Trainers search for the bizzers’ next tone zone

Crystal ball murky on next trend

Great fitness trends are like blockbusters. Given all the right elements — cast, crew, location, timing and topic — it’s still the audience that turns them into a cultural phenomenon.

Take spinning, the Holy Grail of fitness trends. Developed in the late 1980s by Venice denizen Johnny G, it could burn 500 calories in 40 minutes, race a heart to 90% of its capacity, and was as easy to do as riding a bike. It inspired the opening of specialty studios like Revolution Fitness and YAS. It caused Gold’s Gym and Equinox to devote entire rooms to the stationary bike.

And when tales of burning thighs and sore saddles became points of pride swapped at the watercooler, group cycling officially morphed from fad to fitness staple.

It’s a prototype professionals like Matt Ribb, assistant manager at the Sports Club/LA in Beverly Hills, try to tap into when they create the classes offered at their clubs.

“There’s only so much you can do on a bike,” he says. (The Sports Club/LA offers at least four classes a day.) “We’re realizing now it’s about the core and balance and the mind-body connection. Everybody’s looking for the next big thing.”

However, the crystal ball is murky. In a town where working out trumps both sleep and lunch, there’s no shortage of classes (and requisite hot-bodied trainers) worth the hour of sweat. But pinpointing the one that will launch an accessories line is still a crapshoot.

For Ribb’s money, it’s Indo-row. Essentially spinning with rowing machines, it’s total body fitness that requires you move in sync with people in your row, like teammates in a boat.

“If you do 1,500 meters on a rowing machine, your ass is on fire,” says fitness guru David Kirsch, author of “The Ultimate New York Diet.” Kirsch keeps celebs like Liv Tyler and Heidi Klum in shape using an integrative “nothing that bloats” diet and a series of 10-minute express workouts.

Those who take 10 minutes just to motivate themselves to get off the couch may prefer packing a complete body workout into a single shot. Burn 60 in Brentwood combines an hour of group walking, jogging or running on treadmills, punctuated with free-weight training. It’s strenuous fitness, if anyone was paying attention.

“We’re talking about image-driven people with crammed schedules; they all bring the ego in,” says Michelle Lovit, an exercise physiologist and trainer at Burn 60. “The morning classes of industry wives are quite a scene.”

Sweat and snark certainly help pass the time, but a fitness trend is only as good as it makes your body look. For Karen Genendlis, director of sales at Gold’s Gym in Hollywood, that means lean and toned, not steroid stuffed.

“The ‘big, big’ thing hasn’t worked for 10 years,” she explains. “Someone in front of a movie camera isn’t looking to gain size, they want to look ripped.”

And get their daily dose of masochism while they’re at it.

“People in Santa Monica want to come in and get their asses kicked,” says Amy Dixon, group fitness manager at Equinox Fitness. “Exercise for some people is not fun.”