TULSA, Oklahoma - The largest BMX racing event in the history of the sport is happening right now in Tulsa.

It's the culmination of 28 events held all over the country this year. The USA BMX Grand Nationals run through Sunday at the River Spirit Expo.

It is non-stop, intense action for not only the competitors, but also for the fans.

Competitors are in Tulsa from all over the country. There are more than 4,000 amateur entrants who represent 45 states and 15 countries.

A lot is on the line, their top six scores throughout the year, and their finish at Tulsa's Grand Nationals count toward their year-end national ranking.

"The culmination of a national summer tour,” competitor Chris Emma said.

Emma, from Boulder, Colorado, enjoyed the sport as a kid, took about 35 years off, and now is involved again at 52.

"The adrenaline, at the end of it… and when you do well and have success as well it's just icing on the cake,” he said. “But just coming out here with all of your buddies, hanging out and bumping elbows and competing."

More than 60 age group titles on the line at the event held this year in Tulsa, starting at 5 years old and going past 60.

"It's really fun, really energetic,” Massachusetts competitor Anthony Lucchesa said. “It's like going on a roller coaster ride."

And when the roller coaster of a race starts with the sound of the horn and the gate dropping -- it's pure adrenaline.

"It's almost like a blur when you're going as fast as you can,” Arizona competitor Evan Boone said. “A lot is going on during the races."

And it's also fun for the fans who come to see round after round of races.

"Everybody cheering for you and everybody coming up and saying like you did amazing, it just feels great,” Californian Jayden Wenck said.

About 800 truck loads of dirt were brought to the River Spirt Expo at the fairgrounds.

The track is 1,050 feet long.

And the action is non-stop.

"It's really exciting because you get a few crashes here and there, and there's a lot of big air jumping,” Connecticut competitor Matt Webb said.

It's free to watch the competition, except for Saturday evening when the Pro Championship Finals take place from 5 p.m.-9 p.m. on Saturday. Tickets for that event are $10.