"Hercules" is so littered with absurdities, cinematic as well as mythological, that it's difficult to single out the most representative example of defenseless dumbness. Writer-director Lewis Coates, a name to inscribe at the top of your Z list if you contemplate investing in a movie spectacle, leaves himself and an all-too-obliging, ponderous prop of a star, muscle-man Lou Ferrigno, open for nonstop ridicule.

At one point our attention is drawn to a magic potion called Black Lotus, whose nectar allegedly "numbs the mind and inflames the senses." Following this helpful standard of comparison, the movie itself must qualify as a Gray Lotus, since it ingeniously contrives to numb the mind and dull the senses. Unless you're in the market for a $4 nap, the Ferrigno edition of "Hercules" has little allure.

In its shoddy, immobilized way the production may be a unique labor of love. At any rate, the publicity material insists that Steve Reeves, the vastly more persuasive and heroic movie Hercules of a generation ago, was a boyhood idol of Ferrigno. Unfortunately, the inspiration hasn't rubbed off in photogenic respects. Ferrigno's monstro physique is diminished by a stiff posture and a duncelike screen presence, attributes that place him in the same class with the obscure lunks whom Reeves outclassed in his time by presenting a far handsomer, looser figure to the camera.

Planted like some gigantic, inexpressive obstacle of sculpture in the middle of dinky sets decorated in funny pastels, Ferrigno looks better qualified to impersonate the giant in a semi-animated remake of "Jack and the Beanstalk." One doesn't really expect brilliant line readings from him, especially in a script that limits the hero's verbal scope to questions like "Another one of your tricks, witch?" or "Why am I stronger than other men?" or "What?"

Moreover, the production is so execrably post-recorded that every voice sounds hollow and disembodied. Nevertheless, the slowness of Ferrigno's reaction time when called upon to utter one of these nifties or to show intense emotion by, for strenuous example, furrowing a brow or letting out an audible exhalation, tends to place an extra burden on lifeless, resourceless moviemaking.

Coates has two paralyzing methods of staging scenes. If there are actors involved, they tend to appear in long shot and slowly approach the distant camera. If he's working only with the miniature set models, the camera ambles toward them for a poky, disillusioning overview. Given pictorial schemes this inert, the old ambience cannot afford too much deliberation and brooding from the members of the cast.

Evidently a patsy as well as a novice, Ferrigno doesn't seem to realize that he needs, at the very least, to protect the credibility of his muscles. The chintziness of the operation undercuts the illusions meant to illustrate Hercules' fantastic strength. It's not particularly impressive when Hercules manhandles monsters that are obviously harmless little plastic toys or swings a Styrofoam rock so hard that the tissue-paper walls of the set begin to shake. A graceless, heavy object himself, Ferrigno doesn't pretend to lift or shove heavier objects with much flair or trace of humorous satisfaction. He's like a grimly earnest furniture mover.

No one asks a movie Hercules to sound like Plato, but if his feats of strength look laughable, the whole enterprise is bound to be stigmatized as a fraudulent bad joke. Curiously, there's a silly-looking stunt that more or less sums up Ferrigno's inability to carry this burdensome vehicle: Hercules is shown playing ox, cutting three parallel furrows with a yoke rigged to three boulders, but the progress is so painfully slow that you wish someone would tell the poor clod that he might get further plowing one furrow at a time with a more streamlined blade.

The plot is a mythological mishmash that garbles the legend of Hercules with goofy cribs from Ulysses, Moses, King Arthur, "Clash of the Titans" and other promiscuously scavenged sources. The principal "thread" is Hercules' attempt to rescue a kidnaped harem princess called Cassiopea (Ingrid Anderson) from a nasty tyrant, King Minos (William Berger), and his merciless henchslut, Arianna (Sybil Danning), whose almost totally exposed breasts seem to be deployed as a satiric affront to the star's overdeveloped and totally exposed pectorals. This kind of face-off was always a reliably hilarious aspect of muscle-man epics, so at least "Hercules" gets one mirthful element right. HERCULES

Directed and written by Lewis Coates; director of photography, Alberto Spagnoli; production manager, Victtorio Galiano; edited by Sergio Montanari; music by Pino Donaggio; produced by Menahem Golan and Yoram Globus. An MGM/UA-Cannon Group Inc. release. Rated PG. THE CAST Hercules . . . . Lou Ferrigno Circe . . . . Mirella D'Angelo Arianna . . . . Sybil Danning Cassiopea . . . . Ingrid Anderson King Minos . . . . William Berger