Coach Bobby Kersee Explains His Logic Behind Athing Mu’s 2025 Racing Schedule

The start to Athing Mu‘s 2025 season has been…bizarre. She started off by lining up for a 5,000-meter race — a distance she had never raced on the track — against a field of collegians at the Mt. SAC Relays on April 18. During that race, she ran the first 7.5 laps as part of a four-woman pack, mostly on the outside of lane 1, before dropping out after passing three kilometers in 9:42.

Mu followed that up on May 11 by racing in a three-person 1500 at the Very, Very Last Chance meet — a Division II meet hosted by Cal State LA — where she ran 4:21.18 to win by 55 seconds. Most recently, she ran 4:10.70 to finish 2nd in the third heat of the 1500 at the Sound Running Track Fest at Occidental College on May 24.

It is not uncommon for professional runners to start their season by racing an off distance at a low-key meet. It is uncommon for an athlete to run a race two events removed from their primary distance (800 runners rarely run 5,000s, or even 3,000s). And to race at an event as uncompetitive as the Very, Very Last Chance meet, where the runner-up’s time of 5:16.98 wouldn’t come close to winning most high school invitationals. And to run three such low-key races before testing oneself in a major event. Particularly when the athlete in question is an Olympic champion, world champion, and American record holder at 800 meters.

Mu, shown here racing the 5,000 at Mt. SAC, has made an unorthodox start to her 2025 season

But Mu’s coach Bobby Kersee has always done things the Bobby Kersee way, and at 71 years old, he is not particularly concerned with what anyone else thinks. In interviews so far this year, Mu has provided little explanation for the design of her 2025 race schedule, but Kersee was willing to explain it in an interview with LetsRun.com last week. Kersee, a diehard Yankees fan, explained that the aim of those first three meets was to get Mu comfortable racing in a pack again and give her an opportunity to enjoy the sport before returning to “the majors.”

“If I was a baseball coach with a pitcher, if I sent them down to the minor leagues to throw a couple of innings to see how their fastball is working and see if their changeup is there and see how their arm feels after 30 pitches or 60 pitches, I wouldn’t be criticized,” Kersee said. “So it’s basically the same thing.”

During Mu’s breakout year of 2021, she was so much better than everyone that she rarely had to think about tactics; she wound up winning the Olympics by leading wire-to-wire and running a world-leading 1:55.21 in the final. But that is a luxury she will not always be able to afford in an event as physical as the 800, the shortest distance not run in lanes. Mu has very long legs, and while they have powered her to amazing achievements on the track, they can become a liability in a tight pack. Ever since her AAU days, Mu has willingly run significant extra distance on the turns while leading, leaving the inside of lane 1 open because she believes she is less likely to be tripped there than by running on the rail.

Despite those efforts, Mu has lost her balance in several of her biggest races as a pro. She was clipped from behind and almost fell in the 2021 Olympic Trials final and the semifinals of the 2023 World Championships. And in the 2024 Olympic Trials final, Mu tried to cut in off the break when there wasn’t enough room and was clipped from behind again; this time, she fell and wound up finishing last.

Kersee admitted that they were hoping for more competition in Mu’s second race of 2025, where four athletes scratched before the start. But he believes it is important for Mu, who turned 23 on June 8, to get used to the experience of racing with others, particularly because she runs workouts alone.

“I’ve gotta put her in positions to be in a group, even if it’s for 200 meters, just to find a lane, check her stride, get into a rhythm or what have you, peek over her shoulder,” Kersee said. “Because she doesn’t have to do that much, if at all, during practice.”

Given Mu did not finish her first race and ran her second race essentially alone, it was hard to take much away from those efforts. But Kersee said he was pleased with how she ran at Track Fest, even though she was run down by Sadie Sargent in the final 100 meters.

“She was right on, because I wanted her to run somewhere around a 4:10 and she did,” Kersee said.

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400? 800? 1500? “I believe all three.”

