Alyson Hannigan

On a recent day here in Los Angeles, the sunny New York City set on a sprawling studio lot was a crowded place.

Dozens of extras clad in running gear and drenched in fake sweat ran by cameras for take after take, as technicians, makeup folks and scores of staffers milled around. Given the number of people on hand and the scope of the production, it looked as though a feature film was being made.

This is the set of a sitcom? A supposedly “traditional” sitcom at that?

The sweaty runners were participating in the back-lot marathon for a February episode of “How I Met Your Mother.” The CBS show about five friends in New York City, which manages to be both whip-smart and endearingly sweet, is part of CBS’ Monday lineup of mostly traditional, multicamera sitcoms. That term refers to shows that use up to four cameras at once to film a half-hour comedy in front of an audience on a soundstage.

Except we weren’t on a soundstage. And there was no audience. “HIMYM” does have a laugh track, but it’s inserted well after the show shoots for three solid days. Many traditional sitcom tapings last three hours.

“It’s definitely ... a lot easier than a one-hour [show], but it’s a lot harder than a traditional sitcom,” says Alyson Hannigan, one of the show’s leads. “People are like, `What do you mean, you need three days to shoot an episode?’”

A lot has been written about the supposed demise - and even the comeback - of the half-hour comedy on network television. Traditional sitcoms, we’re often told, are too stodgy and predictable and are just not cutting it anymore, while “single-camera” comedies such as “The Office, “My Name Is Earl” and “30 Rock” are all the rage.

But the line between “30 Rock” and “HIMYM” is not that distinct. Just as “Ugly Betty” isn’t quite a comedy and isn’t just a drama, “HIMYM” is something of a hybrid.

For one thing, some “single-camera” shows use more than one camera at a time. And though “HIMYM” does have a laugh track, the fact that the laughs (from a studio audience that watches a tape of the show) are put in after filming means the comedy is not “a slave to the audience” as executive producer Greg Malins says.

“You’re not writing to their reactions and writing to the lowest common denominator,” Malins said says. On other shows he has worked on, “any time you need to replace a joke and you just put the word `panty’ in there, the audience goes nuts. It’s hard to resist that.”

“I come from multi-camera shows. I love traditional hard jokes,” says “HIMYM” writer Jamie Rhonhiemer. “But with this show, we can do that and still tell emotional stories.”

“HIMYM’s” stories are told with more scope than many traditional sitcoms employ. A typical episode of “Friends” might have had a dozen scenes, maybe 18 at the most, Malins says. The “HIMYM” episode being shot last Wednesday had 53. The show’s pilot had 60 scenes.

“There’s no way we could shoot this amount of material in front of an audience,” says co-creator Craig Thomas. “It would blur the line between `audience’ and `hostage situation.’”

“You have more freedom to make it more visual” with a longer shooting schedule, Malins says. “The traditional way is that you take three hours, you just put it on like a play and shoot it. You could never do the stuff we do here.”

“The terms single camera and multicamera are vestiges of another era of TV,” says Carter Bays, the show’s other creator. “They’re pretty vague categories at this point. Every show is its own animal.”

Another “HIMYM” anomaly: Five of the show’s 11 writers are women, which is an unusually large number, especially for a comedy staff. And director Pamela Fryman has helmed almost every episode of the show.

Having a strong female presence on the staff was a conscious decision, according to Thomas, who, along with Bays, used to write for “The Late Show with David Letterman.” “At `Letterman,’ there was one woman on staff the whole time I was there, and she was only there for three months,” he says.

“We knew we wanted it to have heart, and not just be totally snarky,” he notes. “With too many dudes in the room, it just becomes this total insult-fest.”

Despite the things that make it distinctive and different, “HIMYM” is still thought of by many as a traditional sitcom. And the people behind the show are conscious of the fact that if they were perceived as a single-camera show, “HIMYM” - which is a steady ratings performer with an avid fan base - might be more of a media darling, and could even become a breakout hit.

“I kind of feel like we get lumped in with some tacky shows sometimes,” says staff writer Brenda Hsueh. Graf can trim

“If we were on NBC on Thursday, you’d realize quicker that we’re more like `Scrubs,’” Thomas says.

Though he’s a devoted fan of cult fare such as “Veronica Mars,” Bays says, quite simply, “I want it to be the big hit.”

And they’re trying to make that happen through traditional and new-media promotional tactics. “Dancing With the Stars” champ Emmitt Smith was on the lot that day, filming a scene for the episode that will air the day after the Super Bowl. And Bays says that during May sweeps, there will be a wedding on the show.

The creators also have their fingers crossed that “HIMYM” will turn up on iTunes soon (a deal to make that happen is in the works, Thomas says). The show’s ladykiller, Barney, has a blog on CBS.com, and a MySpace page featuring a music video from another character, Robin, in all her former glory as teen-pop princess “Robin Sparkles,” was a hit: Her video has been streamed more than 400,000 times since its debut.

After the Robin Sparkles episode aired and the MySpace site’s traffic went nuts, “we got some of our best ratings the next week,” Thomas says.

Still, don’t expect J.Lo-style stuntcasting anytime soon. The show will continue to be about friends who hang out at a bar and have hilarious and sometimes sad experiences in life and in the dating arena. Like the best sitcoms - single-camera or multicamera - it’s grounded in a funnier version of reality.

As “HIMYM” writer Kourtney Kang says, “A lot of our stories come from `Oh, God, you won’t believe what happened this weekend.’”

A few more bits and pieces from my “How I Met Your Mother” set visit:

* To film the “Robin Sparkles” music video, Cobie Smulders had to perform the song 40 times for the cameras. When she was finally finished that day, they brought a crepe cart to the set so she could have a crepe as a reward. She said that episode is her favorite thing she’s done on the show.

* The robot in the Robin Sparkles video sits in a place of honor in the “HIMYM” writers offices. It’s an Omnibot 2000 by Tomy, the same robot Bays wanted as a kid.

* In the February episode “Lucky Penny,” Barney ends up running a marathon, and the track suits that Neil Patrick Harris wore on Wednesday were quite fancy. He has one powder-blue track suit that was nearly blinding, with matching silver running shoes. He called the ensemble his “B. Diddy” look. Thomas says there was a big debate as to whether Barney would run the marathon in one of his regular “suit up!” suits, but in the end they decided that he could “track suit up.”

* In an effort to save money, the show decided to do one episode last year on one set - a limousine. It turned out to be a nightmare. “We never know what’s going to be hard for the production staff,” Bays said. “Shooting in a car was the most excruciating experience ever. We had to take it apart, it was so hard to shoot anything in there.”

* Bays dropped this tantalizing idea about Barney, when I asked whether he would ever have a steady girlfriend. “What if he had a girlfriend but he just wasn’t bringing her around?” Hmmm.