Sex Differences in the Speed–Duration Relationship of Elite Runners across the Lifespan.

Purpose: To determine if the speed–duration relationship is altered with age and sex of elite Master's runners. Methods: The world's top 10 performances for men and women in three events (800, 1500, and 5000 m) across six age groups (18–34 yr, 40–49 yr, 50–59 yr, 60–69 yr, 70–79 yr, and 80–89 yr) were analyzed from public data to establish theoretical models of the speed–duration relationship. Critical speed (CS) and the curvature constant (D ′) were estimated by fitting the average speeds and performance times with a two-parameter hyperbolic model. Results: Critical speed expressed relative to the 18- to 34-yr-olds, declined with age (92.2% [40–49] to 55.2% [80–89]; P < 0.001), and absolute CS was higher in men than women within each age group (P < 0.001). The percent difference in CS between the men and women progressively increased across age groups (10.8% [18–34] to 15.5% [80–89]). D ′ was lower in women than men in the 60–69 yr, 70–79 yr, and 80–89 yr age groups (P < 0.001), but did not differ in the 18–34 yr, 40–49 yr, or 50–59 yr age groups. Conclusions: Critical speed progressively decreased with age, likely due to age-related decrements in several physiological systems that cause reduced aerobic capacity. The mechanism for the larger sex difference in CS in the older age groups is unknown but may indicate physiological differences that occur with aging and/or historical sociological factors that have reduced participation opportunities of older female runners resulting in a more limited talent pool. [ABSTRACT FROM AUTHOR]