When the air horn goes off for the 5K run at the 37th annual Moonlight Run & Walk on Sept. 17, Lupe Alcantar plans to be at the starting line in person with her two daughters and two sisters by her side.

The East Palo Alto resident said the return of the event at the Palo Alto Baylands represents one small step toward normalcy following a year of living in pandemic lockdown.

This is the first time in months Alcantar said she has felt motivated to return to running, a sport she's enjoyed for more than 20 years, despite a knee injury.

It's not about coming in first place or beating her own running time, the 44-year-old explained.

"It's just so much fun being out there with other people ... and I know I have to push myself because I don't want to be the last one," she said.

Vera Horiuchi, 67, also plans to be at the starting line surrounded by her extended family. The longtime Palo Alto runner has participated in the annual event with her family many times since the mid-1980s when her daughter, now 36, crossed the finish line in a racing stroller.

Horiuchi said participating in this year's 5K run seems to hold even more significance.

"I feel more inspired," she said. Running, she explained, represents the one thing that the pandemic didn't alter or take away from her.

"I feel really fortunate that I can still do my preferred exercise — pandemic or no pandemic," said Horiuchi, who has been an avid runner since graduate school. She runs or walks the same neighborhood loop along Alma Street and Churchill and California avenues on most days of the week, although she now avoids the pedestrian tunnel at the end of California Avenue as a safety measure due to the rise in COVID-19 cases.

"I like the feeling of running. It makes me feel a lot stronger," she said.

Alcantar and Horiuchi are hardly alone when it comes to heading outdoors to run: The sport has experienced a resurgence during the COVID-19 pandemic, with an estimated 50 million Americans, or about 15% of the U.S. population, participating in some form of running.

Data gathered over the past year from online athletic shoe review company RunRepeat points to a nationwide running boom. Since the pandemic, 28.76% of current runners are new to the sport, according to the company's 2021 Fitness Trends report, released on Aug. 6. More than half of active adults surveyed said running, hiking and exercising outdoors is one of the best ways they're staying fit in 2021, up 14.6% from the start of 2020.

Locally, Eileen Urtz, general manager for A Runner's Mind, an athletic shoe store with three Bay Area locations, including one in Los Altos, said she's definitely seeing increased interest in running and outdoor exercise in general.

Since California reopened in June, the company has seen the number of participants in its running groups triple at its San Francisco site compared to before the shutdown. The running groups at the Burlingame store are smaller than they were prior to the pandemic but have been steadily growing since June, with about 30 to 40 runners each, she said. The company hasn't started its running groups back up at the Los Altos site yet, she said. On a few mornings each week, however, there's a group of runners that meets independently behind the store.

"During the pandemic, people needed to get out of the house to exercise," Urtz said. "There was really nothing else to do, so suddenly, you have a lot of people getting out and running more often than in the past."

Urtz said the fact that a lot of people in the area are still working from home and have more flexible schedules could also lead to increased participation.

Urtz said Runner's Mind is a specialty running shoe store that conducts a full-gait analysis of customers to match them with the proper equipment. The process includes a lot of questions, so the business has good data on who is brand new to running and who has taken it up again in the pandemic, she said.

In general, more adults ages 20 to 50 are new or returning to the sport, she said.

In the past year, the company experienced such a surge in business with people looking to order running shoes online or calling the store to arrange curbside pickup, that Urtz actually had to temporarily give up running herself because she was too busy trying to meet customers' needs.

For Alcantar, the pandemic initially had the opposite effect on her running routine.

She said in the early months of the pandemic, she stopped running, partially because it was an activity that she and her daughters did as part of their training for the Moonlight Run, which they had planned to participate in in fall 2020 until the in-person event got canceled due to COVID-19. After that, they stopped training, and Alcantar turned to hiking — one of the only activities she did outside of her house during the shutdown, she said.

In recent weeks, with her dog by her side, she's been training nearly every day for the race, alternately walking and running the trails near Cooley Landing, Facebook and Dumbarton Bridge. Alcantar said she typically runs the 3.5-mile trail that loops along the perimeter of the Facebook campus, which is just around the corner from her home. Easy access to the trails has been an upside of working from home over the past year: It's made it much more convenient to get outside and enjoy the surrounding nature, she said.

Horiuchi said she's been content running her neighborhood loop and was happy to participate in last year's virtual Moonlight Run, but she's ready to get back out to the Baylands.

"I love doing the run," she said. "It's very special to (my family)."

Urtz said whether someone's running competitively or just for fun, "Running, and really any kind of physical movement, is beneficial for one's mind, body and soul. It's a good thing to do when you want to get out of the house and clear your head."

This year's annual Moonlight Run & Walk includes a 5K walk/run, 10K run and half marathon offered virtually and in person at the Palo Alto Baylands. The fundraising event benefits local nonprofits dedicated to helping kids and families on the Peninsula. For more information about the event, go to paloaltoonline.com/moonlight_run.