It’s the assembly-line workout.

Tucked away in mini-malls all over Los Angeles are tiny gyms like Ladies Workout Express, Curves for Women, Cuts Fitness for Men and Contours Express. These and other fitness franchises typically target a niche market usually women, sometimes men, who want a workout that lasts no longer than 30 minutes and aren’t interested in joining a larger gym packed with hard-bodies.

Generally, the gyms’ small size (1,000 to 3,000 square feet) and limited equipment keep overhead low. For a monthly fee ranging from $30-$70 (plus an upfront charge of $100 or less) members run a circuit of equipment that is arranged in workout order. There are often no showers, saunas or locker rooms.

The small-gym concept was launched in 1992 by Gary and Diane Heavin, who started Curves in Harlingen, Texas to help overweight women get in shape. They focused at first on smaller communities that didn’t have health clubs and on middle-aged women who were hesitant about customized workouts.

“He always had in mind that the conventional gyms were not targeting the market that his mother was in women 30 and up,” said Curves spokeswoman Becky Frusher. Heavin’s mother, who was overweight and suffered from high blood pressure, died at 40 from a blood clot a fate Heavin says could have been avoided with regular exercise.

As Waco, Texas-based Curves grew, it entered larger cities including Los Angeles, where there are now 22 outlets. Worldwide, there are more than 8,000 Curves and 4 million members, with an average age of 55.

Other chains have tweaked Curves’ approach to win more converts to the quickie workout. Still, the formula remains pretty much the same regimens designed to fit into a busy schedule with easy-to-use hydraulic machines often arranged for a circuit of exercising.

“There are tons and tons of these young, totally fit women who still want to get in their workout,” said Trina O’Bryant, who opened the Culver City franchise of Ladies Workout Express, which aims for a younger clientele.

There are five Ladies Workout Express locations in Los Angeles, and O’Bryant said more will open shortly. Ladies Workout Express is a branch of Lady for America, which has about 800 sites nationwide.

Men’s chains

The formula has been altered somewhat for men. “A lot of men are intimidated by an L.A. Fitness or a Bally’s,” said Jeff Jarred, owner of a Cuts Fitness for Men in Northridge. “There are no mirrors in here, and there are no guys standing in the mirror pumping their biceps.”

Jarred, who opened the Cuts Fitness in Northridge last year, said the gym has about 200 members ranging in age from 35 to 60.

The men’s gyms are having a harder time attracting members than the women’s, said Sumol Chomyong, who opened a Cuts Fitness for Men last year in Silver Lake where she now has about 100 members. “Somehow it is easy for women to do exercise compared to men,” she said. “It is hard to convince men to stick with what they are doing. They come and then they go.”

Frusher said that Curves has stopped opening new locations in many markets, including L.A. as much of its future growth is targeted abroad.

That leaves aspiring franchisees to choose from the newer chains.

“I like to see competition because it just reinforces the credibility of the category,” said John Gennaro, founder of New Jersey-based Cuts Fitness for Men. “There is enough clientele out there for several players.”

As for start-up costs, franchisees pay about $30,000 for initial instruction and equipment, plus royalty fees to the franchisor from about $150 to $600 per month. In addition, there’s rent, marketing and other expenses that can bring the total start-up cost to $80,000 to $100,000.

Franchisees said they generally need between 200 and 300 members per location to break even. They claim they retain more members than traditional gyms, which lose about 75 percent of their members each year and must replenish them.

Some of the gyms have extras to help target a specific niche. Ladies Workout Express has a sauna, for example, and a bathroom that is lavish compared to most bare-boned Curves.