Since he was born in Panama in 1954 to a Panamanian mother and U.S. Navy father, Bobby Kersee has always been restless, a self-described wanderer with energy that matched his athletes. But in 2019, feeling unusually sapped, he called his doctor in St. Louis. Blood tests produced results dangerously far beyond the norm. Pancreatitis kept him stuck in a hospital for four weeks.

Once discharged, Kersee gave up red meat and alcohol.

What he would not quit was track.

Forty years after coaching his first world champion Kersee, now 69, paced relentlessly for four hours on Thursday while watching his training group at West Los Angeles College.

“Everyone kind of says the same thing: You know, he’s different in terms of he’s basically a mad scientist,” said Athing Mu, the 20-year-old reigning Olympic and world champion at 800 meters who switched to Kersee’s coaching in September to expand her range. “He knows what he’s doing.”

Under cloudy skies at the track high above Culver City, nine athletes in his training group, dubbed Formula Kersee, ran tailored workouts and waited for his every word, from the barked “let’s go!” to commands about mechanics he hollered to athletes mid-run. He lifted hurdles, held court with reporters and stopped only to film block starts with his iPhone.

At an age when he might have become anachronistic, Kersee and his methods still represent sprinting’s gold standard, associates and athletes say. Invigorated by a training group that describes itself as a family and could be dominant into the next decade behind headliners Mu and 23-year-old 400-meter hurdles world champion and world record-holder Sydney McLaughlin-Levrone, Kersee said his career has no discernible finish line.

His coaching, primarily of sprinters and hurdlers, has brought his athletes at least one gold medal in 10 consecutive Summer Olympics, a litany of world championships and world records and, for Kersee, veneration, criticism and influence.

As the first professional meet held at UCLA’s Drake Stadium since 1990, and a key early tentpole in USA Track & Field’s attempted plan to grow its U.S. fanbase before the 2028 L.A. Olympics, this weekend’s Los Angeles Grand Prix is both a callback to a time when track’s popularity soared and, its organizers hope, a harbinger such times can return.

Outside of Sebastian Coe, the 1984 Olympic gold medalist in the 1,500 who has since ascended to lead track’s global governing body, World Athletics, few figures have spanned both eras as prominently as Kersee.

Athletes and associates credit his ability to turn seemingly outlandish goals and times into tangible results to an ability to know what they need. Malachi Davis, who has overseen McLaughlin-Levrone’s training since she turned professional, likened Kersee to a conductor, his whistle and yellow stopwatch replacing a baton to direct “a beautiful dance of confidence and knowledge.”

Many coaches can teach how to run fast and build a race plan, McLaughlin-Levrone said, but Kersee understands “how to break it down piece by piece.”

“I’ve never met any coach like him,” said Athing Mu, who said it took her two months into training to understand track guru Bobby Kersee’s training language.

(Allen J. Schaben / Los Angeles Times)

Robert Forster, a Santa Monica-based physical therapist who has worked with Kersee’s athletes since 1983, said Kersee understands the “work-rest ratio” better than any coach, and does not overtrain where other coaches might double down on mileage. Forster has seen Kersee send an athlete home to rest just from the look on their face, and likes to tell a story about the 2016 Olympics, that Kersee later confirmed. Allyson Felix, the Los Angeles native who under Kersee became the most decorated athlete in track’s history, was nursing a severely sprained ankle and the physical therapist told Kersee it needed to be iced 20 minutes every hour. Forster did not expect, however, that Kersee would stay up the entire next night icing the ankle as Felix slept.

Kersee was an early adopter of technology, upgrading his video cameras at a Westwood electronics store years before he could film block starts of sprinters Jenna Prandini and Morolake Akinosun on his iPhone and zip the footage to an iPad on the infield of the West L.A. track.

Yet the Kersee mystique has endured as much because of his grasp on psychology as biomechanics — feeling for when to push and when to pull back.

Brandon Miller, a top 800-meter hopeful who began working with Kersee in September, has heard other athletes describe Kersee as “crazy.” He disputes that characterization, but noted that Kersee knows to stoke his competitiveness entering a workout’s final repetition with four words: “OK, what you got?”

“I’ve never met any coach like him,” Mu said. “He’s not going to make you do anything that’s for his sake. You know, it’s gonna be all for you and the benefit of you and your career. And so, I come in here, I knew that he was very intentional, and that’s something I needed, especially if I want my career to be long.”

Raised by a grandmother as an “A-train baby” bouncing between the Bronx and Queens, Kersee lost his mother, Daphne, when he was 14, before moving to San Pedro for high school.

