Now it’s a niche winter activity generating interest both recreationally for adults and as a potential training tool for junior athletes who aspire to more elite levels of competition.

You could say the concept has taken off with a bang — but “pop’’ and “splat’’ more accurately describe the soundtrack of paintball biathlon.

“This thing has kind of taken on a life of its own,’’ said Bill Reuther, the Nordic ski coach at Rutland High School. “The kids get a huge kick out of it. It’s a gateway to get them into skiing and shooting.’’

Reuther, along with race organizer Mary Anne Levins and Roger Hill, the director of programs and facilities for Mountain Top Inn & Resort in Chittenden, dreamed up what is widely recognized as the first paintball biathlon competition in 2006, which drew a respectable number of locals from area ski clubs.

Now the sixth annual event has blossomed into a two-day affair with 340 participants, ranging from first-graders to senior citizens. The Jan. 22-23 paintball biathlon at Mountain Top will draw teams from across the Northeast.

“It’s now the largest youth biathlon event in the world,’’ said Reuther.

Organizers are proud their idea has spawned copycat paintball biathlons and even piqued the interest of the US Biathlon Association, which for decades has had difficulty cultivating new athletes because the sport is so inaccessible.

“It’s pretty neat, because there are others popping up all over the world,’’ said Levins. “Part of what we have to create is more localized opportunities for juniors. I think you’re going to be seeing and hearing a lot about biathlon in this country.’’

Traditional biathlon, which is dominated by Europeans, involves cross-country skiing interspersed with target shooting using small-caliber rifles. It blends all-out speed with calm, focused precision, and when shaping their paintball version, Reuther said his group tried to tweak aspects of the discipline to maximize youth interest while underscoring shooting safety.

Juniors do not ski the course with a firearm, like they would in an actual biathlon. Rather, identically sighted guns (paintball enthusiasts prefer the more sanitized term “markers’’) are left at each shooting station, and the firing range is monitored by adult volunteers.

Another difference is a positive — not penalizing — emphasis on scoring. Traditionally, competitors who miss targets must ski penalty laps. In paintball biathlon, skiers are rewarded with time deductions for every target they hit. Depending on age, youth courses range from 1 to 4 kilometers, while high school and adult divisions ski 5 kilometers.

Reuther said other incarnations of biathlon had been tried in the past to spark youth interest, but beanbag tossing just didn’t hold the interest of kids, and air rifles were considered too dangerous by parents.

“It’s a hard sport to get into,’’ said Reuther. “You’ve got to be a good skier, and on top of that you have to have a place to practice firearms.’’

Paintball manufacturers have been willing to donate the markers used at meets, because they know if the craze grows, a new set of customers will want to buy their own guns. And Levins is aware of at least two traditional biathlon ranges that have opened in New Hampshire and Vermont after organizers first spiked interest by holding paintball competitions.

“Kids are really excited about biathlon in general,’’ said Abby Weissman, director of youth and introductory programs for the New England Nordic Ski Association. “With kids, it’s important to get them started when they’re young, and to make it as fun and as challenging as possible.’’

And if aspiring paintball biathletes have what it takes to advance to the real deal, there’s a chance their skills will be noticed by someone in a position to help: Max Cobb, the executive director of the US Biathlon Association, regularly volunteers at the Mountain Top event, and he has taken an active role in supporting paintball.

“We have already had some young skiers come into the sport of biathlon because they participated in the paintball biathlon events,’’ Cobb wrote in an e-mail from Germany, where the US team was competing in a World Cup event earlier this week.

“It will be some years before we are able to point to international results, but I’m pretty sure we will see 2018 or 2022 Olympic team members who got their start at a paintball biathlon event.’’

Levins said that prospect is something she and the other co-creators of paintball biathlon at first did not envision, but now see as a highly plausible occurrence.

“That would be a dream for us,’’ said Levins. “To one day watch an Olympian on TV and be able to say he or she started right here at Mountain Top with paintball biathlon.’’