the ages concept is a look more then just the actual age of the athlete it takes into account more factors like the mental age of the athlete, everyone deals with stress differently or the the mental fortitude to deal with difficult training or their ability to understand the training they are doing, part of this could be the AGE OF EXPERIENCE the person has, someone new to sport will have a harder time compared to someone who has been training for years even if that person is older, of course some if you had to new people to sport it doesn't mean they will both face the same problems or do as well as each other, while they both may have a similar mental age they could be vastly different bodys, some kids develop younger then others starting
