Summer sizzle: daring fare pushes the envelope as well as ratings.

A whole batch of cable nets -- from MTV, HBO and USA to FX, Comedy Central and Showtime -- are going for broke in trying to shake up their audiences this summer.

Take the current contingent of "Real World" young adults, who love to skinny dip in the swimming pool they share in Hawaii, giving the show a rating spike in its eighth season that has catapulted it into a regular berth in the Nielsen top 10.

Or the female predators of HBO's "Sex & the City." They've so captured the imagination of masses of viewers with their hard-R-rated bed hopping and witheringly frank sex talk that the show has entered the vocabulary, transcending the showbiz pages of the local papers and turning up regularly in news features about urban dating rituals.

Jedd Palmer, an attorney, TV consultant and former head of programming for John Malone's Tele-Communications Inc., says that when the average cable subscriber gets more than 60 channels of programming, there's no better way to "stand out from the crowd than to turn the camera on attractive, unclothed men and women. And violence in drama and sports always provides a vicarious thrill to TV viewers.".

Violence, although of a comic-book kind, has generated lively industry buzz for USA, which scored its best young-adult ratings ever for a series bow with "GvsE." This tongue-in-cheek action hour posits a Los Angeles teeming with dead people restored to life so they can use their borrowed time to hunt and kill the grotesquely evil characters who have gravitated to L.A. en masse.

And amateur boxers have begun beating each other's brains out every Friday night on Rupert Murdoch's FX, which doubled its ratings in the time period when the hour-long "Toughman World Championship Series" premiered July 23.

Not to be outdone, Comedy Central has unleashed a festival of political incorrectness with its Wednesday-night "Man Show," which unapologetically urges women to stop demanding equality and embrace the role of sexual plaything bent on nonstop heterosexual pleasure. The show is doing 68% better in household ratings for its first six weeks this year Wednesdays at 10:30 than the various shows that occupied the time period a year ago, and 116% better among men 18-34.

And Showtime says it's getting more requests for cassettes from showbiz people than ever before because of "Beggars & Choosers," a jaundiced look at the TV industry, which is trying to capture some of the flavor of the hit 1976 pic "Network.".

CATCHING ON"The cable industry is finally catching on to the fact that summer is the perfect time to put on more original programming and spend more money on hype," says Stacey Lynn Koerner, VP of research for TN Media, referring to the blizzard of repeats that fill the schedules of the broadcast networks during the hot-weather months.

Rod Perth, president of the Jim Henson TV Group Worldwide and former head of programming for the USA Networks, says, "Cable viewers are becoming increasingly aware that there's something going on beyond the purview of the broadcast networks. Above channel 13 on the dial, there are lots of innovative ideas that are grabbing the attention" of cable subscribers.

Cable networks insist that innovation, not exploitation, is the watchword of the shows that are making lots of noise this summer.

Brian Graden, exec VP of programming for MTV, says the resurgence of "Real World" actually took place last year, building up anticipation for the young men and women who signed up to share a house this season.

It's not only the brief nudity on this summer's "Real World" that has riveted viewers' attention, Graden says, but also the frightening alcoholism of Ruth, one of the women in the group. She's getting lots of publicity, but Graden regards the whole cast as "adventurous.".

With "Sex & the City," HBO is elated not so much because the show is becoming almost emblematic of the late-'90s mating dance among professional men and women, but because that image is translating into more viewers this season than during its rookie year of 1998.

An average of 8.1 million subscribers are watching at least one of the five weekly runs of each "Sex & the City" half-hour since its second season premiered eight weeks ago, compared to only 6.9 million for the same period last year -- a 17% increase, according to figures from Nielsen Media Research.

"GvsE," "Toughman" and "The Man Show" are all pulling a high volume of young males, many of them the ones who continue to make pro wrestling a monster hit on USA, TNT and TBS.

Cable networks keep targeting young adults because they're catnip to Madison Avenue's ad buyers. It's the men and women 18-34, in particular, who have absorbed cable into their bloodstreams and profess minimal loyalty to the broadcast networks that their parents were weaned on.

"The 18-34 audience came of age with cable," says Lynne Buening, VP of programming for Falcon Cable TV, a multisystem cable operator about to be taken over by Paul Allen's Charter Communications.

As Buening puts it, "If a cable network creates programming for that demographic, it'll get a head start in the race to cross the finish line with a ratings winner.".

Added material.

G VS R: USA's hit "GvsE" is bringing more comic-book violence to cable.

SEX TALK: Sarah Jessica Parker stars in HBO's sensual "Sex & the City.".

PUNCHING UP SHOWS: For Fox's FX nothing works like the "Toughman World Championship Series" with the key male demo.

HOOPING IT UP: Showtime returns to the basic appeal of sports to reel in young males.

UNREAL WORLD: MTV has been grabbing auds with its "Real World" showing bare bodies skinny dipping in Hawaii.