Sex Differences in Participation and Performance Trends in Time-Limited Ultramarathon Events.

We aimed to analyze sex differences in time-limited ultramarathon participation, while also identifying trends in participation, age, and performance across different formats of events, from 1990 to 2020. This is an exploratory study, using data obtained from the official event web pages. We downloaded information regarding the year of the event, athletes' year of birth, sex, race event, ranking, and mean running speed (km/h). The sex gap in participation was presented through equiplots. Regression models were fitted to analyze trends in participation, age, and performance, considering a 95% confidence interval. A similar pattern of increase in participation and age was shown for athletes of both sexes until 2019. The sex gap remained, displaying different patterns across race events. A general trend of slower mean running speeds was shown. The random-effects analysis showed that sex and age played significant roles in the performance trajectory across the years, in each race event. Apart from the 8-day race among females, there was a decline in the performance across all race durations. Despite the trend of performance decline, future studies need to address the relevance of this decline in both theoretical and practical terms.