Muscle Fiber Composition and Enzyme Activities in Elite Female Distance Runners*

Abstract

This study has attempted to describe the fiber composition and respiratory potential in the leg (gastrocnemius) muscle of highly trained, elite female distance runners. As noted, many of these women were competing successfully in middle-distance (1500-3000 m) rather than long distance (10 km and marathon) events. This fact appears to explain many of the differences observed between these "elite female runners" and the "elite male runners" studied in the 1975 Dallas study (6). With the exception of differences in muscle fiber areas, the female runners appear to show the same enzyme adaptations to endurance training that have been reported for male runners. The most notable finding of this study was the remarkable similarity of muscle fiber composition and enzyme activity for male and female runners when matched according to their preferred competitive distance.