Katharine (Kat) Holmes, the second-ranked fencer in the United States, spars with Zsombor Garzo last month at the DC Fencers Club. (Jonathan Newton/The Washington Post)

On the strip, they tend to look the same: a white protective jacket with matching knickers; a long epee, weighing about 1 1/2 pounds with a blade measuring 43 inches; and a mask that obscures each fencer’s identity. The difference between competitors is usually found behind that mask, said Kat Holmes, the second-ranked epee fencer in the country.

“At the highest level, for the most part, everybody’s strong, everybody’s fast, everybody knows all the actions,” Holmes said. “The biggest differentiator is the mental game.”

The 22-year-old District native is a neuroscience major at Princeton who is likely bound for the 2016 Olympics. She has been fencing since she was 9, when she stumbled across “The Song of a Lioness” series by Tamora Pierce about a young girl in medieval times who pretends to be a boy to become a knight.

“I was like, ‘Oh, I want to sword fight, too!’ ” Holmes said.

Katharine (Kat) Holmes, the second-ranked fencer in the United States, works out as she prepares to compete for a spot on the 2016 Olympic team. (Jonathan Newton/The Washington Post)

Holmes’s parents enrolled her in lessons at Chevy Chase Fencing Club, and something just felt right. “I was the worst in my class,” she said, “but I just really enjoyed it.” A dozen years later, Holmes is ranked No. 22 in the world and is enjoying her best season on the international circuit.

She has taken a break from her studies to prepare for Rio. Holmes, a graduate of National Cathedral School in Northwest Washington, appears to have all the physical tools to reach the Summer Games: She’s 5 feet 10, strong with quick reflexes. Her edge, she hopes, lies elsewhere.

While she trains on the strip six days a week, she works on her mental game around the clock. Away from the sport, she works as a research assistant at the Princeton Neuroscience Institute, studying all manners of human decision-making and reasoning. There are plenty of applications to her sport, but recording the data and plugging it all into a mathematical formula isn’t so simple.

“You can’t stick somebody in full fencing gear in [a functional magnetic resonance imaging] scanner,” she said. “But many of the things we talk about in the lab are experienced within the sport, like making decisions in a split-second where you’re not really consciously making the decision.”

A fencer — or any athlete, really — might practice an action over and over until it becomes second nature. For Holmes, this might mean studying an opponent’s tendencies and training her body to react accordingly. Studies show that simply visualizing an action can promote brain activity that mirrors the actual exercise.

“So if we say that we’re just going to think about fencing, those same neurons will fire, and in the same way a muscle gets stronger the more you use it, the more the neurons fire, the stronger the neuronal connection gets,” she said.

Along with her Princeton coach, Zoltan Dudas, Holmes will study hours of video of each opponent, and using a program called Dartfish — also used by soccer, hockey and basketball teams around the world — she will tag different movements and actions. They will log much of what they see into a spreadsheet and search for trends. An opponent might take two small steps before lunging, for example. Or she might tip whether she’s about to feint or attack. Like a seasoned card sharp, Holmes tries to identify all of these cues and prep a response for each. “It’s kind of like a war plan,” she said.

“I will literally visualize myself fencing them, visualize what actions I’ll take when they do this or that,” she said.

Dudas and Holmes have paid particular interest to likely Olympic foes. They have identified 70 percent of the expected Rio field and have spent the past 10 months studying and analyzing those competitors.

“Our goal is not just to be at the Olympics but try to do the best possible,” Dudas said.

Dudas said Holmes has been eager for instruction and patient to see results. Small tweaks in technique or strategy sometimes take months to reveal themselves on the strip. Just last month, competing in Nanjing, China, Holmes bested Germany’s Britta Heidemann, who won gold at the 2008 Games and silver four years later in London. As Holmes has progressed in the sport, the Olympics morphed from a dream off in the distance to an obtainable goal. All that separated her was her own effort and growth.

“It’s always been real to me. It’s always been something that I felt I could grab, that was in my control,” she said.

Even when she was younger, she was motivated by setbacks and pushed by goals.

“I was always amazed at her work ethic,” said Raymond Finkleman, Holmes’s coach at the Chevy Chase club, “not only in fencing. She’s very smart, and she always worked hard. Whenever we were traveling, she’d always be studying on the trains or planes that we were taking.”

Competing for the Princeton team, Holmes took bronze at the NCAA championships as a freshman and placed fifth as a sophomore. But in each of those seasons, she entered NCAA qualifying tournaments on crutches, injuries to a knee her freshman season and an ankle her sophomore year. She could barely walk but insisted on competing. Holmes was in tears — particularly her freshman season — but turned in strong performances and qualified for the NCAA tournament. Teammates had to carry her to the bus afterward.

Holmes completed her junior year in spring 2014, finishing seventh at the NCAA championships. Rather than try to juggle her studies and senior thesis with Olympic qualifying, she opted to take a two-year break from school. Holmes serves as a volunteer assistant coach at Princeton. She trains for six to eight hours most days, working individually with coaches, training with the Princeton team and traveling to New York three days a week to work out at the New York Athletic Club.

No matter what happens in Rio, she will return to classes afterward.

“The Olympics is not something you want to half-ass,” Holmes said. “I really want to do this, and I want to do it right.”