While sitting through his daughter’s two-hour gymnastics competition one day five years ago, Jeff Herdman was struck with an idea.

Rather than forcing parents to sit idle on uncomfortable folding chairs, he thought it would be great if they could get in some workout time while their kids were doing athletic activities.

“A light bulb went on in my head,” he said.

Little did he know at the time that that notion would spawn an entire business.

Herdman, 40, recently opened the doors to Hangar Athletic Xchange, or HAX, a 70,000-square-foot hybrid gym and basketball training complex. The facility features weight-training and cardio equipment, plus rooms for activities such as yoga and Pilates, all overlooking the centerpiece of the facility: six full-size side-by-side basketball courts.

“Obviously it’s nice watching your kids, but there’s no time for the parents to also work out,” said Herdman, a former college basketball player and the chief executive of HAX. “Here, they can be upstairs and run on a treadmill while also watching their kids work out.”

The athletic center, housed inside an old airplane hangar at tiny Hawthorne Municipal Airport, has seen its membership ranks swell to more than 400 in its first six months. The company expects to double that number by the end of the year. An additional 225 kids are enrolled in its basketball and volleyball camps, and HAX runs a variety of tournaments, leagues and other programs nearly every day of the week.

“It’s been great,” Herdman said. “I had a mom come in yesterday who said she heard about us through kids at her kids’ school and she came down and signed her kids up for a camp. It’s really growing that way.”

But HAX is proving to be more than just a family gym. The center has caught on with a number of National Basketball Association all-stars, who use the facility for practice and personal training. It’s not uncommon these days to see players such as Elton Brand or Paul Pierce heading for the nondescript building adjacent to the general aviation airport. Along one wall hang the jerseys of a number of pro basketball players who have visited HAX or sponsored camps at the facility.

What’s more, HAX has been the site of the predraft tryouts for the NBA’s D-League, a developmental league. James Harden, an Arizona State University player who was recently drafted third overall by the Oklahoma City Thunder, trained at HAX while preparing for the draft.

Herdman likes to think of the facility as the “the mecca of basketball in Southern

California.”

The center is not just about hoops, however. HAX has hosted a number of volleyball camps and tournaments, as well as mixed martial-arts events.

Katie Patton, who recently became a member, said she does not play basketball but she loves the gym’s other amenities.

“I was a bit intimidated going in there because I thought it was all about basketball,” said Patton, 22. “But it’s also good for people like me who don’t play sports.”

A typical membership costs $89 per month, while a high-end contract, which includes personal training sessions, can cost $149 a month, putting it in the mid- to high-end range among L.A. gyms. HAX offers discounts to for students and kids whose families cannot afford the standard rate.

In the current recession, many startups are finding the business environment to be unforgiving. In the health club industry, in particular, many gyms are watching their membership ranks decline as potential customers opt for lower-priced facilities or for no gym membership at all, said health club consultant Glenn Colarossi. Also, starting a new gym in an airplane hangar is a money-eating project; for example, air-conditioning the huge space in the summer could get expensive.

HAX is not yet turning a profit, but revenue primarily from membership dues, fees for tournaments and special events, plus rent income from leasing retail space has been on the rise over the past six months.

“We have increased revenue substantially,” said Jason Boze, HAX chief financial officer. He declined to discuss specific numbers. “We expect to be profitable by the end of the year.”

Team approach

Colarossi said facilities that offer play space for team sports such as basketball have an advantage over traditional health clubs, where members often exercise alone or with a single companion.

“When people are involved in team sports, they are bonded to the club, so they will probably stay,” he said.

Herdman, an imposing 6 feet, 7 inches, played basketball in college for UC Irvine. He went overseas for a few years with several European teams and even played for the summer league team of the NBA’s Milwaukee Bucks, but didn’t make the regular season roster.

But by the mid-1990s, Herdman was busy forging a new type of career for himself. He consulted for the Paul Frank clothing company and eventually partnered with Earvin “Magic” Johnson to launch a branded footwear and apparel line. He recently sold his share.

In 2004, he had the epiphany while watching his daughter do gymnastics that led him in a wholly different direction.

With his longtime friend and business partner Steve Burnett, Herdman started to formulate the idea of a facility that would offer athletic programs for kids particularly basketball and exercise equipment for adults.

One of the first problems, as with any new business, was money. Herdman convinced a longtime friend, Manhattan Beach doctor Michael Cooney, to back the venture. To date, about $10 million has been invested in HAX, mostly from Cooney.

The next challenge: location.

Herdman knew he wanted to have a number of basketball courts beside one another. But that proved impossible at the sites he visited because there were large supporting columns that couldn’t be moved and wouldn’t allow him to place the courts the way he wanted.

Herdman caught wind of the Century Business Center, a collection of large buildings including hangars next to the Hawthorne airport being marketed by Kearny Real Estate.

“They approached us with what we thought was a very interesting and very unique concept of converting it into this high-end athletic center,” said Hoonie Kang, a partner at Kearny.

Herdman bought the hangar in 2007 for $5 million, and got to work fixing up the old facility. He bought the courts from the NCAA, then had them dismantled, transported and installed at the hangar. He also arranged lease agreements with a caf & #233; and a footwear retailer.

Recently, the company has tried to spread the word through social networking, including a MySpace page and a recently activated Twitter account. Mostly, though, the company expects to grow by word of mouth.

Herdman said he expects the variety of amenities to appeal to families, which is already happening.

“If we can gear so that an adult is working out while the kid is working out, or they can sit at our caf & #233;, which has wireless Internet, and just be more productive with their time it’s a no-brainer,” Herdman said.

Hangar Athletic Xchange

FOUNDED: 2008

HEADQUARTERS: Hawthorne

CORE BUSINESS: Training center featuring basketball and volleyball camps for youths

EMPLOYEES: 25

GOAL: To become leading basketball-focused fitness center in Southern California

THE NUMBERS: Founders and Manhattan Beach doctor have invested $10 million to launch project