THE FIRST INTRODUCTION to bodybuilding for most people is the Mike Marvel advertisement on the inside cover of Superman comic books. Once a year, ABC's Wide World of Sports features a bodybuilding context as a novelty. Even a Harvard student won some notoriety last year as an "artist sculpting my body." He won some title like "Mr. College America" after the initial winner was disqualified because he attended a regrigerator repair school. Although bodybuilders and competitive weightlifters are popular in Europe, Americans have little respect for those who throw the steel around.

In spite, or maybe because, of these preoccupations, Pumping Iron is an entertaining film that disappoints what would be common expectations for a bodybuilding flick. Although not a muscle beach spectacular featuring Mike Marvel and his "he-man" friends (in six weeks you can look like this or your money back), the film also would disappoint anyone hoping for an incisive psychological examination of why men would suffer so much pain to deform their bodies. In quasi-documentary form, Pumping Iron cleverly hypes bodybuilding and its main character, Arnold Schwarznegger.

At 6 ft.-2 in. and 240 pounds, the Austrian born Schwarznegger has won the Mr. Olympia contest, the world professional bodybuilding championship, six times. Despite the relative merits of his sport, Schwarzenegger acts like the champion he is. With his cocky banter and waggish smile, he resembles Broadway Joe at the height of his career. Schwarzenegger describes the pain of tearing his muscles and the narcissistic pleasure of competitive posing, and beams, "It's as satisfying to me as coming." Since he screws, works out or poses constantly, he claims, "I am coming day and night. I'm in heaven."

THE FILM'S first half centers on Mike Katz, a former New York Jet and amateur bodybuilder. Katz says he always felt a need to "prove myself" and be feared on the football field. As with Schwarzenegger's sexual pleasures, director George Butler loses another opportunity for deeper analysis. An aging jock, with puka beads, a double-knit leisure suit and the hair from the back of his head combed over his balding pate, Katz comes across as an archetypal bodybuilder.

The amateurs' contest merely serves as a warm-up for the battle between saucy Arnold and Lou Ferrigno. Ferrigno comes closest of all the film's characters to fitting the stereotype of a refrigerator repairman. A simple 6 ft.-5 in., 275 pound kid from Brooklyn, New York, Ferrigno's strength bewilders him. His father, a retired New York City policeman, coaches, mothers and worships his boy who is "just like something Michelangelo carved." At the championships in South Africa, Schwarzenegger easily outpsyches Ferrigno. Ferrigno is so child-like and yet imposing, it seems at any moment he is going to ask George to "tell me 'bout the rabbits."

MOST SCENES SHOW the bodybuilders working out or competing. Schwarzenegger lifts with the boys at Joe's Gym in California and Ferrigno lifts at a less elaborate club in Brooklyn. A few obligatory scenes of Schwarzenegger posing for advertisements with bikini-clad models, riding horses and posing on mountaintops, sans shirt, and Ferrigno eating dinner with his family alleviate the monotony of the bodybuilding process.

Schwarzenegger, of course, thinks bodybuilding is " the greatest sport in the world" and the participants deserve credit for their efforts. Their daily regimen involves complete devotion to excruciatingly painful workouts and strict high-protein diets--some bodybuilders eat 40 egg-whites a day. Builders are judged on their size, shape and body symmetry. But despite Mike Marvel's claims, they are deforming their body with no other end in sight besides posing. The film never explores the real reason for this distorted vanity, preferring to just glorify it.

Pumping Iron was a low budget film and director-producer Butler is not a major film figure. Last September, after the film was rejected by several Hollywood studios, Bobby Zarem, a New York press agent, started pushing it and Schwarzenegger. Chic crowds have frequented the openings in New York and Boston (at the fashionable Institute of Contemporary Art). Schwarzenegger, who aspires to an acting career, has even had his portrait done by Jamie Wyeth. Financially, Pumping Iron is doing quite well.

Despite its obvious shallowness, the film entertains because it panders to an innate fascination. In Richard III, Shakespeare described King Richard III as a man so ugly that people could not help but look at him. Pumping Iron appeals in a similar vein. After the first few scenes of rippling flesh, one easily becomes immune to the bodybuilders' gross distortions and enjoys Schwarzenegger's charismatic overconfidence. A guy from the refrigerator repair school may have suffered disqualification in a collegiate contest, but another mechanic has made a movie that entertains, but does little else.