Mu was 2nd in the 1500 at the 2023 US championships (Kevin Morris photo)

When Mu joined Kersee in the fall of 2022, she had already established herself as the greatest combined 400/800 runner the United States had ever produced. She had set an American record of 1:23.57 to win the US indoor title at 600 meters as a 16-year-old high schooler. She had set collegiate records of 49.57 in the 400 and 1:57.73 in the 800 as a Texas A&M freshman. She had won Olympic and World 800-meter titles before her 21st birthday as a pro. Which is why it came as a huge surprise in 2023 when Mu ran the 1500 meters at the US championships and Kersee began talking about a potential Olympic 800/1500 double in 2024.

Mu exceeded all expectations by finishing 2nd in the 1500 at USAs in 2023, establishing herself as a true unicorn. In the history of the world, 117 women have broken 50 seconds for 400 meters. Only one of them, Caster Semenya, has a pb within 10 seconds of Mu’s 4:03, and Semenya is now barred from the female category because she is XY-DSD. Clearly, Mu can run a good 1500. But her 49.57 personal best — as an 18-year-old college freshman — suggests she has far greater potential in the 400 than the 1500.

I asked Kersee: does he view Mu as a 400/800 runner or an 800/1500 runner?

“I believe all three,” he said. “…Her sweet pitch is the 800, but I think she’s got two other pitches as well.”

He said that, just as his other star, Sydney McLaughlin-Levrone, has run the 100m hurdles to improve her 400m hurdles, he believes racing the 1500 will ultimately help Mu’s 800.

“Aerobically, to run a 1500 meters is going to be as much beneficial as speedwise for Athing to run the 400,” Kersee said.

And while Mu has yet to run a 400 since switching to Kersee, he said that is largely due to bad timing. Kersee said he had planned on having Mu race a pair of 400s at Mt. SAC and Occidental College last spring before she tore her hamstring in the leadup to the Olympic Trials. He said he wants Mu to race the event in future, and he believes she is capable of running under 49 seconds.

“It’s not that I’ve taken the 400 away from her” Kersee said. “It’s just that unfortunately last year, when we were starting to make that move, an injury occurred that prevented her to be able to run the amount of 400s that I wanted her to run.”

One thing that is unlikely to happen anytime soon is for Mu to race McLaughlin-Levrone in a 400. Kersee has never enjoyed having his biggest stars race against each other. At the 1984 Olympics, Kersee could not bear to watch his athletes Valerie Brisco-Hooks and Florence Griffith-Joyner race in the 200m final, so he left the Los Angeles Coliseum rather than try to cheer for both of them. In the spring of 1988, Kersee coached the two best 100m hurdlers in America, Gail Devers and his wife Jackie Joyner-Kersee, but had them run separate schedules as they traded off the American record.

If both are at their best, a 400m matchup between Mu and McLaughlin-Levrone would be one of the races of the year, but Kersee said such a matchup is unlikely to happen outside of a championship.

“For coaching-wise, I’m going to run them separately because I want to be able to look at them individually against other people,” Kersee said. “…The only way I see it happening is either going to be at our national championship or a World Championship or an Olympic Games.”

As for the rest of the 2025 season, Kersee said Mu’s plans are up in the air. He prefers his athletes to race domestically to cut down on travel, but the USATF NYC and LA Grand Prix were cancelled this year. Kersee said they had been considering running the 800/1500 at Grand Slam Track Los Angeles on June 28-29, but that meet was also cancelled. So now he’s not sure whether Mu will race again before the Pre Classic on July 5, where she is scheduled to face Olympic champion Keely Hodgkinson in the 800m.

“I’m talking to her managers to look,” Kersee said. “Hopefully we can. But if not, then we’ve just got to prepare best we can and open up at Prefontaine.”

Looking ahead, the World Championships are in Tokyo in September at the same stadium in which Mu won her Olympic title (sans fans). But to make it there, Mu must first qualify at the USATF Outdoor Championships from July 31 – August 3 at Hayward Field. Mu will be running at USAs, but Kersee declined to say in which event.

“I’m not sure yet,” Kersee said. “You can ask me that question in a month.”