Towards a unified understanding of relative age effects.

When athletes are placed into annual age groups to organize and coordinate sport participation, certain (dis)advantages occur as a result of the subtle age differences within these groups. These differences, termed "relative age effects", have been consistently related to youth and adult sport attainment. However, there has been a lack of consistency in the terminology used in this area of research. In this paper, we consider the operational terms used in relative age research, discuss appropriate applications of terminology, and suggest directions for future research. Importantly, we argue for a unified understanding of what "relative age" means, stressing the need for clarity in directing future advances in the field.