The first rule of playing James "the hardest working man in show business" Brown on stage is this: Never let them see you sucking air.

The pressure is even more intense when you're also responsible for aping the smooth moves of Michael Jackson and the legendary pelvis of Elvis.

It's a good thing, then, that Jonathan Kaina, a founding member of the Society of Seven Las Vegas, has the moves, the muscle and the cardio to ensure his impressions leave an impression.

Kaina works six nights a week with the Waikiki showroom group. In addition to his singing and comedic skills, Kaina plays saxophone, drums, guitar and bass. Throw in a few wardrobe changes and he might be more James Brown than James Brown.

"Actually, James Brown is easy," says Kaina, 41. "He just screams. And the Elvis I play is laid-back. The hardest one is Michael Jackson, because he's known for his dancing. Every night, I tell myself: 'Think Michael. Think Michael. Think Michael.' "

It's not easy. In addition to thinking Michael, James and Elvis, Kaina, a volunteer football coach for Damien Memorial School, must also occupy his mind with pops, slants and hitches.

At Damien, Kaina, the former offensive coordinator for the middle-school team, works closely with quarterbacks and wide receivers, drawing on his own experiences as a multisport athlete in high school to educate and motivate his charges.

Like other Damien coaches, Kaina is more than willing to show the kids how it's done. He regularly joins the players in running and agility drills.

"It lets them know that, hey, I'm 40, but I can keep up with you," he says. "If I can do it, you can do it."

He takes the same approach to whatever he does, be it coaching Pony Division baseball in Makakilo or instructing young martial artists on the finer points of kempo karate.

Kaina's twin passions for sports and music go all the way to his beginnings in Maui.

As children, Kaina and his two brothers played every sport they could think of, especially baseball, Kaina's first passion.

At Lahainaluna High School, Kaina excelled in baseball and track, but it was football that ignited his hormone-addled engines, and he starred as a running back, backup quarterback and occasional safety.

"It's when you start hitting guys that you realize, 'This is fun!' " Kaina says. "Baseball is just hitting a ball."

Kaina found similar satisfaction a decade later when he started getting serious about kempo karate. "I got into it more when I couldn't play football anymore," he says. "It offered the same kind of contact and aggression. It was big back then, and everybody got into it for the same reason: to hit someone."

For all of his athletic exploits, Kaina still found time to nurture his musical gifts, talents passed to him by his father, Peter, and his uncle Albert, both accomplished musicians.

For 12 years, Kaina forged his own musical identity as a member of the band Honolulu. In 2001, he was recruited by the original Society of Seven's Tony Ruivivar to join a new, younger offshoot of the group: SOS-LV.

Together with Glenn Miyashiro, Johnny Fernandez, Jan Luna, Richard Natto, John Salvatera and Freddy Von Paraz, Kaina has helped SOS-LV build on the SOS identity, in the process becoming a reliable draw in Waikiki.

"It's a fun gig," Kaina says. "I can't complain."

But sometimes his cohorts can.

In one standard bit, Kaina dances with Miyashiro then jumps over his head. For five years, they performed the stunt without a hitch. Then, Kaina says, during a performance earlier this year, "my crotch hit his forehead.

"I don't know if it was me," Kaina says, "or if he just didn't duck."

Kaina's exertions on stage and on the practice field are the midlife equivalent of two-a-day practices, but Kaina doesn't stop there.

Whenever possible, Kaina hits the weight room, where he performs dedicated workouts for his chest and shoulders. He makes a point of working his biceps and triceps every session because "every day of your life you use your arms."

To keep his legs in top shape, Kaina does a few squats and many, many lunges. He also makes time to run, usually 20 to 30 minutes at a time, progressing to basic running drills and ending with a set of six all-out sprints. This gives him the lung power to "ugh!" like James Brown, even after leaping not-so-tall Miyashiro in a single bound.

For Kaina, it doesn't matter which came first, the boundless energy that allows him to live an active life or the active life that feeds his boundless energy. For him, it's all about good health and good living.

"I get excited just going to practice, just throwing and catching the ball," he says. "There are people my age who go on and on about 'could have' and 'should have.' Just go out and play!"

Reach Michael Tsai at mtsai@honoluluadvertiser.com.