He put himself through college at Long Beach State by working at a youth correctional facility in Whittier, where Kersee watched wards from midnight until 8 a.m. After graduating, he had two jobs: Track coach at Cal State Northridge, and counselor at another youth facility in Chino. He took over UCLA’s track and field program in 1980 and that provided enough money to be comfortable. Coaching Greg Foster to his first world championship in 1983, and watching his athletes win six golds and four silvers at the Los Angeles Olympics one year later, provided the final confidence he could sustain coaching as a career.

Bobby Kersee lifts Florence Griffith Joyner after her win in the women’s 100 meters at the U.S. Olympic trials in Indianapolis on July 17, 1988.

(Tom Strickland / Associated Press)

But he did not leave behind the edge required to do his former jobs.

“I used to work in the prisons, so you can’t walk into the prisons being Mother Teresa,” he said. “And then I did find myself carrying a little bit too much of that to the track. I had to calm myself down and say, ‘Wait a minute, you’re not working with a warden.’”

Once, an elderly woman approached Kersee in an airport in Indiana and told him she did not like what she had seen from Kersee or the other famed coach with the B.K. initials: Bobby Knight. He did not belittle his athletes, he said, but he also didn’t leave room for interpretation about who ran the workout. The edge created a mystique that “he’s crazy,” Miller said. “But he’s not. I feel like everybody has preconceptions of everybody but you won’t really know unless you’re there and you’re with them every day.”

Just as when he built his vaunted World Class Athletic Club in the 1980s, he will only train those he can coach hard and have chemistry. His athletes typically train Monday, Tuesday, Thursday and Friday. He treats Monday Zoom calls with the group as though he is re-interviewing for the job. It’s more convenient than years before, he said, when he recalled gathering before dawn in Europe to address their complaints with him.

“I think we have that understanding that I’m going to listen and respect them,” he said. “But my job is to get the job done for them individually and collectively but you hired me. And if you hired me, let me do my job.”

That job, essentially, can be reduced to one thing: Imparting confidence in his plan. And no one does it like Kersee, said Davis, who sprinted professionally before aiding McLaughlin-Levrone.

“He’s a competition coach, so the time it counts, you feel confident,” Davis said. “And your head coach is basically your general and then competition is basically war. And yes, you prepare for war but that final voice, that presence, that action, that essence, that’s Bobby. And he earned that by what he’s accomplished throughout his career.”

Kersee allows that age has softened him. As McLaughlin-Levrone recalled last August, Kersee earned her trust when he saw her overwhelmed with emotion at a 2020 practice and handed her a paper showing a wheel of emotions, saying he had trouble expressing himself, too. Used to criticism himself, he worries about how the inundation of social media affects athletes’ mental health. He has traveled to support the singing ambitions of Formula Kersee sprinter Chloe Abbott. This spring, a smiling Kersee was featured on TikTok when his athletes remade the opening credits of the 1990s sitcom “Family Matters.”

Four decades into his career, he has “a whole lot of knowledge and a whole lot of patience,” he said. “But still, don’t let grandpa get out of the chair.”

Ato Boldon was never coached by Kersee during his sprinting career but has known him for 31 years, since they overlapped at UCLA, and has seen a “golden-hearted” side to the coach. He also described Kersee’s coaching equivalent as either Knight or San Antonio’s Gregg Popovich.

“Everybody under him wins,” said Boldon. “But it’s not necessarily a democracy.

“… As time has gone on, people are like, ‘Wow he’s so this or he’s so that, he’s so abrasive.’ Listen, do you want results, or do you not want results?”

No one argues that Kersee gets results. The most common criticism is how rarely his athletes compete en route to smashing records and claiming gold.

Among athletes, meet directors, agents and track officials who see a need for the sport’s biggest stars and strong competition to draw in casual fans, it has become a question of how to unite what is best for the top athletes’ futures with what is best for the sport’s growth. The tensions surrounding the discussion are not dissimilar from the way “load management” in the NBA has sparked concerns whether it will turn off fans from the regular season.

Because many top athletes train under Kersee, he has become a focal point. There is also his history of pulling athletes late before a meet, sometimes because of injury, and sometimes as a power play, as in 1994, when a dispute over pay led him to withdraw Gail Devers from a high-profile Los Angeles indoor meet.

