Ben True knows the stakes. So does Becky O’Brien.

And Lauren Forgues. And Anna Pierce, Ben Shorey and Riley Masters.

The U.S. Track & Field Olympic Trials begin today in Eugene, Ore., and, for a handful of Mainers, the chance to earn a berth in the 2012 Summer Olympics in London.

“One of the reasons you compete in your sport is to reach for the highest level,” said True, who will compete in the 5,000 and 10,000-meter runs. “And the Olympics are the highest level in our sport.”

The Trials will start with the hammer throw on Friday and conclude on July 1, when Forgues and Pierce will make their bids for the team in the 20-kilometer race walk and 1,500, respectively.

Of course, track and field isn’t the only sport in the Olympic spotlight. The U.S. Swimming Olympic Trials will be held June 25-July 2 a the CenturyLink Center in Omaha, Neb. Five Mainers will compete in those Trials, headed by James Wells of Phippsburg and Cheverus High School and Jenni Roberts of Sanford.

The U.S. Rowing team held its Trials last week and will announce its Olympic team on Friday. Eleanor Logan of Boothbay Harbor won a gold medal as a member of the women’s eight crew at the 2008 Beijing Olympics and is likely to be part of that boat again.

It is, for all the athletes competing, time to shine.

“I’m on track to do what I have to do,” said Cumberland’s Becky O’Brien, who will compete in the shot put and discus. “I haven’t felt this way since I’ve begun college. In high school (at Greely) I was able to perform my best when it really mattered.

“I feel ready to perform my absolute best and give everything I have.”

O’Brien took the spring semester off from competing for the University of New York at Buffalo to prepare for the Trials. She returned home to train in early May.

“I’m the most confident I’ve been in my training in years,” she said. “I was able to focus and get everything right. I had the right support system in place, which is very important.”

O’Brien trained with her father, Dennis, who was her coach in high school, and enlisted the help of Greely classmate Adam Copp in her regiment. Her qualifying throws will put her right in the middle of the competition, but O’Brien is ready to make a statement.

“Competing in the Olympics has been a dream long before this year,” she said. “I’ve made a lot of sacrifices, I’ve dedicated my whole life to it.”

True knows what she speaks of. He probably enters both his races as an underdog — he’s got the seventh-best qualifying time in the 10,000 and the eight-best in the 5,000 — but is ready to earn his spot in the Olympics. He feels his best chance is in the 10,000.

“I’m definitely doing this with the goal of making the team,” he said. “I feel like I’m right there with them. Whatever way the race is run, I feel I have a good shot of being there. All those guys in the race, with the exception of Galen Rupp in the 10k, I’ve beaten at one time or another in the last two years.

“I’m confident I can beat them one more time when it really matters.”

The 10,000 will be run at 9:45 p.m. (Eastern time) Saturday.

Forgues is hoping for a better showing that the 2008 Olympic Trials, when a knee injury forced her out of the race. She enters with the fifth-best qualifying time but feels the race is wide open.

“All of us are at the point where any of us can win,” said Forgues, who grew up in Boothbay.

She has been training in San Diego. “I’m pretty excited because this is the first Olympics Trials where I’m actually a contender,” she said. “But it’s also nerve wracking because I am a top contender. I’m putting a lot of pressure on myself.”

Her race starts at 10:30 a.m. on July 1.

Shorey, the Ellsworth High School graduate, failed to qualify for London in the 50-kilometer race walk — which is his strongest race. His last chance this year comes in the 20k racewalk, which is 10:30 a.m. on June 30.

“That’s all I train for,” said Shorey, of the 50k. “I don’t train for the 20k. I expect to finish. But there’s no way I’m in shape to be in the competition, there’s no way I’ll walk the standard.”

Pierce, who competed in the 3,000 meter steeplechase in the Beijing Olympics, is attempting to come back from a disappointing 2011 season in which she battled illness. She’s got the fifth-best qualifying time in the 1,500.