Analysis of characteristics and causes of relative age distribution of top youth athletes in China.

Objective:To analyse whether the advantage caused by "relative age" exsits in youth top athletes in China base on the foreign expert's research on relative age,and to discuss the possible causes of relative age advantage and the control measure.Methods:By applying method of data-collecting,we analyzed the distribution of birth dates collected from the athletes registering in 2007.Accord-ing to international athletic competition rules,these birth dates were divided into three age groups:junior B(age of 15 and 16),junior A(17 and 18) and youth groups(19 and 20).The data was analyzed by chi-square test.Result:With Chi-square test,significant differences were shown in relative age distribution in different age groups.The birth months of top track and field players in each group were shown significantly close to the beginning of competition(January),especially those of athletes born in the Q1 bearing a high proportion.In two years as the division of each standard age group in the same game,the "relative age" advantage became more significant in the players who were born in the previous year.Conclusion:The birth months of top track and field players in each group were shown significantly close to the beginning of competition,and the influence caused by relative age became weaken along with the growth of the age.