Motorcycle maintenance has its zen, skiing its "inner" view, running its euphoria. And bowling? Just walking into a bowling center (they don't call them alleys, please) is like stepping back into the womb. It's cozy, it's dark, it's primeval.

The noise inside is as regular as a heartbeat. The whole cavernous building seems to breathe on its own. The bowling ball rumbles down the lane and thwaps against the pins. In reflex action, the automatic pin-setter descends to pick up and arrange. Multiply this by 40 lanes or so, and the effect is hypnotic.

But whatever its psychic appeal, it's becoming a national pastime: the National Bowling Council counts 64 million active bowlers.

On a league night, not everyone at River Bowl in Bethesda is in a bowling league. The really serious players wear monogrammed bowling shirts in purple polyester with team names on the back -- names like the Erratic 5, Disco Ducks, Woodpeckers. Their eyes are on the pins, or on the scoresheet projected on a screen overhead. Since it's impossible to resist turning on the light at the scoring console just once, the nonleague bowlers are easily identified on their arrival: they're the ones sitting under the bunny hand-shadow patterns.

There's all kinds of people: dudes who've never picked up a bowling ball in their lives stalk from one end of the room to the other, a young couple's two-year-old cradles his chin in an empty ball slot in the ball rack.

One wiry guy in his early 40s smoothly rolls a 16-pounder down the lane. Steve Zetti, he says his name is, but the name on the scoresheet is Chip. "Chip --" he explains, "the name I bowl by." He's muscular but a little pale, a person who only gets exercise indoors. For him, it all started in 1962, when he bowled as a sub for a government league. "Right now I'm bowling four nights a week," and he names the leagues and nights. "Then some nights I sub. Other than that, I stay home."

He and his wife Frances are trying something new -- they're in a league together. She allows as how she's a bowling widow and this is "a night out for us together." He allows as how "If she would let me, I'd bowl every night of the week."

During the week these league bowlers are older, family types. Then on Saturday night, it's couples on dates. "You couldn't talk them into joining leagues," says one former manager of a bowling center.

But maybe later. Both in their early 20s, Ron Parry taught his friend Louise Martinez to bowl on their first date. "Bowling is an unimposing, non-threatening thing to do on a first date. You can't be scared of a guy who takes you to a bowling alley," says Parry. "It beats asking her to go out and get a few drinks." A year and a half later, they're both in leagues, and he's bought her her own bowling ball, etched with the nickname, "Spunky."

There are other draws to the sport: "I don't like to be outside in the cold weather," says Martinez.

Some bowlers take it all very seriously. One of these is Terri Steiner of Bethesda, who, with friends Marcia Hanin and Sandi Ehrlich, holds first place in a 26-team league called the Potomac Posies. Steiner and Hanin have come out on a rainy Sunday night to practice up. ("Don't look at the scores. We did so bad.") They're both 27 but look 17 in their tight jeans. "We didn't have a good night tonight," Steiner says. "There are some very annoying people next to us. They keep coming on our side. That guy gets ready to bowl, he drops the ball on our side."

Actually, Steiner belongs to two leagues. "The Chevy Chasers play on Mondays. They all drive up in their station wagons.On Tuesdays, when the Potomac Posies play, I am embarrassed in my Grand Prix. Everyone has a Cadillac or Lincoln Continental, and it's a real fashion show." So much for the myth of women-in-rollers hanging around bowling alleys.

Steiner has really had it with the six teenagers in the next lane: "Now Marcia, why do these kids come bowling? They don't know what they're doing. They're not interested in the sport. They're just interested in smoking 97 cigarettes a night."

"I like the challenge," says Steiner. "I like all games. I like to make a small wager on any game I play." Tonight, loser paid, and Hanin good-naturedly picked up the scoresheet.

Another common wager works this way. If you've got five people bowling against each other, they each throw in five bucks before the games begin, and the person with the high average for the night ends up with $25.

What keeps them bowling? "People bowl for the same reason they do anything that's goal-oriented," says Les Goldberg, president of Bowl America, which runs 18 centers in the Washington area. "People like to succeed at things. In bowling, almost everybody can find something to feel good about. 'I did this. I accomplished something.'

"There are fewer and fewer chances to have little successes. I want to make a decision; the computer says no. But we can go out and throw a strike and we feel good about ourselves."

"Bowlers, by and large, are the most competitive sports-minded people there are," says Matt Bennie, who's secretary of the Nation's Capital Area Bowling Association. He started bowling at age 16, when he was a pin-boy, in the days before automation, and today he's 72 and still bowling. "I bowl for relaxation, for sport, because I like the game, and it's exercise. Foremost over everything it's exercise."

It's a sanctioned opportunity, like many sports, to throw things and to act out aggressions. "I recall very clearly," says Bennie, "when I was in the military service back in 1923, we used to delight in going down to the bowling lanes and making believe that the headpin was the captain and smack him right in the nose. That was the closest we could get to actually doing it."

It is, to most everyone, a social get-together. Dee Carl is Bennie's female counterpart, the secretary of the D.C. Women's Bowling Association, and she sees bowling as "a team sport, so it's a cooperative effort. It's a lot of fun. The people are nice, and there's a lot of camaraderie."

What does how we bowl tell us about ourselves? We can only speculate on the body language of each bowler's personal style. One athletic type will approach the foul line in a disco dance that ends in a taut statuesque pose when he releases the ball -- and he pauses, as a bronzed bowler on a trophy, waiting, waiting for the ball's verdict when it reaches lane's end. Then there's the coaxer, leaning over the foul line, her hand still beckoning after the ball's gone, as if by continuing to cup her fingers, she'll coax the ball into the pocket, the sweet spot to the right of the headpin that gives a strike. A compulsive type keeps everything straight: straight arm, straight back, straight ball.

Even the most blase bowler becomes victimized by form, and like a compulsive gambler, will try to effect the same stance and approach time and again, after it once gives him a strike.

Some use little tricks to help them concentrate, like always picking up the ball with the same hand, or wiping the hands on a rag after every single roll. But, Bennie says, "Some people don't concentrate at all. It's reserved for the high average bowler. With an average under 150 or 160, they're just there for an evening's fun, but as far as the actual concentration is concerned, they couldn't care less."

He allows as how he has a little trick, though. "I find the spot. I look at it and take a deep breath, and I hold it in till the ball goes."

Even how people react to stress might show up in their game. Ray Rosenman, a California cardiologist, warned against the effects of stress on the heart in a book he coauthored, "Type A Behavior and Your Heart." The idea is, relax and enjoy life and you'll live longer. The Type A personality -- the one that's filled with all those nasty feelings of time-urgency and internal pressures -- "often prefers watching highly competitive impact sports," says Rosenman. "When they indulge in sports themselves they are far more competitive. Type A plays the game to win, even when he plays with his own little children, and justifies it by saying they, too, have to learn to be competitive in a competitive world. B's are far more likely to let a child win.

"In bowling, A's are more in league bowling and they are highly competitive. A's would be much more observant of what everybody else is doing, including scoring accuracy. Bowling at a family level would prevail much more among type B's -- husband and wife, father and children."

Above all, bowling can be addictive. One recent sunny afternoon, a 13-year-old from Alexandria named Jeff Work, a bowling addict in the making, was inside the smoky Bowl Dine off Shirley Highway. He was throwing strikes. "I admit it's great out there in the fresh air, but if I get a chance to go bowling," he declared with all the enthusiasm of his youth, "I am going to go bowling."

The writer herself once bowled -- every single night for an entire summer. I didn't save much money for college, but they were giving away a free dish for every three games, and by summer's end, I had accumulated an entire service for six.