Therese Johaug, from cross-country skiing legend to marathon debutante with her sights set on Los Angeles 2028

There are athletes who retire. And there are athletes who simply change their obsession. Therese Johaug, the Norwegian who dominated cross-country skiing with four Olympic golds and a résumé of world titles that unnerves any rival, is going to run her first marathon in Valencia. She's not doing it as a farewell or as a whim of a bored ex-elite: she's doing it with her sights set on Los Angeles 2028, when she will be 40 years old. And her debut marks—30:51 in 10K and 1:08:43 in the half marathon—are not those of someone who is "trying out" running. They are those of someone who already competes on equal footing with the best distance runners on the planet.

This story matters because it challenges an entrenched idea: that running's elite is formed from adolescence running kilometers and kilometers on asphalt. Johaug built her aerobic engine over two decades of cross-country skiing, one of the most demanding disciplines that exists in terms of cardiovascular capacity. Now she is transferring that engine to a new discipline. And the entire sport is watching to see how far she can go.

The context

Cross-country skiing and the marathon share more than appears: both are tests of extreme endurance where the winner is whoever best manages their energy during more than an hour (or several) of sustained effort. What changes is the technical movement, the joint impact, and training specificity. Johaug doesn't start from scratch physiologically—her VO2max and her capacity to sustain high paces for long periods are world-class—but she does face a real technical and biomechanical learning curve: running punishes the body in a way skiing does not, with thousands of repetitive impacts that demand specific adaptation of bones, tendons, and musculature.

Her career also carries a shadow: in 2016 she was sanctioned for doping (a case linked to a lip balm containing a prohibited substance) and served 18 months out of competition, an episode that shook Norwegian sports and which she has always defended as an involuntary error. She returned, won more medals, and today takes on this new chapter under an even more intense public spotlight.

The stated objective—Los Angeles 2028—makes sense in a context where women's marathon has experienced an explosion of level in recent years, with times that a decade ago seemed like science fiction. Johaug is not here to finish: she is here to compete.

What the science says

The transition from a low-impact sport like cross-country skiing to running is not trivial. Evidence on bone stress injuries in distance runners shows that bone needs time and progressive loading to adapt to the repetitive impact of asphalt, something Johaug never had to manage on skis (Warden et al., 2014; George et al., 2024). It is probably the biggest hidden risk of her project: not aerobic capacity, but the capacity of the locomotor system to tolerate thousands of impacts per session.

On the other hand, her background in extreme endurance gives her an advantage that science strongly supports: strength training and the aerobic base built over years improve the "durability" of running economy, that is, the capacity to maintain efficient technique even in advanced fatigue, something critical in the final 10 kilometers of a marathon (Zanini et al., 2025). Johaug arrives with that capital already built, only forged in another discipline.

There is also evidence of clear differences between female and male pacing in the marathon: women typically show a more stable rhythm distribution and less prone to final collapse, a well-documented physiological-behavioral pattern (Nikolaidis et al., 2019; Besson et al., 2022). For a debutante like her, understanding and executing that pacing strategy well will be as important as her physical foundation.

What it means for you

You don't need to be an Olympic champion to learn from this. The central message is that aerobic base is transferable, but impact doesn't forgive shortcuts. If you come from another endurance sport (cycling, triathlon, rowing) and switch to running, respect a much more conservative loading progression than your cardiovascular condition suggests: your lungs will be ready before your bones and tendons.

Incorporate strength work from day one, not as a complement but as a pillar: it improves running economy and protects you in the final kilometers, when technique breaks down the most. And if you're planning a marathon, practice your pacing strategy in long workouts before race day: the difference between a good marathon and a disaster is almost always decided by how you distributed your effort, not how much you trained.

Johaug has five years ahead of her to perfect that puzzle. It's worth following the experiment.

References

• Warden SJ, Davis IS, Fredericson M. "Management and prevention of bone stress injuries in long-distance runners." J Orthop Sports Phys Ther, 2014. https://pubmed.ncbi.nlm.nih.gov/25103133/
• George ERM, Sheerin KR, Reid D. "Criteria and Guidelines for Returning to Running Following a Tibial Bone Stress Injury: A Scoping Review." Sports Med, 2024. https://pubmed.ncbi.nlm.nih.gov/39141251/
• Zanini M, Folland JP, Wu H. "Strength Training Improves Running Economy Durability and Fatigued High-Intensity Performance in Well-Trained Male Runners." Med Sci Sports Exerc, 2025. https://