Performance in youth track and field is associated with birth quartile. A register-based study among athletes in Norway from 10 years to senior level.

Being born early in the year in events with high demand for specific physical capacities is an advantage in both sexes in most of the youngest competition classes. In males, the advantage of being born early in the year lasted longer in sprint than in middle-distance running, indicating that puberty affects performance in sprint and middle-distance running differently.