Philadelphian Elizabeth Robinson starts her summer vacation Tuesday in Languedoc-Roussillon, a small town in southern France. There, just 10 kilometers from the Mediterranean Sea, she and husband Frederick own a stone house with walls four feet thick that dates from the 1300s.

Regional wines are plentiful. So are cheeses, stews and escargot dishes.

Amid that gastronomic bounty, what will Robinson be focused on? Getting you to lift, run and crunch (as in abdominals, not chewing) your way to a more fit physique. Her larger goal is to propel her fledgling, as-yet-unprofitable, audio-based workout business, VitFit, closer to its goal of one million subscribers and $9 million in net revenue by the end of 2014. The company currently has about 1,500 clients and three part-time employees.

Robinson's success will depend in large measure on the market she has yet to penetrate — fitness clubs — embracing what her company does rather than considering it competition.

"Ultimately, you will see if not VitFit, something like VitFit, in every club in the next five years," Robinson predicted.

What VitFit offers is customized workout programs that provide audio coaching on a mobile device. In the crowded fitness-product market that already includes web-based trainers and workout apps, VitFit offers comprehensively what is available only piecemeal or not at all, those in the industry said.

"It really is a hidden jewel," said Rick Caro, a health-club industry consultant and founder of the International Health, Racquet & Sportsclub Association.

Through, VitFit assesses clients' fitness levels through a series of questions about cardio performance and muscle strength and flexibility, and then inquires about their goals. Based on the responses, exercise programs are prescribed, with subsequent adjustments made — such as number of repetitions or treadmill speed and incline — based on follow-up online questioning from VitFit once workouts begin.

In her sales pitches to clubs, Robinson has emphasized that her audio workouts can augment their members' regular trainers, freeing up those trainers to add more clients — a financial boon for the club. On average, clubs get only 10 percent of their members to buy personal-training services, Caro said.

VitFit is a plus for the club members, too, Robinson said, because they can have the equivalent of a trainer each time they want to work out — without the added cost.

Typically, personal trainers cost $60 to $125 a session — on top of what, around Philadelphia, is a monthly gym membership fee of $200 or more. VitFit will cost a fitness-club member $15 a month, or $20 a month for those not affiliated with a gym.

"It's a win-win-win," Caro said. "The member gets a win, the personal trainer gets to leverage themselves out between sessions … and the club gets a more consistent number [of members] who continues to be committed to the value of exercise."

All fitness clubs and trainers working with a VitFit participant will get a cut of the action. Robinson said her business plan calls for participating clubs to keep $5 to $8 of each VitFit membership fee. "We're paying them for warm leads," Robinson explained. From that, $1 to $2 is to be routed to the trainer working with a VitFit member. VitFit will match the club's payment to the trainer, Robinson said.

"It's important the trainers understand we're behind them," she said during a recent interview at the Philadelphia Sports Club near her home in the city's Spring Garden section, where she has taught fitness classes and hopes to forge a VitFit partnership. "They're really our boots on the ground."

Sneakers, actually.

How Robinson, a 40-year-old mother of one, wound up in a business sector where such footwear abounds started when her work life involved heels and business attire. She was in institutional equity sales at Janney Montgomery Scott L.L.C. in 1999, commuting from Philadelphia to Los Angeles, San Francisco and Denver weekly. Exercise became "the one consistent thing" in what was a life of ever-changing locales, she said.

Fast forward to 2008, when she closed a business-development consulting venture she had started after leaving Janney in 2002 and shifted "full throttle into this fitness stuff." She became a personal trainer after four years of teaching fitness classes in Philadelphia.

What she soon realized as a trainer is that she could help only so many people in a day. That amounted to six because her schedule required being present when her son, Dakin, now 8, got home from school.

Something else troubled her: leaving her clients without a trainer while she was away in France each summer.

That's when she thought of putting their workouts on audio recordings that included her voice urging them through 45 minutes of exertion.

They were well-received by clients who got the benefit of Robinson's coaching daily, if they wanted, without having to pay her a daily training fee. Funded with $50,000 from outside investors, VitFit was officially launched for alpha testing in 2010, with its first users signing on in India, Australia and the Pacific Northwest.

"I just put it out there on the website," Robinson said of her marketing, calling the robust response that followed "a little shocking."

Kinks were worked out — mostly technical in nature — and Robinson started offering it to fitness clubs last year. One club chain in Boston is currently testing it, while negotiations with others continue, said Robinson, who is again fund-raising to build on the company's momentum.

Among the VitFit converts is Jenna Folk, 31, of Philadelphia, who typically travels for her work in restaurant marketing one week a month. At home, she belongs to three gyms and, when not traveling, does VitFit three times a week as she prepares for a marathon in October. She does it more often when she's on the road "because group exercise classes aren't an option."

Referring to Robinson as "the coach in your pocket," Folk sees endless prospects for VitFit. "With social media and the online community, the sky's the limit," she said.

Given the growing number of clients and the time it takes to record workout programs — about four hours each — Robinson no longer personalizes the programs, but has developed enough of a library "to accommodate many needs," she said.

Later this week, she will begin adding to that inventory — recording from the third floor of her house in France.