Mary Lou Johnson, 42, beat attorney Colleen Barney, 50, out of the blocks (left) in the 100-meter dash, but both won age-group golds. Track and field was one of six USA Masters Games sports contested in late June. Photo by Ken Stone

Hill Carrow likens his USA Masters Games to a 21st century startup — but also a quadrennial event that began in 1896.

Hill Carrow is CEO of USA Masters Games via his Sports & Properties Inc. business in Cary, North Carolina. Photo by Ken Stone

The first modern Olympics were a “relatively modest multisport event in Athens, Greece,” said Carrow, CEO of the “national sports festival for adults” resuming Thursday across San Diego County.

To promote the Summer Games, he said, the International Olympic Committee piggybacked the 1900 and 1904 world’s fairs in Paris and St. Louis.

“They literally staged a sport per weekend” in the middle of the six-month fairs, said Carrow of North Carolina. “So they used what was then the biggest event in the world to get some legs under the Olympic Games.”

A year after the first USA Masters Games — an 11-day event in Greensboro, North Carolina — the second edition has modest goals amid Olympian ambitions.

Predicted last October to host 5,000 athletes 21 and over in 24 sports, San Diego 2017 is expected to end up with under 2,000 entrants. Carrow’s goal: break even financially.

Kids volunteered at the long jump pit at UCSD for the USA Masters Games. Photo by Ken Stone

(But he boasts registrants as old as 93 from 10 nations on five continents. Entrants are traveling from 35 states plus Australia, Canada, France, India, Mexico, Netherlands, Palestine, China and Uganda.)

“We’ve got challenges,” Carrow said several Sundays ago, watching the finale of the Masters Games track meet at UC San Diego. “It’s going to take us several iterations to get the Games up to where it should be.”

One hiccup this year was having to split the Games in half — with six sports (softball, soccer, bodybuilding, tennis, triathlon and track) contested in late June. One reason was to avoid having the track meet on the same July date (this weekend) as the USA Track & Field National Masters Championships in Baton Rouge, Louisiana.

Carrow, with help from organizers of the California State Games, also combined the Masters Games triathlon with the San Diego International Triathlon at Spanish Landing Park West.

Eighteen sports will host athletes starting Friday, including archery at the former Olympic Training Center in Chula Vista, swimming and diving at the Alga Norte Aquatic Center in Carlsbad, baseball at UC San Diego and basketball at the Salvation Army Kroc Center.

Competition also is set in badminton, bodybuilding, cycling, figure skating, ice hockey, judo, pickleball, powerlifting, a 5K road race, synchronized swimming, table tennis, volleyball, water polo and weight lifting.

But Carrow, a lawyer with a history of putting on major sports events, saw a silver lining in June’s soft opening.

Volunteers and officials — and athletes — could rest and come back for Phase 2, when “all hell breaks loose and you’re trying to put your thumb in the dike,” he said.

Another 2016 forecast may not come to pass — a 2018 San Diego edition.

Carrow’s original vision was to hold the USA Masters Games every other year in even-numbered years. But staging San Diego this year threw off the calendar.

“Maybe it takes two full years to get the word out and really market it the way it should be,” said Carrow, 62, a former collegiate swimmer who helped grow masters swimming.

The international market for masters games is crowded — with events in Australia, Europe and Asia plus the biennial National Senior Games and annual Huntsman World Senior Games in Utah.

But Carrow sees an unfilled niche — postcollegiate athletes in their 20s who don’t have a chance at an Olympic-style environment until their 30s (or 50s in the case of Senior Games).

“We have a ton of great adult athletes,” he said. “Let’s get together and celebrate them. …. We want to try to help that [younger] group have a segue … a natural continuation of their sport.”

A longtime masters athlete himself, Carrow adds: “I’ve always felt that adult sports get kind of short shrift. It seems nobody pays that much attention, but it’s really important.”

He doesn’t think his event will cannibalize others. In fact, he argues he’s helping grow individual sports. (Entrants have to be members of their sport’s governing bodies to compete at USA Masters Games.)

KUSI’s Dave Scott interviews Gary Patton, 71, who won the 800, 1500 and 5,000 in the two-day meet. Photo by Ken Stone

“There’s nothing proprietary,” he says. “We’re all about trying to kind of share the wealth, and the rising tide lifts all boats.”

After witnessing the triathlon just before the June 25 track meet, Carrow said: “We’ve maybe indoctrinated a fair amount of the eastern United States last year, and now we’re having to do grass-roots marketing. You can’t afford to have a giant advertising campaign.

“So we’re still a startup. We just need to keep building up awareness and interest — and our brand. … It’ll take a few years.”

Also a few beers.

While celebrating “adult health and fitness and wellness,” Carrow thinks “relationships that are built … are really essential.”

So besides parties, concerts, beer tastings (and a Padres-Giants game Saturday), Carrow offers a “kickoff party” at Dave & Buster’s in Mission Valley on Thursday.

“San Diego’s brewpub scene is just as much an attraction as great sports venues, unsurpassed weather, and wonderful tourist destinations,” Carrow said.

“We’re biased towards Southern Hospitality, but San Diego has proven the community can go toe-to-toe with any locale when it comes to being a welcoming, hospitable, fun city.”

The Opening Ceremonies are Friday at Qualcomm Stadium, with a scheduled “key note” by Olympic swimming legend Janet Evans, followed by events including parachute jumpers and Polynesian dancers with a fire show.

Torch runners will lead to a lighting of the cauldron, followed by fireworks.

The Closing Ceremony is a party Sunday at Park and Rec in University Heights.

It isn’t a cast of thousands a la the Summer Games, but Carrow still thinks big.

“What people now consider one of the most successful events ever invented — it wasn’t all easy to start with,” he said. “And we have the same thing.”