NEW YORK (Reuters) - Time, money and the Internet are changing where Americans work out, fitness experts say.

Time-pressed fitness fans seeking short, focused workouts are flocking to boutique studios specializing in everything from indoor cycling to boot camp, and the no-frills gyms that burgeoned during the financial recession are still thriving in the recovery.

Cedric X. Bryant, chief science officer with the American Council on Exercise, believes fitness has taken a minimalist turn that encourages smaller venues.

"From a training perspective, we're going back to basics, away from more complex equipment," he said. "The simpler exercise approaches of popular trends like boot camp and CrossFit and High Intensity Interval Training require less space and less sophisticated equipment."

All of which, Bryant said, lends itself to economically sized, and priced, gyms. He expects the trend to continue because the workouts are effective.

"Time is always a big barrier for folks, so there will always be this lure to the minimal," Bryant said.

Nearly one in five Americans is a health club consumer, according to a 2014 report by IHRSA, the International Health and Racquet Club, an industry trade association.

While membership has remained more or less steady, IHRSA reports a shift in the past few years from large multipurpose clubs to smaller gyms, boutique or sport-specific studios and fitness-only facilities, many of which are franchised.

In the realm of no-frills gyms, Planet Fitness, which charges just $10 a month, is arguably king.

The company's chief executive officer, Chris Rondeau, recently announced the franchise had reached a milestone of 5 million members systemwide.

"I always say we're selling pizza, they're selling cheeseburgers," said Rondeau. "We're geared to the first-time exerciser, the beginner, as opposed to the more fanatical exercisers and the body builders."

To keep the price low, Planet Fitness has no personal trainers, daycare, pools or spas, and there are no group fitness classes and no plans to add any.

"We're keeping true to our low price point," Rondeau said.

Cost is the number one reason both men and women cancel gym memberships or refrain from purchasing one at all, according to IHRSA's 2014 trend report.

Even the big-box gyms are getting into the franchise game.

Donna Cyrus, senior vice president of programming at Crunch fitness centers, which has its own franchise model, Crunch Essentials, said these days there are many more options at lower price points.

"More people go to McDonald's than dine at higher-end restaurants," said Cyrus, adding that people just don't have to think that hard about spending $10 a month. "They forget it's even on their credit card, she said.

Cyrus believes the financial downturn was the tipping point. "That's when people started saying to themselves, 'They're taking $80 a month out of my Visa and I never go,'" she said.

Cyrus said the downside of cut-rate gyms is service and space. "You must keep the programming very limited," she said. "There are only so many treadmills, and often only one studio or one room."

Cyrus attributes the rise of the specialty studios at least partly to the time constraints of the Internet age.

"One-stop shopping is why small spaces are doing well. It's often the least amount of time for the maximum workout," she said. "These days you want to consolidate because the time you're exercising is that much time you're off Facebook or Twitter or whatever."

But she noted that many successful one-note studios are beginning to diversify, with indoor cycling venues adding barre classes and yoga-based programs.

"They are getting out of the box that people went to them for in the first place," Cyrus said. "When it's only one modality something is lost."

Cyrus, who has been in the business for 20 years, says fitness is like a wave: "It's like fashion. It comes and goes."