Background The timing and magnitude of sex differences in athletic performance during
early human development, prior to adulthood, is unknown. Objective To compare swimming
velocity of boys and girls for all Olympic-length freestyle swimming events to determine the
age of divergence in swimming performance. Methods We collected the all-time top 100 US
freestyle swimming performance times of boys and girls age 5 to 18 years for the 50m to
1500m events. Results Swimming performance improved with increasing age for boys and …

The timing and magnitude of sex differences in athletic performance during early human
development, prior to adulthood, is unknown. Objective To compare swimming velocity of
boys and girls for all Olympic‐length freestyle swimming events to determine the age of
divergence in swimming performance. Methods We collected the all‐time top 100 US
freestyle swimming performance times of boys and girls age 5 to 18 years for the 50m to
1500m events. Results Swimming performance improved with increasing age for boys and …