The topic reignited last week when he withdrew Mu and McLaughlin-Levrone from the Grand Prix, a meet for which he serves as co-promoter. It came soon after telling Track & Field News in February that even he would like to see McLaughlin-Levrone run more often, and told The Times in March that there was no reason meets in the U.S. couldn’t draw thousands if the sport’s leaders banded together to promote strong competitions.

Asked about the balance of what is best for his athletes, or the sport, Kersee this week called it a byproduct of limited sponsorship money within the sport, which incentivizes performances at the biggest meets, which often require qualification earlier in the season. Only a handful of stars make big money and can afford to be choosy. He contrasted it with the NFL and NBA, where athletes can still earn a paycheck while resting.

“I think it’s a little tougher on our athletes to try to balance out wanting to run for the public and run for our sport and also knowing if I run too much or make one little mistake it might cost me making a team,” Kersee said. “That if I go out there and run five or six races I’m going to get to the point of, ‘OK why is he running me so much and she gets injured over there, did she really need to run?’”

Sydney McLaughlin-Levrone wins gold in the women’s 400-meter hurdles at the 2022 world track and field championships in Eugene, Ore.

(Ashley Landis / Associated Press)

McLaughlin-Levrone released a statement after being pulled from the Grand Prix field that she “regrettably” would not be competing, citing her coach’s choice. It also said she trusted his judgment, which the world record-holder echoed again Thursday.

“He has a plan and he is going to work it out to perfection,” said Boldon, who will call Saturday’s meet as part of NBC’s broadcast team. “It might not benefit USATF, it might not benefit the fans, but you tell me, what moment stood out most from last summer’s world championships?”

It was McLaughlin-Levrone’s stunning 50.68 time to win the 400-meter world title and lower her own world record. The run cut through the noise to make SportsCenter. It also left McLaughlin-Levrone sore for days, she said. Seeing her parents in the stands, for the first time after becoming the first woman to run under 51 seconds, she told them “that hurt, so bad.”

“We’ve been very calculated in when we run and I think it’s yielded us great results,” McLaughlin-Levrone said. “Bobby always uses analogies and he’s like, ‘You don’t take the Ferrari out every day for a drive. You take it out when it needs to come out and it does its things and you put it back in the garage.’ So, your body can only be pushed to a certain level so much in your career.

“You only have so many races in your legs and I think we’re really strategic about which ones we choose to run. Obviously I know the sport wants to see a little bit more and I think we’re trying to figure out how to do that in a safe way that we can still accomplish our goals and give them something to look forward to.”

For McLaughlin-Levrone and Mu, the question is not whether they will make this summer’s world championships in Hungary, or next summer’s Paris Olympics, but which events — possibly plural — they will run.

When Kersee evaluates whether to bring an athlete into his coaching, he also looks for their potential range. He thought he lost his job coaching Felix when he told the 200-meter star during his interview that he would have her run the 400.

At 69, Bobby Kersee has showed no signs of slowing down. “I have that Energizer bunny still in me,” he says.

(Allen J. Schaben / Los Angeles Times)

Mu and McLaughlin-Levrone’s youth and potential range is one of the sport’s most speculative discussions; news about their upcoming races create instant headlines. The duo are “two of maybe the most talented athletes he’s ever had,” Boldon said.

Their world championships last summer gave McLaughlin-Levrone an automatic berth into the upcoming world 400-hurdle field, and Mu an entry into the 800. With that secured, Kersee has focused on running McLaughlin-Levrone in the open 400 meters, where Marita Koch’s world record of 47.60 has been effectively unapproachable for 38 years — only four women have run even faster than 49 seconds in the past 20 years. She once thought 47.60 was “impossible.” Not anymore.

“It’s a very daunting number to look at, I’ll tell you that,” McLaughlin-Levrone said. “But at the end of the day, I think if we can take the 400 hurdles to 50.6, I think 47.6 isn’t too far off.”

In addition to her 800-meter world title, Mu once owned the collegiate 400-meter record and ran on the U.S. 4×400-meter relay team that won Olympic gold in Tokyo.

“I’m still super young and I have not touched the surface of a lot of things yet,” Mu said. “But I do have visions, which is like really big goals of competing in obviously the Olympics again, and then worlds and hopefully, doubling up.”

Would that mean the 800 and 400, or the 800 and 1,500?

“Hopefully both,” she said. “I mean, I would love to have a chance to do 4/8 and then go ahead and do the 8/15 at some point.”

Maybe this explains why Kersee moved so quickly across the track during practice. There was no sign he had once slowed down.

“I’m glad,” he said, “I have that Energizer Bunny still in me.”