Singapore ultra runner completes a personal marathon grand slam with Kyoto Marathon, Osaka Marathon and Tokyo Marathon added to the list, each just a week apart from the other
We are less than three months into 2025, but Singaporean Ultra runner Sebastian Cheong has already accomplished a remarkable feat in endurance - completing three major Japanese marathons in just three weeks.
Dubbed a personal “Marathon Grand Slam”, the Superhero Runners co-founder successfully crossed the finish lines of the Kyoto Marathon, Osaka Marathon, and Tokyo Marathon, pushing both his physical and mental limits in this extraordinary challenge.
The Journey of a Lifetime
Completing a single marathon is a daunting task for many, but running three in rapid succession is a challenge few would dare to undertake. For Cheong, it was a test of endurance, resilience, and sheer willpower.
“It’s a mix of exhaustion and pure fulfillment,” he shared after finishing his final race in Tokyo, his first World Marathon Major despite having completed well over a decade of marathons and a few ultra marathons to date.
“Running three marathons in three weeks was physically and mentally demanding, but crossing that final finish line made it all worth it. Tired? Definitely. But the sense of accomplishment is unbeatable!”
The Birth of a Bold Idea
The concept of running three consecutive marathons didn’t arise overnight. It stemmed from a desire to push beyond conventional marathon limits.
“This idea first came to mind when I started looking for a new challenge beyond just a single marathon,” Cheong revealed. “The thought of pushing my limits with three marathons in three weeks seemed both crazy and exciting, so I knew I had to go for it!”
Overcoming Adversity
While the feat was ambitious, Cheong faced significant hurdles along the way.
“The biggest challenge was definitely going into these races with an injury and a lack of training in the last four weeks,” he admitted. “Mentally, it was tough knowing I wasn’t in peak condition, but I focused on listening to my body, pacing smartly, and trusting the endurance I had built over time. It wasn’t easy, but pushing through and finishing all three marathons made it even more rewarding!”
A Surprise Personal Best
Despite the fatigue of running back-to-back marathons, Cheong achieved an unexpected personal best (PB) in the Osaka Marathon, completing the 42.195km in 3 hours 18 minutes, lowering his previous personal best set at the 2024 TCS Sydney Marathon by 2 minutes.
“It wasn’t planned at all!” he said. “The original plan was to treat Osaka as a recovery run before the final marathon. But halfway through, I realized the course was pretty flat and felt surprisingly good, so I decided to pick up the pace and go for a PB. Glad I took the chance!”
The Magic of Japan
Beyond the rigorous racing schedule, the experience was deeply enriched by Japan’s electric race-day atmosphere.
“My favorite memory from Japan has to be the incredible vibes,” Cheong recalled fondly. “The energy from both the runners and supporters was just unreal. Every race felt like a celebration, with spectators cheering nonstop and fellow runners pushing each other forward. It made the whole experience so much more special!”
What’s Next?
After such a monumental effort, Cheong is now taking a well-deserved break before deciding on his next major challenge.
“For now, I don’t have any big plans yet. I’m taking a break to recover before deciding what’s next,” he said. “In the meantime, I’ll be racing in some local events and focusing on shorter distances, like the 2XU Run and Singapore T100 Duathlon Relay, to keep things fun and fresh!”
Advice for Aspiring Runners
As an accomplished endurance athlete, Cheong has words of wisdom for those looking to take on similar challenges.
“I definitely wouldn’t recommend doing three marathons in three weeks!” he laughed. “Endurance running is all about patience and consistency, so take each marathon journey with respect, train smart, listen to your body, and enjoy the process. The progress will come with time!”
Sebastian Cheong’s Marathon Treble is a testament to the power of determination, adaptability, and passion for the sport. His journey inspires runners worldwide to push their boundaries while also emphasizing the importance of strategic training and recovery. Whether he embarks on another ambitious endurance feat or takes a step back to enjoy the running community, one thing is clear—his story is far from over.
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