请教一下多少年龄段才是最好的训练� �间

[khris]

请教一下多少年龄段才是最好的训练� �间
18岁到21岁训练效果好么？
21岁以后训练效果好么？
25岁以后呢？

English please,

How many ages is the best training?
How many ages is the best training?
Is the training effect of 18 to 21 years good?
Does training work well after 21?
After 25 years?