22/05/2026
"(...) durability deserves more attention than fresh-leg performance" and "the race is decided by what's left, not by what was there at the start". Yet an interesting read ⬇️ that highlights the importance of doing hard work at the end of your training runs, on tired legs, and not always when you´re well rested and with your eyes set on Strava stats. Accumulated fatigue, how we manage it, and how it impacts our performance, both physically and mentally, is crucial in ultra running. Regardless of s*x. A very interesting topic and hopefully more research will follow 🙏
Most of us measure fitness by what we can do when we're fresh. VO2 max, threshold pace, a fast 5K when the legs feel good. But racing rarely asks that question. Racing asks what's still available after two or three hours of accumulated fatigue, and a new study suggests that on that specific measure, men and women hold up very differently. Researchers compared 11 highly trained female trail runners with 11 highly trained males, matched by performance level using International Trail Running Association rankings, and put both groups through a 3-hour treadmill protocol with a 12-minute uphill time trial inserted every 60 minutes. The women held up dramatically better, slowing by just 1.1% in the final uphill effort while the men slowed by 9.9%.
The reason wasn't effort. Heart rate, perceived exertion, and peak oxygen uptake during the time trials were broadly similar between the s*xes. What separated the two groups was metabolic and neuromuscular resilience. By the three-hour mark, carbohydrate oxidation had dropped by 29% in the men compared to just 9% in the women, meaning the male runners were leaning much harder on fat metabolism as the run wore on. Peak blood lactate, a marker of how much high-intensity carbohydrate-driven energy was still on tap, fell by 53% in men compared to 27% in women, suggesting the men were losing the ability to access that top metabolic gear when fatigue accumulated. Muscle strength followed the same pattern, with male runners losing 18% of their thigh and knee strength after two hours while the women were essentially unchanged.
Worth noting is one big caveat. Because runners were matched by time rather than distance, the men covered more ground during the protocol, around 26 miles to the women's 22, and burned more energy per kilo of body weight. The researchers tried to control for that statistically and the findings still largely held, but a distance-matched version of the study could close some of the gap. The bigger takeaway for everyday runners is that durability deserves more attention than fresh-leg performance. The athlete with the eye-catching threshold test isn't always the one who delivers at hour three, and one of the more honest ways to assess your own resilience is to slot a short controlled hard effort into the back end of a long run and see how much form, pace, and perceived effort actually deteriorate. The race is decided by what's left, not by what was there at the start.
