365 Days, 365 Triathlons, and a Record-Setting Experiment — Triathlete

Jakko Sahimaa may be the only four-time world-record-holding triathlete you’ve never heard of.

He’s not the fastest. Not even close. But he may be one of the most prolific – or at least the busiest. In 2025, Sahimaa, who is from Finland, completed 365 super-sprint triathlons in 365 days, setting a world record.

Along the way, he set additional records for the most super-sprint triathlons completed in a week and in a month. Then, last October, he pushed further, completing 54 super-sprint triathlon legs in 24 hours – the most ever recorded, according to Guinness World Records.

Present a list of feats like this to anyone who understands what it takes to swim, bike, and run nearly every day, and their first question may be, “Why?” For Sahimaa, a longtime triathlete, the answer began with his bathroom scale.

How the idea started

“It all started when I noticed that I was a little bit overweight. Like half a year before the project, I weighed myself and I was 99.9 kilograms [220 pounds], which was quite a shock for me,” the 32-year-old recalls. “And that was the starting point. … [I thought,] ‘Well, I’ll change my workout routines. I’ll do half an hour per day [of exercise] for like half a year.’ And then during that time I got the idea.”

Turns out, Sahimaa is full of ideas. As a psychologist focused on work-life balance and sustainable performance in Finnish society, he has built his career around year-long “explorations.”

He once spent 12 months working in 12 different jobs to study the meaningfulness of different roles. The triathlon project followed that same framework: Take a clear hypothesis and test it through disciplined, daily action.

The hypothesis this time? That consistent physical activity strengthens self-esteem, reinforces self-efficacy, and, on a personal level, brings identity back into alignment. Sahimaa had long seen himself as an athlete, but in recent years – especially with the addition of toddler twins and an infant to his family – his habits hadn’t matched that self-image.

“The gap between my identity and my actions was a little bit too big,” he says. The daily triathlons, he hoped, would become a way to narrow that margin.

Overcoming challenges

The structure was simple: He’d finish a super-sprint triathlon (400-meter swim, 10K bike, and a 2.5K run) every day. He built practical systems to make it possible, like a countercurrent pool at home, indoor setups for cycling and running, and Garmin data for verification.

For accountability, Sahimaa posted his daily triathlons on Instagram, pledging one euro per social media follower to Finnish mental health organizations.

But the experiment nearly unraveled before it truly began. Four days in, Sahimaa developed a hand infection that required surgery and forced 20 days off – breaking the consecutive streak almost immediately. For much of the year, he was behind schedule, chasing missed sessions and stacking triathlons to catch up, all while navigating Finland’s long, cold seasons, pop-up injuries, and dips in motivation.

Still, Sahimaa stayed the course.

“I didn’t think even once that I should end this project,” he says. “Those were the most stressful moments – when I was behind my weekly schedule and dealing with pain. But I had the plan that I had to do it.”

There were flare-ups of plantar fasciitis. The 24-hour record attempt in October, coinciding with International Mental Health Day, which, while successful, was physically exhausting. Frequent work trips required him to scout swimming pools across Finland just to stay on track. Not to mention the logistics of arranging schedules with his wife to support a lofty goal that left little room for error.

“Even though I did the triathlons, it was a big project for us,” he shares, adding that while balancing work and family was tough, the workouts made him a better husband and dad.

“That was a big finding for me. When I start my day with exercise, it already sets me up for the day,” he says. “My most positive emotions throughout the year were linked to exercise. It really shows the importance of having meaningful goals.”

Rediscovering a sense of self

Sahimaa completed his 365th triathlon on Dec. 22, 2025, in 36 minutes, 48 seconds – his fastest time yet. “I’m so fed up with triathlons,” he mused on an Instagram reel moments after finishing.

But the satisfaction was real. Along the way, his Tri4Lyfe social media account reached some 13 million views globally, he was featured on Finnish TV and radio, and he, perhaps most importantly, rediscovered his sense of self, confirming his hypothesis at the onset of his “triathlon project.”

Including his fundraising pledges, Sahimaa sank some 20,000 euros of his own money into the experiment to cover equipment and media production for a forthcoming documentary. But he says every euro and every meter of exercise logged – 90.7 miles swimming, 2,268 miles cycling, and 567 miles running, to be exact – was worth it.

“I’m relieved it’s over but glad I did it,” he says. “I learned a lot. And now, I’m in the best shape of my life.”