# Sex-specific characteristics of special endurance and performance potential in female runners

## TL;DR

This study examines how female runners' endurance and performance change with race distance, revealing sex-specific patterns linked to muscle physiology.

## Contribution

The study provides new sex-specific KsA reference values for female runners across multiple distances.

## Key findings

- Female runners show a more pronounced pace decrease from 100 m to 1500 m compared to males.
- KsA values have remained stable for over four decades in national-level female runners.
- Sex differences in KsA align with known variations in muscle fiber composition between males and females.

## Abstract

The coefficient of special endurance (KsA) is a metric that quantifies the relative pace loss between two consecutive distances (e.g., 100 m/200m). Here, we analyzed over 20,000 race times to determine KsA values for female runners across seven distance pairs from 100 m to 10,000 m. The data analyses are based on multiple official performance rankings at international to regional levels, exclusively compiled and processed for this study.

The KsA values obtained have remained stable for over four decades in national-level female runners and are applicable from world-class to regional levels. A sex-based analysis reveals that females undergo a more pronounced decrease in pace from 100 m to 1500 m in comparison to males. These sex differences in special endurance align with known variations in muscle fiber composition and fast-twitch type II fiber characteristics between males and females. In conclusion, we provide statistically valid KsA reference values for female runners from 100 m to 10,000 m. These values have practical implications for coaches and athletes seeking to assess runners’ strengths, weaknesses, potential, and specific talents based on race times. Sex differences in KsA values may reflect muscle physiology and guide future research on KsA and muscle function.

The online version contains supplementary material available at 10.1186/s13104-025-07256-6.