Sex Differences in Youth Elite Swimming Performance

Abstract

Purpose: While it is well-known that elite males are faster than elite females in all Olympic-length swimming events, less is known about the age of the divergence in swimming performance between the sexes. Thus, this observational study compared swimming performance of elite male and female youths. Methods: We collected the all-time best 100 U.S. freestyle swimming performance times of boys and girls aged 5 to 18 years for six freestyle swimming events from 50m to 1500m. We compared data using univariate ANOVAs and Chi-squared tests. Results: Swimming performance improved with increasing age for both boys and girls (p<0.001) until a plateau— which began at a younger age for girls (15 years) than boys (17 years; sex × age; p<0.001). Before age 8, there was no sex difference in swimming performance (p>0.05). Beginning at age 9 however, boys swimming performance was faster than girls (1.0% to 1.3% depending on distance), and this sex difference in performance increased in magnitude until 18 years (p<0.001; 6.6% to 11.0% depending on distance). While boys represent 50% of the top 100 age-group performances at ages 5 and 6, boys represent an increasingly larger proportion of top performances across years of age including nearly 100% of all top 100 age-group performances beginning at age 15—except for one notable female swimmer in the 1500m Conclusion: Among elite youth swimmers, boys have increasingly faster performances than girls beginning at age 9 years, with minimal sex differences in swimming performance before 9 years. Additionally, boys represent an increasingly larger proportion of the top 100 age-group performances of all-time. No funding. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.