Methods: The sample consisted of 8,564 individuals born in 1990 and 1995 (91% of the population) who engaged in sports within the ISI during the period of 1994-2009. The sample was divided into four groups; boys born in 1990 (n = 2271; 26.5%), girls born in 1990 (n = 2092; 24.4%), boys born in 1995 (n = 2175; 25.4%) and girls born in 1995 (n = 2026; 23.7%).
Úrtakið var 8.564 einstaklingar fæddir 1990 og 1995 (91% af þýði) sem stundað höfðu íþróttir innan ÍSÍ á árunum 1994-2009 og skiptist í fjóra hópa eftir kyni og fæðingarári; strákar fæddir 1990 (n = 2.271; 26,5%), stelpur fæddar 1990 (n = 2.092; 24,4%), strákar fæddir 1995 (n = 2.175; 25,4%) og stelpur fæddar 1995 (n = 2.026; 23,7%).