It happens every four years, when gymnastics is on primetime television for a week straight during the summer Olympics.

Parents suddenly enroll their children - mainly little girls - at their local gymnastics center with visons of a gold medal slung around the child's neck a decade later.

Gym owners and coaches call it the "Olympic effect."

This year, it's more like an Olympic gold rush at Monmouth Gymnastics, where New Jersey's breakout star and 16-year-old double-medalist Laurie Hernandez trains with the MG Elite team.

"The phone's ringing so much, it's actually getting comical," Monmouth's manager Christine Mellas said.

Many fall classes are full, they're getting 100 emails a day requesting information and they're begging coaches and instructors to work extra days this fall session. And they're chipping away at a rolling batch of 50 voicemail messages.

"I've been here for eight years and I expected it, but nothing like this," she said. "I don't know if we were truly prepared."

Mellas said they have enrolled about 200 extra children since Hernandez - dubbed the human emoji - rocketed to fame as a member of the gold medal-winning Final Five women's gymnastics team.

They expect more too when families get back from vacations and summer ends. "Right now, I cannot even squeeze one more kid in," she said of one of their class sessions.

Mellas said one little girl's uncle arrived at the Morganville gym in person and paid for the entire year in full because his niece promised him: "I am going to go to the Olympics."

Most of the surge in enrollment is for classes for toddlers, who take class with their parents and they start as young as 15-months.

And the gym's even had to deal with some upset parents, standardly late in enrolling their returning kids for the fall, who did not get the class time they expected.

In addition to the spike in enrollment, Mellas said they've had some interesting moments recently.

One mother drove 90 minutes from North Jersey just to show her daughter where Hernandez trains, she said. The mom started off the encounter with, "I hope you don't think I am crazy, but..."

Through it all, Mellas said the gym staff, coaches and parents have been proud of Hernandez for years, and many have known for some time that she was on her way to world-class competition. "It's been very exciting and we're very proud."

As for the last week and half, "It's a wild ride here, and it's been pretty fun too," Mellas said.

At other New Jersey gyms, the Olympic effect has started, just not at Monmouth's pace.

Tony Gehman, owner of North Stars Gymnastics in Boonton, started coaching at the gym in 1979 before buying it in 1985.

The Olympic effect, he said, started in 1984, when Mary Lou Retton captured the country's first all-around gold medal at the Los Angeles games.

He said that success elevated competitive gymnastic teams from rented spaces in church basements to profitable businesses with their own facilities.

And with the Rio squad putting up the best medal performance by an American team ever, many gyms will profit.

And it can be gradual, picking up once the games end this weekend.

Gehman has an open house scheduled this Saturday, where the competitive team will show off their talents.

"We're having the normal effect now, but were going to get (an increase)," Gehman said. "It's gonna happen."

At schools like the Gymnastics and Cheerleading Academy (GCA) in Cherry Hill, and ENA Gymnastics in Paramus, Rio successes are already translating into more kids signing up.

"And everybody's happy about it," GCA director Steve Tobin.

"Every Olympic year we get a huge benefit, and this year there's been an uptick," said ENA co-owner Craig Zappa.

Tobin said the gym his parents started in 1974, sees anywhere from a 15 to 25 percent increase the fall after a summer games, "Even if the team doesn't do so well," he said.

"This team did amazing though," Tobin said.

Tobin said more than the competitive side, the spotlight that gymnastics gets from the networks broadcasts really lets parents with kids who "roll around the floor and jump around the house" that there's a program for them.

"The general public does not really understand gymnastics training, and lot of the times we help them with the 'How do we get them involved?' questions," Tobin said.

"There's a real positive effect on schools," Tobin said.

Kevin Shea may be reached at kshea@njadvancemedia.com. Follow him on Twitter@kevintshea. Find NJ.com on Facebook.