Segmented linear regression provides a nice tool for looking at performance of male and female skiers as they age.
Male and female classic skiers have similar performance patterns except that male finish times can be best modeled with four linear phases while female performance is best modeled by three.
The initial slow-down from age 18-33 for both genders is a different pattern from that seen in the top 5 classic and freestyle graphs. It’s not clear why this is the case, but it may be an artifact. The proportion of young and fast classic skiers has increased over the years. The percentage of classic skiers from 18 to 33 has increased from 13% in 1999 to 28% in 2025. In recent times, the younger skiers may be more focused on their training than those in the early years when classic was not as popular, and they have been skiing on a faster, less degraded track since 2008 when the separate classic trail was established.
In the youngest phase, males aged 18 to 33, slow down by about 3:08 min:sec/yr, and females aged 18 to 33, slow down by 1:50 min:sec/yr. After the first transition, the performance of skiers of both genders levels out a bit – males slow by 29 sec/yr to age 56 and females by 15 sec/yr to age 60.
Males transition to the final phase at a later age than females – 71 versus 60.
(More on statistical significance for estimates of breakpoints and slopes.)
Note: Finish times are standardized to a 55k classical race or a 50k freestyle race.