The Colossus of ‘Roids : MUSCLE: Confessions of an Unlikely Bodybuilder, <i> By Samuel Wilson Fussell (Poseidon: $18.95; 252 pp.)</i>

The way he tells it, Samuel Wilson Fussell used to be a pathetic ectomorph, a pencil-neck geek, a 6-foot-4, 170-pound weakling--the kind of guy bodybuilders contemptuously refer to as a “Norbert.” The spawn of a pair of intellectual Schwarzeneggers, food scholar Betty Fussell and Paul Fussell, author of “The Rhetorical World of Augustan Humanism” and “Thank God for the Atom Bomb,” Sam was a 26-year-old Oxford grad headed for a Ph.D. at Yale when he heard the call of the weird.

In “Muscle: Confessions of an Unlikely Bodybuilder,” Fussell tells how he fell off the academic track and into bodybuilding circles, which he describes in terms worthy of Dante. Investing his grandfather’s modest bequest in gym tuition rather than Yale, Fussell became a Norbert-no-more.

Each week he fueled a maniacal training regimen with a diet more excessive than Diamond Jim Brady’s--”70 eggs, 14 tins of tuna, 10 1/2 pounds of beef, 10 pounds of chicken, 9 gallons of nonfat milk, 4 loaves of bread, and as many sacks of brown rice, whole wheat pasta, baked potatoes and fruit as I could load into my shopping carts,” plus 826 BIG Chewable Vitamins providing up to 5,882% of his minimum daily requirements.

But man does not grow by bread alone. Fussell had a whole crew of new gym pals cheering him on in accents unaffected by literary study (though they did evince a certain fondness for Nietzsche): Titanium, the dead-lift champ of the Texarkana Federal penitentiary; Sweepea, a.k.a. “The Missing Link”; Mousie, the “Portuguese Rambo,” and the cyst-encrusted Vinnie, Fussell’s training partner, who sniffed ammonia and bled from either end while power-lifting--he bashed his forehead with barbells to get into the right spirit and induced mild chronic rectal hemorrhage by means of steroids. That’s half the reason the mighty man had to wear two thicknesses of Huggies in the gym. Even Cuddles the pit bull gym mascot provided a measure of moral support. At least, young Fussell had found a calling and a crowd he could call his own--imagine his folks’ delight! “These men have tits ,” protested Mrs. Fussell.

Her incredible expanding son would not have you believe that bodybuilding is all carob power-explosion bars and desiccated beef-liver tablets, however. No, it took dedication, masochism and the same indifference to boredom that scholars say is the sine qua non of literary research. Instead of hitting the books, he had Vinnie expertly hit him in the face to cause what the muscle mags call a Heightened Arousal Mode (i.e., anger), so he could hoist a bit more than he could have done without blood streaming down his face.

Vinnie also injected him with various anabolic steroids, a practice Fussell defends on the grounds that “To bodybuild without steroids was to read Russian literature in translation.” Granted, steroids had their down side: “Excessive use (of Human Growth Hormone, a steroid extracted from cadavers) promoted an unsightly enlargement of the jaw and forehead, the mysterious appearance of a gap between the two front teeth, the irreversible growth of the extremities (including the genitals), and, occasionally, sudden death.” But what’s an occasional death, or a woman with a monstrous mons veneris, or a man’s risk of what his pals dismissed as “bitch tits” (caused by the body’s estrogen reaction to testosterone onslaught) compared with the certainty of adding inches of too, too solid flesh on the biceps? Human Growth Hormone was, according to his colleagues, “the ultimate test of a builder’s commitment.” As Vinnie, ever the poet, put it, “Like the (expletive) orchid, ya bloom !”

Pretty soon Fussell was a bloomin’ lifter and stripped-down poser in heavy competition in Southern California, scrubbed down with Dye-o-Derm tan-on-a-sponge and jazzed up with Pearl Drops Tooth Polish. So what if they ran out of trophies in his first big competition at the Rose City Bench Press Extravaganza, and he had to take one home that read, “Women 148 lbs First Place”? The point was, he was a contender.

He also had a steroid-related problem with acne (“wherever I had skin, I had pimples”), pesky rectal bleeding, bouts of “ ‘Roid Rage” (irrational hormonal tendencies toward violence) and a brief liaison with a gym gal named G-Spot, who had a voice like a foghorn and no immediate likelihood of facing motherhood. By now he crushed the scales at 257 pounds; “Between the two of us, there was close to 500 pounds on that sofa, and when our grappling session began, you could practically hear the clink and groan of our armor.”

No question about it, Sam Fussell was a new man. Four years of perpetual training, barfing, bleeding and dieting sculpted him into a behemoth with an abdomen resembling an ice-cube tray. Strength was beside the point: “I couldn’t run 20 yards without pulling up and gasping for air. My ass cheeks ached from innumerable steroid injections, my stomach whined for sustenance . . . my face was drawn and haggard, my eyes the haunted sockets of a ghoul.” He was, in short, a pitiful, helpless giant--but the man had his pride.

Fussell didn’t waste his time as a musclehead. He did achieve the status of runner-up as Mr. San Gabriel Valley of 1988. And he did produce this book, boasting the liveliest prose concerning Atlas unbinged since Robert Ferrigno’s Southern California thriller “The Horse Latitudes,” in which ‘Roid-raging characters contribute an impressively sleazy atmosphere.

But “Muscle” has its flaws. The narrative is desultory, and Fussell grunts and strains for effects without ever clearly conveying to us his motive in changing shape. He mentions the physical peril he felt in mugger-infested Manhattan--an explanation that rings only partly true--and his unhappiness in love and that of his parents, which sounds more plausible. But he never really gets into self-revelation with the passion he devoted to growing his gastrocnemiuses.

In the first chapter he grandly says, “Of arms and the man I sing,” but we learn more about the former than the latter. When it comes to really leveling with the reader, Fussell just pumps irony.