Diamondbacks’ Christian Walker walks barefoot on the stadium grass before games. Here’s why.

SAN FRANCISCO — Shoes off and dropped near the visitors’ dugout at Oracle Park, Christian Walker begins his barefoot stroll through the perfectly manicured grass and makes his way into right field, where he plops down for a much-needed dose of Vitamin D on a sunny, summer Bay Area day. It’s a welcome chance for a good stretch and fresh air following a cross-country flight from Washington.

It also provides a little bit of quiet time, all to himself, before the structured baseball activity of warmups and batting practice begins.

For nearly a decade, the Norristown native has counted on this time before each game to connect his mind and body. And on this occasion, Walker even made a barehanded catch while sitting with his legs out, somehow corralling a two-hopper from Nick Ahmed during the Arizona Diamondbacks’ early hitting — a first for Walker utilizing his Gold Glove defensive skills since beginning his routine of “grounding.”

Players who participate in barefoot walking say the benefits are wide-ranging: Give the feet opportunity to move without the constraints of shoes to potentially decrease pain and inflammation, lower stress, and help normalize the nervous system for improved sleep and day-to-day function among other potential benefits for the heart, cortisol levels and mental health. No accepted scientific studies confirm grounding improves performance, but the players believe it.

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“The science of grounding is harnessing the earth’s energy,” says Walker, a former standout at Kennedy-Kenrick High.

Some 10 minutes after Walker starts his session, barefooted pitcher Kyle Nelson passes with a quick hello while taking his own pregame walk to feel the grass between his toes. Ahmed does it, too, while Cubs outfielder Mike Tauchman removed his shoes for a walk at Oracle Park during Chicago’s June visit.

San Francisco left-hander Sean Manaea is another big fan and can often be seen skipping or shuffling barefoot from the Giants dugout, his long, dark locks swaying in the breeze.

Walker, 32, is thrilled how the practice has caught on all over as players find it useful for their own reasons.

When he began doing it during his second season in the big leagues with Baltimore in 2015, Walker heard all the teasing, friendly jabs, and scrutiny.

“Everybody’s got some funny joke about grounding or earthing or trying to make a joke about being a hippie, or whatever the funny narrative is,” he said. “It’s cool to see more people doing it.”

Now a nine-year veteran, Arizona’s slugging first baseman arrives early enough to get his work done 10-15 minutes before the home team begins its pregame routine of batting practice and ground balls.

Sometimes it will be just walking a lap around the outfield, or lying in the grass and stretching out his limbs.

“I love the sunlight on me, so I try to wear something sleeveless,” Walker said. “It doesn’t take much. Even if the other team is out here for batting practice, I can usually find a quiet corner somewhere and just kind of be in the moment.”

He started earthing under the guidance of then-Orioles strength coach Trevor Howell — “before there was much info on it.”

“It started as we were working on sprint form and working on ankle mobility and stuff like that,” Walker said, “and it’s kind of evolved into something else for me.”

Manaea almost dances as he moves barefooted through the left field grass and out to the hidden bullpen in center field for a breathing session led by Giants human performance specialist Harvey Martin.

Assistant pitching coach JP Martinez participates, too, and the three men find seats along the outfield wall where they will be safe if a batting-practice ball happens to fly over the fence.

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For 15 minutes, they transform into another world. Inhale-exhale in a constant rhythm, then a lengthy breath hold of 90 seconds. Repeat. It’s focused meditation and breath work.

“The first thing I go to in the foundation is your breathing,” Martin said. “Breathing is kind of the language of the body, the connector of the mind and the body.”

Manaea, who pitched a no-hitter for Oakland five years ago and has handled a variety of roles in his first campaign with the Giants, suddenly found himself needing support last season in San Diego, when he struggled with self-doubt. Eventually, the pitcher asked for help and knew he had to make changes — hardly an easy task for someone who describes himself as a “solitary person.”

Manaea confided his struggles to his girlfriend, teammates, family and friends.

Now, he works regularly on breathing and even focuses his efforts on something simple like being a better friend.

San Francisco’s Joc Pederson also counts on constant support from Martin and is committed to breath work and earthing. He and Manaea have pointed to the important skills they’ve gained from both Martin and Shana Alexander, the Giants’ director of mental health and wellness.

“Realizing that I’m not alone on this journey was very helpful,” Manaea said. “It’s not just me, there’s a team behind me. It took a lot for me to realize that. ... It took me a while to realize there are people in my corner.”

Manaea said he learned from a 2022 season in which he underperformed by his standards: 8-9 with a 4.96 ERA and his fewest innings at 158 pitching a full season since his rookie year of 2016 in Oakland.

“I don’t think I did a really good job at it,” he said, “but I did get through it.”

Arizona’s Ahmed reminds himself “to be grateful for the opportunity that I have to do what I love doing and to do what I’ve wanted to do since I was a little kid.”

For Walker, there’s a peace to keeping baseball in perspective by reminding himself each day to soak in the beauty around him, to notice the small details. Even in the unpredictable conditions of Colorado’s Coors Field, where you might get snow in May.

He looked around at San Francisco’s empty ballpark last month and appreciated all of the elements.

“For me it’s not about a nice day,” Walker said. “What I’m after is just being outside — the fresh air, feeling the grass on my feet, walking around and feeling my toes be able to spread out. It’s more of a decompression I feel like than anything. ...

“It’s just such a nice change of pace, especially at this baseball stadium. This is such a cool thing.”