Jenny Hoffman made a last minute decision to embark on a new attempt to run across the United States, coast to coast, in pursuit of a world record. A physicist at Harvard University who studies the properties of insulators and conducting materials, she turned to the time-honored method of recruiting students willing to help. In just two weeks, she gathered an enthusiastic team to accompany him along the way, supplying him with food, water and emotional support.
Hoffman took a break, left her lab under the care of a senior research scientist, and set off from San Francisco on September 16, 2023. Her 3,000-mile (4,888 km) route took her through California, Nevada, Utah, Colorado, Nebraska, Iowa, Illinois, Indiana, Ohio, Pennsylvania, New Jersey and New York. Sleeping in a camper van that followed her along the way, she averaged more than 100 kilometers a day as she navigated highways with narrow shoulders, storms, dogs and even large pieces of farm equipment that nearly drove her off the road. .
Just 47 days, 12 hours and 35 minutes later, Hoffman arrived at New York City Hall. In the last kilometers, she was accompanied by dozens of friends, family and fans. Her time broke the previous women’s record by more than a week. She returned victorious to Harvard’s physics department in Cambridge, Massachusetts. Less than a month later, she flew to Taiwan to compete in the 24H World Championships, an international 24-hour race in which she placed 23rd in the world.
Embracing the challenge: combining marathon training with graduate studies
Now, Hoffman is back in the lab, writing grant proposals in an office her colleagues have decorated with balloons and trying to regulate her metabolism after consuming 8,000 calories a day during competitions. She’s also trying to decide on her next big goal, which may not be an athletic one. “You can have a scientific impact, but you can also have an impact by being a good mentor or giving someone the confidence they need to do a hard thing,” she says. “People’s influences are probably more accessible to me now.”
Many scientists would worry that the intense training required to achieve an extreme athletic goal would affect their research results. But Hoffman is no slouch. Her laboratory has published dozens of papers, including one in science last March about quantum oscillations in a type of insulating material1. She mentors students in her lab and others, and attends numerous conferences. “I don’t think there’s any compromise in any dimension of her life,” says Daniel Lieberman, an anthropologist at Harvard who studies the evolution of human athleticism and runs with Hoffman every Tuesday morning. “I don’t think she sleeps.”
Hoffman insists she sleeps — about seven hours a night — but says running is a necessary function of life. “It’s just part of the self-care I do every day,” she says. “Even if you have a grant due tomorrow, you’re going to brush your teeth, right?” Tracking her time and looking for ways to make things more efficient helps, although she admits she doesn’t have time for a social life beyond her husband and three children.
She often worries that she is neglecting either her career or her sports activities. “There’s this myth of having it all or doing it all and you can’t,” she says. “I’m definitely not as good a physicist as I would be if I didn’t run, and I’m not as good a runner as I would be full-time. But you only get one life, and I don’t want to throw any of these activities away.”
Running has been a part of Hoffman’s life for more than 30 years, although she only began to pursue it seriously in 2014, after the birth of her third child. She never expected to be successful. But she soon found herself winning ultramarathons — races that are 50km, 100km and longer — and her goals became increasingly difficult. Her 2023 run across the United States was her third attempt, following a particularly heartbreaking attempt in 2019 when she injured her knee with just 800 kilometers to go.
Teamwork makes the dream work
The latest run couldn’t have happened without a lot of teamwork, Hoffman says. During the most intensive two weeks of training, the amount of time she spent in the lab was cut in half, but she trusted her group of about 30 people to continue the science. “I’m really lucky to have a great group of students who work together as a team really well and they’re able to turn to each other for questions and advice,” she says. The team, she says, was used to working without her being physically present as a result of the COVID-19 pandemic, and her senior scientist was able to fill in for her, handling the issues.
The training and running itself also required a team, which included Hoffman’s husband as well as massage therapists and a professional logistics coordinator, along with a support team drawn from students and old friends. Among them was Yanting Teng, a Harvard physics student who signed up to drive Hoffman’s support van in Iowa and Illinois. Teng was particularly impressed with Hoffman’s drive to reach her next stopping point each day and her willingness to push further if she wasn’t satisfied with her progress that day. “If she wants to do something and feels good about it, she’ll go for it,” Teng says. “I’ve never seen anyone so determined.”
Determination can be the key to being a good ultrarunner—and a good scientist, Hoffman says. “You have to be okay with repetition to be successful in the lab, and sometimes you have to repeat a task many times to get it right,” she says. “I think the same kind of mentality applies to long-distance running.”
Science itself supports this assessment. Although little research has been done on ultrarunners, Lieberman says mental toughness and pain tolerance are the most necessary traits, in addition to good form and endurance. The human body evolved to run long distances instead of short sprints, he says, but land mammals did not evolve to run Hoffman’s average of 101 kilometers per day. “No horse can do what Jenny did,” he says. “You would kill the horse.”
For Hoffman, long-distance running is not only a personal challenge, but also a necessary escape. Many people with demanding careers find that they think more clearly when they run or exercise, describing it as a chance to clear their minds and think about problems in a new way. But Hoffman says she never thinks about physics while running. Instead, she listens to audio books.
In fact, Hoffman says, the objective nature of the sport puts her day job into perspective. “Human judgment plays a big role in science and much less of a role in running, so I really appreciate being able to do something where someone else’s opinion doesn’t matter,” she says. “There are no anonymous reviewers. I just run the time I run.”