Performance trends in 161-km ultramarathons.

This report documents performance-related trends in 100-mile (161-km) ultramarathon running competitions in North America. A retrospective analysis of results from 1977 through 2008 revealed that annual finish rates increased initially and then plateaued by the early 1990s at nearly 60%. The fastest times were produced by the 30-39 year age group among the men and the 40-49 year age group for the women. Finish times of women improved relative to men through the 1980s, but were then stable over the past two decades with the fastest women running about 20% slower than the fastest men. Additionally, the average times of the fastest runners did not change over the past two decades for any age group for either sex. The percentage difference in finish times between the first and fifth place runners has remained lower (p<0.0001) for men than women, and has shown an upward trend (p=0.003) across time for men. It is concluded that increasing participation in 161-km ultramarathons in North America has not been associated with improvements in performance or depth of competition with the exception of the relative improvements in finish times for women compared with men that was evident through the 1980s. Georg Thieme Verlag KG Stuttgart, New York.