I am always looking for interesting research papers to read and came across this one at the end of last week. It is a case study published ahead of print in the Journal of Exercise Science & Fitness.
It gives us a data filled glimpse at how a female athlete was the last one standing, man or woman, at a Triple Deca Ultra Triathlon event.
This is the first case study to look into pacing in a multi-day triathlon longer than 10 days, let alone the first case study featuring a woman competing in such an event.
What the heck is a Triple Deca Ultra Triathlon?
Let’s start with the basics. A Triple Deca Ultra Triathlon is 30 full Ironman-distance triathlons, completed daily. The total distance is114 km of swimming, 5,400 km of cycling, and 1,265 km of running. This event took place in Desenzano del Garda, Italy (Sept/Oct 2024).
I personally think that is as crazy as it is impressive.
Seven athletes started - 6 men and 1 woman. The first man dropped out on Day 1 and the last man dropped out on Day 16, so our female athlete was racing solo for 13 days and finished the race as the only woman to ever do so. She averaged just over 16 hours per day.
The Athlete
This was obviously not her first ultra-endurance event. Our athlete is a 53-year-old Austrian ultra-endurance athlete (164 cm, 67 kg).
In ultra-cycling, she finished the Race Across America (RAAM) 2nd woman in 2017 and 3rd in 2019. In 2019, she set a world record in the Race Across Australia (3,966 km) and two world records with 13,333 km in 30 days and 3,953 km in one week.
In ultra-triathlon, she set a world record in 2016 in the Double Deca one-per-day, in 2018 in the Quintuple one-per-day, in 2022 in the Deca one-per-day, and in 2023 in the Double Deca continuous race (554:56:32 h:min:s 🤯).
She has been competing in ultra-endurance events for over two decades, training 20-30 hours per week on average.
The Data
The researchers used data from the official race website and physiological recordings - average heart rate, maximum heart rate, and energy expenditure from a Garmin Fenix 7 Sapphire Solar. They looked at lap and split times for swim, bike, and run across all 30 days, cross-referenced with daily heart rate and energy expenditure.
Key takeaways
- A very even overall pacing strategy throughout the 30 days, with a daily time variation of just 2.9%.
- There were differences across disciplines. Swimming speed stayed stable throughout the month, cycling slowed down the most, while running got faster in the last 10 days, as a deliberate trade-off in service of overall consistency and record-breaking completion.
- Cycling was the strongest predictor of overall race time, and swimming had very little significance on total time.
Side note - While the authors note this is consistent with Ironman-distance events, I beg to differ based on where the sport has been trending for well over a decade now, with more athletes coming from draft-legal backgrounds with very strong swimming foundations, but that’s beside the point for an event like this
- Heart rate and energy expenditure, perhaps predictably, differed across disciplines and were closely tied to cycling performance. For running, HR alone explained 45% of performance variation, making it the best indicator of how she would perform on the run each day. This is a clear example of how fatigue accumulates differently across disciplines.
Given this was a case study, there are no definitive conclusions as to why a woman reached the finish line when the men did not.
What is clear is that race experience matters here, a lot. You need to build toward something like this, and experience in similar events matters more than fitness alone. This woman had more experience in ultra-distance events than anyone else on that start line and it clearly showed.
It is not new knowledge that women tend to have a higher percentage of slow-twitch (Type I) muscle fibers and greater resistance to fatigue over very long efforts, but it keeps getting highlighted in ultra-endurance events. The longer the event, the smaller the gap tends to be between women and men, where the dominant factors for success become pacing strategy, fat metabolism, and fatigue resistance.
In Practice
The practical takeaways are not necessarily new, but they deserve highlighting.
Pacing on the bike matters, because it directly affects the run. Triathlon is not merely the sum of its parts (swim–bike–run), it is a sport of its own, regardless of distance. The data from this event illustrates that nicely and shows how that understanding shaped decision-making throughout the race.
HR is still a valid tool, many decades later. We have so much technology now and many athletes have leaned heavily into power and pace data, but tried and tested heart rate data remains an important predictor and self-regulation tool for both cycling and running performance, even across 30 consecutive days of racing.
Women are underrepresented in sport science research, so case studies like this one matter for athletes, researchers, and practitioners alike. Visibility is important. Yes, there are limitations given the sample size of one, but this study provides meaningful data on how women perform in events longer than 10 days. There aren’t many people, men or women, competing at events of that length, so every piece of literature added to the body of knowledge counts.
Finally, the fact that only one woman out of seven toed the start line, and that she raced solo for two weeks, is worth acknowledging. She was alone, without anyone to pace off of and without the camaraderie of other competitors on course. That is tough. You need to be incredibly disciplined, driven, and mentally resilient to do that. No doubt she knew she was on the verge of something historic, which must have been deeply motivating, and she clearly had the patience and physiological conditioning to make it happen.
Overall, this was an interesting and inspiring read, which is why I chose to share it here. If you want to read the full paper, it is available below (full text). Comments? Questions? Use the space below ⤵️
Reference
Duric et al. (2026). Pacing of the first and only female finisher in the world’s longest triathlon: The 2024 Triple Deca ultra triathlon. Journal of Exercise Science & Fitness, 24, 200454
