The aim of this study is to establish a correlation between age and ranking among women's professional tennis players on WTA tour in order to formulate a reinforcement strategy for women's tennis in Japan.
Three types of analysis were carried out in this study. First, a comparison between male and female players was performed in terms of their respective ages when first ranked in the top 100. Second, a "transition of ranking" table was compiled for the women's WTA tour to dissect the process of ranking improvement. This indicated which ranking must be achieved at each age if a player is to reach her target ranking. Finally, the relationship between debut age and highest ranking in WTA was also explored.
The first analysis found that female players are about three years younger than their male counterparts when first ranked in the top 100. Furthermore, the table for "ranking transition" showed an absolute connection between age and systematic ranking improvement ; in particular, if a player is to reach top 30, she must make her debut on the WTA tour no later than junior high school. The result of the third analysis also demonstrated a strong correlation between debut age and highest ranking on WTA tour, giving ground to the lowering average age of women's tennis players. Despite having a strong representation on WTA tour, Japanese players could be prevented from further advancement in ranking by their relatively late debut, as their average debut age is among the oldest while best ranking is among the lowest. Hence, in order for women's professional tennis players in Japan to improve on their rankings, it is essential that they debut on WTA tour at the same time as domestic student competitions.