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Before every pitch, Bobby Witt Jr. repeats the same routine. He steps out of the batter’s box, grips his bat, looks at it and takes a big deep breath.

Witt is the 25-year-old star shortstop of the Kansas City Royals and one of the most exciting players in baseball. As a Kansas Citian, I’ve watched Witt perform this routine hundreds of times, but only recently did I think to ask this question:

What’s the benefit of a single deep breath? The answer surprised me.

Witt developed his routine when he was a freshman at Colleyville High School in Texas.

Brian Cain, a mental performance coach, helped him develop the steps he still uses to this day: find a focal point on his bat, take a deep breath, say something positive.

But the power of that single deep breath clicked for Witt in 2018.

That summer, Witt participated in a high school home run derby. The event was held at National Park, home of MLB’s Washington Nationals, and featured some of the best young hitters in the country.

Witt was certainly one of them. The son of a major-league pitcher, Witt possessed a rare combination of speed, power and athleticism that already had him pegged as a future top pick. But that night, he was just a nervous 18-year-old.

There were 40,000 people inside the stadium, including baseball’s biggest stars: Aaron Judge, Mike Trout, Bryce Harper. Witt could feel their eyes on him as he walked up to the plate. His legs felt as if they “were going to fall out beneath me,” he said on Cain’s podcast.

And then he took a deep breath.

“Just right there, it cleared my mind,” he said, and completely shifted his thoughts from the pressure of the environment to the familiarity of the task: All right. You’re back here in the box. It’s just like you’re hitting BP in the cage. Here we go.

Witt won the home run derby that night and realized the power of a single breath to change an outcome.

Witt is not alone. LeBron James has done it during timeouts. Scottie Scheffler has done it during big golf tournaments. An NFL player did it on the field in the Super Bowl. Some pro teams use an app to show their players the effect deep breathing has on their heart rate.

As Peak’s Rustin Dodd wrote last year, the science is clear: Regular deep breathing (or breath work) can reduce anxiety, blood pressure and heart rate while improving mental health. Researchers have also found that a single five-minute session of deep, slow breathing can be beneficial.

But what about a single deep breath?

Sylvain Laborde can trace his initial interest in breathwork back to his asthma, which forced him to drop out of sports. Now a professor and researcher at the German Sport University Cologne, Laborde has spent the last two decades trying to understand and explain the power of breathing techniques.

Yes, those techniques could often help people relax, but he realized that was only a part of the benefits. So he and three other experts wrote a book, “Heart Rate Variability: Science and Strategies for Peak Performance,” that explores the different benefits of breathing.

One of their takeaways: Breathing not only impacts our autonomic nervous system, but the kind of breath we take impacts it in different ways.

By measuring heart activity, Laborde and his team found that deep exhalation triggered the parasympathetic nervous system, which acts as the brake pedal in a car. It’s the reason why our heart rate slows and our anxiety reduces when we let out a long breath.

But deep inhalation triggers the sympathetic nervous system, or the gas pedal. Laborde’s team found — and recent neuroscience backed it up — that deep inhalation sharpens our concentration and makes us more alert.

Laborde said there was an easy test people could do at home. Take two fingers and put them on your pulse. Take a really deep, exaggerated inhale. And then take a really deep, exaggerated exhale.

Each time you inhale, you should notice your heart beats faster. And each time you exhale, your heart should beat slower.

That’s what Laborde noticed when I sent him a clip of Witt’s routine: Witt inhales deeply. He doesn’t let out a long, slow exhale like you might expect. He just takes a really sharp inhale, almost like he’s sucking in.

“The inhalation was stronger and longer, which made me think: Perhaps he uses this unconsciously to activate himself and to focus,” Laborde said.

As I watched the Royals the other night, Rex Hudler, the team’s television analyst, brought up Witt’s breathing routine. Hudler played 13 years in the majors, but never quite lived up to his promise as a first-round pick.

As he talked about Witt’s breathing, Hudler said: “I wish I would have learned that when I was a player. It would have helped.”

If you want to read more about Witt’s routine, Elise Devlin tried out parts of it for a week. Her takeaway? Witt has next-level discipline.