SAN JOSE -- Ethan Rozak is a newly crowned national taekwondo champion.

On Sunday at the convention center, the tall 13-year-old from Mansfield, Texas, just south of Dallas, won two matches by 47 combined points, to reach the finals of his division. He then won his last match to top his division in an 11-10 nail-biter, but it wouldn't have been close if he hadn't lost 8 points for hitting too hard.

"I like combat," said Rozak. "It's always been fun, especially when you win."

Rozak's win followed by two days that of his dad, Eric. Both are blue belts, a middle rank in the Korean martial art. But the younger Rozak has been training for three years, while his dad's been at it for just a year.

Rozak was among the 4,900 or so competitors representing all 50 states who were taking part in the annual USA Taekwondo national championships. The event not only determines the sport's best competitors, but is also part of the selection process for the U.S. national teams, which represent the country in the Olympics.

Anyone accustomed to visiting the convention center for trade shows or car expos wouldn't have recognized the place this weekend.

Instead of booths touting the latest set of wheels or high-tech whiz-bangs, the center's three conjoined halls were filled with two rows of bench risers separated by two rows of exercise mats. Instead of the buzz of convention chatter, you had outbursts of cheers and shouts -- and the occasional tear.

Instead of adults dressed in suits or business casual, you had parents and coaches clad in neon-colored jackets or shirts with intricate logos promoting their kids' studios. And there were hundreds of kids in martial arts uniforms on the mats breaking square wooden boards, performing intricate choreographed movements -- and kicking each other.

Single-elimination

Sunday was the sixth and penultimate day of the competition, with the spotlight on kids ages 12 to 17. The competitors each took part in one or more of three events: sparring, which is a controlled fighting event; board breaking; and poomsae, also known as forms, in which they perform a strenuous series of preset movements including crisp and stylish punches, blocks and kicks. In order to participate in the tournament, contestants had to have competed in or, in some cases, have placed first through fourth, in a state contest.

About 60 percent of the competitors were taking part in sparring, according Jason Poos, the vice chair of the tournament committee for USA Taekwondo. Each sparring match consists of three one-minute rounds. Competitors score points by kicking their opponents' heads or kicking or punching their chests. The person with the most points at the end of a match is the winner.

The tournament is single-elimination, so if you lose, you're out. The competitors are divided into groups according to gender, age, belt rank and weight. That so much of the tournament was devoted to sparring was just as well for many of the competitors, who, like Rozak, were particularly enthused by that component.

James Beckles, 13, of Chesapeake, Va., has been taking taekwondo lessons for nine years and has been a black belt for five of them. He says he doesn't love the sport but sticks with it because he enjoys sparring. He likes that each opponent is different and he has to change up his attacks to confront each one. He loves the screaming of the crowd. And he loves one other thing.

"You get to kick a guy," he says.

Lot of fun

Like Beckles, Sacramento resident Ilene Vue loves sparring. Vue, 12, is a red belt who has been training for about four years. She was a national champion last year and Sunday afternoon was anxiously awaiting her first match. Although she also qualified for the poomsae competition, she was looking forward to the fighting.

"I like having fun with another team and learning another's techniques," she said.

To be sure, there are other, nonmartial reasons the competitors take taekwondo. For Annabriza Melchnor Barragan, of San Jose, it's just a great social event.

"I get to meet a lot of new people and compete and cheer for my team," said Barragan, 12.

Many of the parents seemed enthused with the sport, too -- and not all that concerned with all the kicking and hitting on display.

Houston resident Casey Kagan was at the tournament to cheer on his son, Daniel, 14. Half joking, Kagan, 43, said that at the numerous national and state tournaments he'd attended, he'd never seen anyone die. Meanwhile, he likes the lessons the sport imparts about such things as respect for country and elders, patience and honor.

"I think that those are good things to teach my kids," he said.

Contact Troy Wolverton at 408-840-4285. Follow him at Twitter.com/troywolv.