The Rock ’n’ Roll USA Marathon route winds through the heart of Washington. (Competitor Group Inc.) The Rock ’n’ Roll USA Marathon route winds through the heart of Washington. (Competitor Group Inc.)

When Adam Doherty takes off along with the rest of the elite runners at Saturday’s Rock ’n’ Roll USA Marathon, he’ll just look like another blur of limbs. But the 23-year-old will be the only one of them guaranteed to nail a personal record.

How come? “I’ve never run a marathon before,” says Doherty, who graduated from Dartmouth College last year. That 26.2-mile distance is a goal that’s been on his mind since high school, when Doherty’s coach told him that a marathon would play to his strengths. Since then, he’s been busy competing for his school teams — mostly in the 3000 meters and 5000 meters — and has never had the time to train for one.

Now that Doherty is a working stiff in Charlottesville, Va., the opportunity presented itself. And he had another motivation that should sound familiar to anyone who’s ever signed up for a race: “I wanted to find something to help me stay in shape.”

The Doherty approach, however, isn’t exactly the typical training program. For most first-timers, the aim is just to get to that finish line. Doherty is shooting for a specific — and exceptionally speedy — time. He’s aiming to do it in about 2:30, which could win the race.

Adam Doherty Adam Doherty

He isn’t working with a coach, although he has gleaned tips from his college teammates and former Dartmouth coach Mark Coogan, who competed in the marathon at the 1996 Olympics.

“In the past eight years of running, I’ve gathered what I should be doing in my training,” Doherty says.

That’s translated into waking up every morning, usually before dawn, and logging some mileage. Recently, he’s added in a second daily run to boost his overall volume. And, once a week, he tackles a long run (the longest: 21 miles). It all adds up to about 80 miles a week.

So Doherty is ready to go the distance, even if he is a bit anxious about Saturday.

“The big worry is you get out there and feel good — 15 to 20 miles even — and then things can go south,” he says.

If that happens, Doherty will know exactly how he can redeem himself: Sign up for another marathon.

The Rock ’n’ Roll race (both the marathon and the half) starts Saturday at 7:30 a.m. But the fun kicks off at the accompanying Health & Fitness Expo at the D.C. Armory. The expo, which will be held Thursday from noon to 7 p.m. and Friday from 10 a.m. to 7 p.m., is open to the public. For more info, visit