection to defend. He may also have a genius for using sexual intimacy as a pretext for comedy. This flair was apparent in "Chinatown" and "Shampoo," his most famous screenplays, and now that he's directing his own material, it may prove his most original and inventive stylistic tendency.

Towne's predilection is heterosexual to a voluptuously funny extent. Women fascinate him, and women athletes in particular knock him silly with awe and desire. "Personal Best" is amusing and endearing because it represents a genuine expression of fondness for girl jocks.

Although Towne himself is too preoccupied with the characters involved to generalize about the nature of their love affair, his lack of presumption is, in fact, a source of the film's appeal. Watching Mariel Hemingway as a teen-age track hopeful named Chris Cahill and Patrice Donnelly (a former hurdler who had never acted before) as Tory Skinner, the older, seasoned competitor who becomes her mentor and lover, you find the titillating aspects of their romance always being submerged in dramatic interest. Yes, you think, the affair starts as impulsively as it probably would in real life, and it falls apart under the pressure of competitive rivalry and shifting romantic susceptibilities in a way that looks equally plausible. Finally, it turns into something else--a friendship transcending the initial sexual attachment and subsequent disaffection--and the entire evolution makes emotional sense.

While irresistible and precious to both women, the love affair is also perceived as fleeting and inadequate to their needs. It's a passionate bond that begins in a kind of girlish narcissism and exploration, probably reinforced by the body-conscious and body-proud nature of these young women in particular. The bond weakens, however, as gawky, dependent Chris starts to mature and the protective Tory grows uneasy about a relationship that looks more sordid as she gets older and foresees her competitive career coming to an end. They've meant a lot to each other, but they reach a point where further meaning cannot be derived from a love affair.

Although Towne doesn't impose an interpretation, the pattern suggested by the romance of Chris and Tory couldn't appease homosexual advocates, because it implies that the homosexual attachment is transitory and subject to change. Neither character can be thought of as a confirmed lesbian. Chris drifts away from Tory in part because she forms an attachment to Kenny Moore, cast as a likably diffident swimmer named Denny.

There's a potentially worthy mate for Tory, a pretty superior specimen after all, in the delightfully cagey, sarcastic, frustrated character of the women's track coach, Terry Tingloff, played so smartly by Scott Glenn. It appears that they had been involved romantically in the past, and they're self-assertive equals in a way that's not only unusual but also sexually amusing and inspiring. However, Towne isn't concerned with fixing up Terry and Tory, and the question of her next attachment remains eternally open. He takes the heroines through the process of their relationship and feels no need to tidy up whatever futures await them.

Towne makes things easier on himself in certain respects by excluding huge and presumably relevant chunks of the life Chris and Tory lead together. For example, Chris' parents do a highly unlikely disappearing act after the opening sequence. Although the girls room together while on scholarship at Cal Poly in San Luis Obispo, there's no sense of their participation in a college environment beyond the gym or the track.

Towne may also be detected struggling to conceal certain limitations, notably Hemingway's obvious lack of foot speed, in the track sequences. Since Donnelly, a beautiful and subtly eloquent camera subject in motion or repose, and the other featured athletes--Jodi Anderson, Maren Seidler, Martha Watson, Emily Dole, Pam Spencer, Deby LaPlante, Jan Glotzer, Jane Frederick--are authentic track stars (Hemingway looks more athletic swimming than running or jumping), a minimum of fudging is necessary.

Towne goes overboard demonstrating a pictorial flair in "Personal Best," in which the training and competition sequences are so lavish that they are almost bombastic. The freshest pictorial scherzos in "Personal Best" turn out to be funny interludes, like the playful sequence of crotch shots which linger on women high jumpers vaulting backward over the bar or the sequence which ends with Moore hitting the end of the pool headfirst after sneaking underwater looks at Hemingway as they do laps.

Track fans ought to find the athletic milieu unusually vivid and authentic. Towne put himself in an early financial hole by shooting about 20 movies' worth of background footage at the 1980 trials in Eugene, Ore., using some of it at both ends of his picture. In fact, it's possible that the movie is stocked with more training and competition footage than nonfans will be prepared to savor. Incidentally, Jane Frederick, who plays the track star named Fern Wadkins, was indispensable to the creation and evolution of "Personal Best." Towne encountered her out-lifting him with ease in the UCLA weight room, a scene reproduced in the movie by Hemingway and Moore. She went on to introduce him to other superwomen.

Obviously, the story can't have an Olympic Games payoff, since the athletes are pointing toward 1980. Towne never had such a payoff in mind. As the title suggests, he was interested in forms of competitive effort and self-realization that are more personal than public. "Personal Best" is an encouraging first feature, the work of an intensely personal Hollywood filmmaker determined to give his best to the medium.