Kerry Allen knows what it’s like to go to work on only a few hours of sleep. The legislative assistant for Sen. Amy Klobuchar, D-Minn., is up every morning before sunrise to log miles as part of her training plan for the upcoming Boston Marathon. Even on days when she does double-digit-mile runs, Allen is at her desk in the Hart Senate Office Building by 9 a.m.

“Depending on the length of the run, I’m usually out the door by 6 or 6:30 a.m. on weekdays,” said Allen, who qualified for Boston with a time of 2:56 at the Raleigh Oaks Marathon in North Carolina, where she was the fifth overall female finisher. She’s aiming to finish the 26.2 mile race in 2:48, which is an average 6:25-minute mile.

Allen will be joining 36,000 other runners at the 118th annual Boston Marathon on Monday, April 21. Expected turnout is near an all-time high for the race, eclipsed only by the 100th anniversary 18 years ago. The Boston Athletic Association increased the field size by 9,000, anticipating greater demand given the bombing that killed three people and wounded more than 200 last year.

“The energy last year was amazing and I can only imagine that will be amplified greatly this year,” Allen told CQ Roll Call. “I’m sure the race will be very emotional for both runners and spectators.”

Rep. Kyrsten Sinema, D-Ariz., will also be at the starting line, along with an estimated 800 from the D.C. area, according to information provided from RunWashington, a website and magazine.

Finding Time to Train

The frenetic pace of Congress and the intense daily training a marathon requires are a delicate balancing act. Even with a supportive boss and co-workers, the sheer miles required (Allen runs between 55 and 60 miles a week in peak training) means devoting a substantial amount of time to hitting the pavement.

“You have to fully know the time commitment required, plan well and stay flexible,” said Matt Lehner, communications director for Sen. Mary L. Landrieu, D-La. Lehner ran Boston in 2011 and qualified again for 2014, but decided against running. “My boss has her own competitive race this November that is keeping me busy,” he said.

Lehner has already qualified for Boston 2015 with a 2:50 at the Medtronic Twin Cities Marathon in Minnesota. During the peak of his training, he runs more than 70 miles a week.

Both Allen and Lehner are members of the Capitol Hill Distance Project, competitive runners who train Friday mornings on the National Mall. Allen is also a member of Georgetown Running Club, an elite team that sets out Wednesday evenings, though she admits the timing “sometimes is hard to make when the Senate is in session.”

Getting In

Unlike other races that rely on lotteries or open registration, the Boston Marathon reserves most of its spots for competitive runners who meet qualifying times for their age groups. The fastest runners have an opportunity to sign up before others. And the race fills up fast.

“Years ago they didn’t have quite as many runners that cared to go Boston. That’s changed,” said Charlie Ban, editor-in-chief of RunWashington. “If you’re a marathoner, people ask you if you’ve run Boston. And most people will want to say yes. It’s about as much of a gold standard in marathoning as you can get.”

More than 3,000 runners who met the qualifying times and applied were denied entry. The BAA reserved spots for the nearly 6,000 runners who were forced to exit the course last year immediately following the bombing, and an additional 5,500 spots for “non-qualifying” runners who have earned entry by raising money for charity.

Count Sinema in that bunch. The congresswoman is running for “Team MR8,” a charity established in memory of 8-year-old Martin Richard, killed in the 2013 bombings.

Boston will be Sinema’s 10th marathon — including a full Ironman in November. Her personal record is 4:29 from the Arizona Rock ‘n’ Roll Marathon in Phoenix, which runs through her congressional district. Sinema compares marathon training to a daily task like showering and brushing her teeth. “I do those things every single day. I treat training the same — do it in the morning when you get up, even when you don’t want to, until it becomes just another habit. Training for the Boston Marathon is way easier than training for the Ironman.”

Boston Strong

The staffers who spoke to CQ Roll Call anticipated high emotions in running the race. None seem daunted by the additional security measures, which prohibit runners from bringing personal items with them to the starting area in Hopkinton, Mass. Any clothes discarded before the race starts will be donated to charity, and if a runner wants to bring a phone or set of keys, it must fit into a fanny pack, with exact dimensions set by the BAA.

“The Boston Marathon is already one of Boston’s greatest days,” said Scott Zoback, district press secretary for Rep. Jim McGovern, D-Mass. Zoback is running the marathon as a non-qualifying charity runner with the Brigham & Women’s Hospital Marathon Team. “I’ve wanted to run Boston for several years. Having been on Boylston Street when the bombs exploded last year, this [year] was the right time for me to run.”

For those not running, it’s still a momentous event to follow. Instead of sitting on muddy tarps in the Runners Village this year, Lehner will be tracking his fellow Capitol Hill Distance Project runners via text messages at his desk. “The marathon is bigger than one day, one race or one course,” he said. “The Boston Marathon represents the enduring resilience and capacity of the human spirit to overcome and succeed.”

An earlier version of this article misstated which year Matt Lehner qualified for the marathon and the date of this year’s race.