Relative Age Effects among Physically Active Adolescents

Abstract: Background: Studies have shown that children and adolescents who are relatively older than their younger peers have advantages in sports, partly because they are more biologically mature, a relative age effect (RAE). However the occurrence of RAE in physical performance is still somewhat unclear and more knowledge is needed. Aim: The aim of this study was to investigate if there were any RAEs on anthropometric measures and physical performance in adolescents who are 13 years old and active in sports. Methods: 128 subjects (78 boys, 50 girls) from Malmö idrottsakademi, a school with a sports profile, were included in this study. Measurements of height and weight were taken and the physical performance was tested for grip strength, sprint and countermovement jump (CMJ). To analyse RAEs the subjects were divided into three groups (teriles) according to their month of birth. Subjects born in Tertile 1 (Jan-Apr) and Tertile 3 (Sep-Dec) were compared together as well as within and between the sexes with independent t-tests. Results: RAEs were present in height (p=0.01), weight (p=0.01), and grip strength (0.03) where higher values were found in the relatively older subjects. Additionally, if weight was accounted for, RAE was present in CMJ where the relatively younger subjects performed better (p=0.03). Further, when sexes was analysed separately the older boys were taller (p=0.01), heavier (p=0.02), and stronger (p=0.05) compared with the younger boys. The older girls were heavier (p=0.01) compared with the younger girls whereas the younger girls got a higher CMJ weight ratio (p=0.05). Conclusion: RAEs were found on anthropometric measures, but were less clear in physical performance. This indicates that although relatively older adolescents are taller and heavier, they are not always in advantage over their younger peers regarding physical performance.